LCOV - code coverage report
Current view: top level - include/linux - xarray.h (source / functions) Hit Total Coverage
Test: gcov_data_raspi2_real_modules_combined.info Lines: 88 94 93.6 %
Date: 2020-09-30 20:25:40 Functions: 6 7 85.7 %
Branches: 170 284 59.9 %

           Branch data     Line data    Source code
       1                 :            : /* SPDX-License-Identifier: GPL-2.0+ */
       2                 :            : #ifndef _LINUX_XARRAY_H
       3                 :            : #define _LINUX_XARRAY_H
       4                 :            : /*
       5                 :            :  * eXtensible Arrays
       6                 :            :  * Copyright (c) 2017 Microsoft Corporation
       7                 :            :  * Author: Matthew Wilcox <willy@infradead.org>
       8                 :            :  *
       9                 :            :  * See Documentation/core-api/xarray.rst for how to use the XArray.
      10                 :            :  */
      11                 :            : 
      12                 :            : #include <linux/bug.h>
      13                 :            : #include <linux/compiler.h>
      14                 :            : #include <linux/gfp.h>
      15                 :            : #include <linux/kconfig.h>
      16                 :            : #include <linux/kernel.h>
      17                 :            : #include <linux/rcupdate.h>
      18                 :            : #include <linux/spinlock.h>
      19                 :            : #include <linux/types.h>
      20                 :            : 
      21                 :            : /*
      22                 :            :  * The bottom two bits of the entry determine how the XArray interprets
      23                 :            :  * the contents:
      24                 :            :  *
      25                 :            :  * 00: Pointer entry
      26                 :            :  * 10: Internal entry
      27                 :            :  * x1: Value entry or tagged pointer
      28                 :            :  *
      29                 :            :  * Attempting to store internal entries in the XArray is a bug.
      30                 :            :  *
      31                 :            :  * Most internal entries are pointers to the next node in the tree.
      32                 :            :  * The following internal entries have a special meaning:
      33                 :            :  *
      34                 :            :  * 0-62: Sibling entries
      35                 :            :  * 256: Zero entry
      36                 :            :  * 257: Retry entry
      37                 :            :  *
      38                 :            :  * Errors are also represented as internal entries, but use the negative
      39                 :            :  * space (-4094 to -2).  They're never stored in the slots array; only
      40                 :            :  * returned by the normal API.
      41                 :            :  */
      42                 :            : 
      43                 :            : #define BITS_PER_XA_VALUE       (BITS_PER_LONG - 1)
      44                 :            : 
      45                 :            : /**
      46                 :            :  * xa_mk_value() - Create an XArray entry from an integer.
      47                 :            :  * @v: Value to store in XArray.
      48                 :            :  *
      49                 :            :  * Context: Any context.
      50                 :            :  * Return: An entry suitable for storing in the XArray.
      51                 :            :  */
      52                 :      70204 : static inline void *xa_mk_value(unsigned long v)
      53                 :            : {
      54         [ -  + ]:      70204 :         WARN_ON((long)v < 0);
      55                 :      70204 :         return (void *)((v << 1) | 1);
      56                 :            : }
      57                 :            : 
      58                 :            : /**
      59                 :            :  * xa_to_value() - Get value stored in an XArray entry.
      60                 :            :  * @entry: XArray entry.
      61                 :            :  *
      62                 :            :  * Context: Any context.
      63                 :            :  * Return: The value stored in the XArray entry.
      64                 :            :  */
      65                 :            : static inline unsigned long xa_to_value(const void *entry)
      66                 :            : {
      67                 :      65857 :         return (unsigned long)entry >> 1;
      68                 :            : }
      69                 :            : 
      70                 :            : /**
      71                 :            :  * xa_is_value() - Determine if an entry is a value.
      72                 :            :  * @entry: XArray entry.
      73                 :            :  *
      74                 :            :  * Context: Any context.
      75                 :            :  * Return: True if the entry is a value, false if it is a pointer.
      76                 :            :  */
      77                 :            : static inline bool xa_is_value(const void *entry)
      78                 :            : {
      79                 :  296231698 :         return (unsigned long)entry & 1;
      80                 :            : }
      81                 :            : 
      82                 :            : /**
      83                 :            :  * xa_tag_pointer() - Create an XArray entry for a tagged pointer.
      84                 :            :  * @p: Plain pointer.
      85                 :            :  * @tag: Tag value (0, 1 or 3).
      86                 :            :  *
      87                 :            :  * If the user of the XArray prefers, they can tag their pointers instead
      88                 :            :  * of storing value entries.  Three tags are available (0, 1 and 3).
      89                 :            :  * These are distinct from the xa_mark_t as they are not replicated up
      90                 :            :  * through the array and cannot be searched for.
      91                 :            :  *
      92                 :            :  * Context: Any context.
      93                 :            :  * Return: An XArray entry.
      94                 :            :  */
      95                 :            : static inline void *xa_tag_pointer(void *p, unsigned long tag)
      96                 :            : {
      97                 :            :         return (void *)((unsigned long)p | tag);
      98                 :            : }
      99                 :            : 
     100                 :            : /**
     101                 :            :  * xa_untag_pointer() - Turn an XArray entry into a plain pointer.
     102                 :            :  * @entry: XArray entry.
     103                 :            :  *
     104                 :            :  * If you have stored a tagged pointer in the XArray, call this function
     105                 :            :  * to get the untagged version of the pointer.
     106                 :            :  *
     107                 :            :  * Context: Any context.
     108                 :            :  * Return: A pointer.
     109                 :            :  */
     110                 :            : static inline void *xa_untag_pointer(void *entry)
     111                 :            : {
     112                 :            :         return (void *)((unsigned long)entry & ~3UL);
     113                 :            : }
     114                 :            : 
     115                 :            : /**
     116                 :            :  * xa_pointer_tag() - Get the tag stored in an XArray entry.
     117                 :            :  * @entry: XArray entry.
     118                 :            :  *
     119                 :            :  * If you have stored a tagged pointer in the XArray, call this function
     120                 :            :  * to get the tag of that pointer.
     121                 :            :  *
     122                 :            :  * Context: Any context.
     123                 :            :  * Return: A tag.
     124                 :            :  */
     125                 :            : static inline unsigned int xa_pointer_tag(void *entry)
     126                 :            : {
     127                 :            :         return (unsigned long)entry & 3UL;
     128                 :            : }
     129                 :            : 
     130                 :            : /*
     131                 :            :  * xa_mk_internal() - Create an internal entry.
     132                 :            :  * @v: Value to turn into an internal entry.
     133                 :            :  *
     134                 :            :  * Internal entries are used for a number of purposes.  Entries 0-255 are
     135                 :            :  * used for sibling entries (only 0-62 are used by the current code).  256
     136                 :            :  * is used for the retry entry.  257 is used for the reserved / zero entry.
     137                 :            :  * Negative internal entries are used to represent errnos.  Node pointers
     138                 :            :  * are also tagged as internal entries in some situations.
     139                 :            :  *
     140                 :            :  * Context: Any context.
     141                 :            :  * Return: An XArray internal entry corresponding to this value.
     142                 :            :  */
     143                 :            : static inline void *xa_mk_internal(unsigned long v)
     144                 :            : {
     145                 :          0 :         return (void *)((v << 2) | 2);
     146                 :            : }
     147                 :            : 
     148                 :            : /*
     149                 :            :  * xa_to_internal() - Extract the value from an internal entry.
     150                 :            :  * @entry: XArray entry.
     151                 :            :  *
     152                 :            :  * Context: Any context.
     153                 :            :  * Return: The value which was stored in the internal entry.
     154                 :            :  */
     155                 :            : static inline unsigned long xa_to_internal(const void *entry)
     156                 :            : {
     157                 :            :         return (unsigned long)entry >> 2;
     158                 :            : }
     159                 :            : 
     160                 :            : /*
     161                 :            :  * xa_is_internal() - Is the entry an internal entry?
     162                 :            :  * @entry: XArray entry.
     163                 :            :  *
     164                 :            :  * Context: Any context.
     165                 :            :  * Return: %true if the entry is an internal entry.
     166                 :            :  */
     167                 :            : static inline bool xa_is_internal(const void *entry)
     168                 :            : {
     169                 :  798306748 :         return ((unsigned long)entry & 3) == 2;
     170                 :            : }
     171                 :            : 
     172                 :            : #define XA_ZERO_ENTRY           xa_mk_internal(257)
     173                 :            : 
     174                 :            : /**
     175                 :            :  * xa_is_zero() - Is the entry a zero entry?
     176                 :            :  * @entry: Entry retrieved from the XArray
     177                 :            :  *
     178                 :            :  * The normal API will return NULL as the contents of a slot containing
     179                 :            :  * a zero entry.  You can only see zero entries by using the advanced API.
     180                 :            :  *
     181                 :            :  * Return: %true if the entry is a zero entry.
     182                 :            :  */
     183                 :            : static inline bool xa_is_zero(const void *entry)
     184                 :            : {
     185                 :  241171164 :         return unlikely(entry == XA_ZERO_ENTRY);
     186                 :            : }
     187                 :            : 
     188                 :            : /**
     189                 :            :  * xa_is_err() - Report whether an XArray operation returned an error
     190                 :            :  * @entry: Result from calling an XArray function
     191                 :            :  *
     192                 :            :  * If an XArray operation cannot complete an operation, it will return
     193                 :            :  * a special value indicating an error.  This function tells you
     194                 :            :  * whether an error occurred; xa_err() tells you which error occurred.
     195                 :            :  *
     196                 :            :  * Context: Any context.
     197                 :            :  * Return: %true if the entry indicates an error.
     198                 :            :  */
     199                 :            : static inline bool xa_is_err(const void *entry)
     200                 :            : {
     201   [ +  +  +  +  :  244972718 :         return unlikely(xa_is_internal(entry) &&
          +  +  +  +  +  
          +  +  +  #  #  
          #  #  #  #  #  
          #  -  +  #  #  
          -  +  #  #  -  
          +  #  #  -  +  
          #  #  +  +  +  
             +  -  +  #  
                      # ]
     202                 :            :                         entry >= xa_mk_internal(-MAX_ERRNO));
     203                 :            : }
     204                 :            : 
     205                 :            : /**
     206                 :            :  * xa_err() - Turn an XArray result into an errno.
     207                 :            :  * @entry: Result from calling an XArray function.
     208                 :            :  *
     209                 :            :  * If an XArray operation cannot complete an operation, it will return
     210                 :            :  * a special pointer value which encodes an errno.  This function extracts
     211                 :            :  * the errno from the pointer value, or returns 0 if the pointer does not
     212                 :            :  * represent an errno.
     213                 :            :  *
     214                 :            :  * Context: Any context.
     215                 :            :  * Return: A negative errno or 0.
     216                 :            :  */
     217                 :            : static inline int xa_err(void *entry)
     218                 :            : {
     219                 :            :         /* xa_to_internal() would not do sign extension. */
     220   [ +  +  +  +  :  244972718 :         if (xa_is_err(entry))
          +  +  #  #  #  
          #  -  +  -  +  
          -  +  -  +  +  
                +  -  + ]
     221                 :     223530 :                 return (long)entry >> 2;
     222                 :            :         return 0;
     223                 :            : }
     224                 :            : 
     225                 :            : /**
     226                 :            :  * struct xa_limit - Represents a range of IDs.
     227                 :            :  * @min: The lowest ID to allocate (inclusive).
     228                 :            :  * @max: The maximum ID to allocate (inclusive).
     229                 :            :  *
     230                 :            :  * This structure is used either directly or via the XA_LIMIT() macro
     231                 :            :  * to communicate the range of IDs that are valid for allocation.
     232                 :            :  * Two common ranges are predefined for you:
     233                 :            :  * * xa_limit_32b       - [0 - UINT_MAX]
     234                 :            :  * * xa_limit_31b       - [0 - INT_MAX]
     235                 :            :  */
     236                 :            : struct xa_limit {
     237                 :            :         u32 max;
     238                 :            :         u32 min;
     239                 :            : };
     240                 :            : 
     241                 :            : #define XA_LIMIT(_min, _max) (struct xa_limit) { .min = _min, .max = _max }
     242                 :            : 
     243                 :            : #define xa_limit_32b    XA_LIMIT(0, UINT_MAX)
     244                 :            : #define xa_limit_31b    XA_LIMIT(0, INT_MAX)
     245                 :            : 
     246                 :            : typedef unsigned __bitwise xa_mark_t;
     247                 :            : #define XA_MARK_0               ((__force xa_mark_t)0U)
     248                 :            : #define XA_MARK_1               ((__force xa_mark_t)1U)
     249                 :            : #define XA_MARK_2               ((__force xa_mark_t)2U)
     250                 :            : #define XA_PRESENT              ((__force xa_mark_t)8U)
     251                 :            : #define XA_MARK_MAX             XA_MARK_2
     252                 :            : #define XA_FREE_MARK            XA_MARK_0
     253                 :            : 
     254                 :            : enum xa_lock_type {
     255                 :            :         XA_LOCK_IRQ = 1,
     256                 :            :         XA_LOCK_BH = 2,
     257                 :            : };
     258                 :            : 
     259                 :            : /*
     260                 :            :  * Values for xa_flags.  The radix tree stores its GFP flags in the xa_flags,
     261                 :            :  * and we remain compatible with that.
     262                 :            :  */
     263                 :            : #define XA_FLAGS_LOCK_IRQ       ((__force gfp_t)XA_LOCK_IRQ)
     264                 :            : #define XA_FLAGS_LOCK_BH        ((__force gfp_t)XA_LOCK_BH)
     265                 :            : #define XA_FLAGS_TRACK_FREE     ((__force gfp_t)4U)
     266                 :            : #define XA_FLAGS_ZERO_BUSY      ((__force gfp_t)8U)
     267                 :            : #define XA_FLAGS_ALLOC_WRAPPED  ((__force gfp_t)16U)
     268                 :            : #define XA_FLAGS_ACCOUNT        ((__force gfp_t)32U)
     269                 :            : #define XA_FLAGS_MARK(mark)     ((__force gfp_t)((1U << __GFP_BITS_SHIFT) << \
     270                 :            :                                                 (__force unsigned)(mark)))
     271                 :            : 
     272                 :            : /* ALLOC is for a normal 0-based alloc.  ALLOC1 is for an 1-based alloc */
     273                 :            : #define XA_FLAGS_ALLOC  (XA_FLAGS_TRACK_FREE | XA_FLAGS_MARK(XA_FREE_MARK))
     274                 :            : #define XA_FLAGS_ALLOC1 (XA_FLAGS_TRACK_FREE | XA_FLAGS_ZERO_BUSY)
     275                 :            : 
     276                 :            : /**
     277                 :            :  * struct xarray - The anchor of the XArray.
     278                 :            :  * @xa_lock: Lock that protects the contents of the XArray.
     279                 :            :  *
     280                 :            :  * To use the xarray, define it statically or embed it in your data structure.
     281                 :            :  * It is a very small data structure, so it does not usually make sense to
     282                 :            :  * allocate it separately and keep a pointer to it in your data structure.
     283                 :            :  *
     284                 :            :  * You may use the xa_lock to protect your own data structures as well.
     285                 :            :  */
     286                 :            : /*
     287                 :            :  * If all of the entries in the array are NULL, @xa_head is a NULL pointer.
     288                 :            :  * If the only non-NULL entry in the array is at index 0, @xa_head is that
     289                 :            :  * entry.  If any other entry in the array is non-NULL, @xa_head points
     290                 :            :  * to an @xa_node.
     291                 :            :  */
     292                 :            : struct xarray {
     293                 :            :         spinlock_t      xa_lock;
     294                 :            : /* private: The rest of the data structure is not to be used directly. */
     295                 :            :         gfp_t           xa_flags;
     296                 :            :         void __rcu *    xa_head;
     297                 :            : };
     298                 :            : 
     299                 :            : #define XARRAY_INIT(name, flags) {                              \
     300                 :            :         .xa_lock = __SPIN_LOCK_UNLOCKED(name.xa_lock),          \
     301                 :            :         .xa_flags = flags,                                      \
     302                 :            :         .xa_head = NULL,                                        \
     303                 :            : }
     304                 :            : 
     305                 :            : /**
     306                 :            :  * DEFINE_XARRAY_FLAGS() - Define an XArray with custom flags.
     307                 :            :  * @name: A string that names your XArray.
     308                 :            :  * @flags: XA_FLAG values.
     309                 :            :  *
     310                 :            :  * This is intended for file scope definitions of XArrays.  It declares
     311                 :            :  * and initialises an empty XArray with the chosen name and flags.  It is
     312                 :            :  * equivalent to calling xa_init_flags() on the array, but it does the
     313                 :            :  * initialisation at compiletime instead of runtime.
     314                 :            :  */
     315                 :            : #define DEFINE_XARRAY_FLAGS(name, flags)                                \
     316                 :            :         struct xarray name = XARRAY_INIT(name, flags)
     317                 :            : 
     318                 :            : /**
     319                 :            :  * DEFINE_XARRAY() - Define an XArray.
     320                 :            :  * @name: A string that names your XArray.
     321                 :            :  *
     322                 :            :  * This is intended for file scope definitions of XArrays.  It declares
     323                 :            :  * and initialises an empty XArray with the chosen name.  It is equivalent
     324                 :            :  * to calling xa_init() on the array, but it does the initialisation at
     325                 :            :  * compiletime instead of runtime.
     326                 :            :  */
     327                 :            : #define DEFINE_XARRAY(name) DEFINE_XARRAY_FLAGS(name, 0)
     328                 :            : 
     329                 :            : /**
     330                 :            :  * DEFINE_XARRAY_ALLOC() - Define an XArray which allocates IDs starting at 0.
     331                 :            :  * @name: A string that names your XArray.
     332                 :            :  *
     333                 :            :  * This is intended for file scope definitions of allocating XArrays.
     334                 :            :  * See also DEFINE_XARRAY().
     335                 :            :  */
     336                 :            : #define DEFINE_XARRAY_ALLOC(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC)
     337                 :            : 
     338                 :            : /**
     339                 :            :  * DEFINE_XARRAY_ALLOC1() - Define an XArray which allocates IDs starting at 1.
     340                 :            :  * @name: A string that names your XArray.
     341                 :            :  *
     342                 :            :  * This is intended for file scope definitions of allocating XArrays.
     343                 :            :  * See also DEFINE_XARRAY().
     344                 :            :  */
     345                 :            : #define DEFINE_XARRAY_ALLOC1(name) DEFINE_XARRAY_FLAGS(name, XA_FLAGS_ALLOC1)
     346                 :            : 
     347                 :            : void *xa_load(struct xarray *, unsigned long index);
     348                 :            : void *xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
     349                 :            : void *xa_erase(struct xarray *, unsigned long index);
     350                 :            : void *xa_store_range(struct xarray *, unsigned long first, unsigned long last,
     351                 :            :                         void *entry, gfp_t);
     352                 :            : bool xa_get_mark(struct xarray *, unsigned long index, xa_mark_t);
     353                 :            : void xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
     354                 :            : void xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
     355                 :            : void *xa_find(struct xarray *xa, unsigned long *index,
     356                 :            :                 unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
     357                 :            : void *xa_find_after(struct xarray *xa, unsigned long *index,
     358                 :            :                 unsigned long max, xa_mark_t) __attribute__((nonnull(2)));
     359                 :            : unsigned int xa_extract(struct xarray *, void **dst, unsigned long start,
     360                 :            :                 unsigned long max, unsigned int n, xa_mark_t);
     361                 :            : void xa_destroy(struct xarray *);
     362                 :            : 
     363                 :            : /**
     364                 :            :  * xa_init_flags() - Initialise an empty XArray with flags.
     365                 :            :  * @xa: XArray.
     366                 :            :  * @flags: XA_FLAG values.
     367                 :            :  *
     368                 :            :  * If you need to initialise an XArray with special flags (eg you need
     369                 :            :  * to take the lock from interrupt context), use this function instead
     370                 :            :  * of xa_init().
     371                 :            :  *
     372                 :            :  * Context: Any context.
     373                 :            :  */
     374                 :            : static inline void xa_init_flags(struct xarray *xa, gfp_t flags)
     375                 :            : {
     376                 :    4786056 :         spin_lock_init(&xa->xa_lock);
     377                 :    4786056 :         xa->xa_flags = flags;
     378                 :    4786056 :         xa->xa_head = NULL;
     379                 :            : }
     380                 :            : 
     381                 :            : /**
     382                 :            :  * xa_init() - Initialise an empty XArray.
     383                 :            :  * @xa: XArray.
     384                 :            :  *
     385                 :            :  * An empty XArray is full of NULL entries.
     386                 :            :  *
     387                 :            :  * Context: Any context.
     388                 :            :  */
     389                 :            : static inline void xa_init(struct xarray *xa)
     390                 :            : {
     391                 :            :         xa_init_flags(xa, 0);
     392                 :            : }
     393                 :            : 
     394                 :            : /**
     395                 :            :  * xa_empty() - Determine if an array has any present entries.
     396                 :            :  * @xa: XArray.
     397                 :            :  *
     398                 :            :  * Context: Any context.
     399                 :            :  * Return: %true if the array contains only NULL pointers.
     400                 :            :  */
     401                 :            : static inline bool xa_empty(const struct xarray *xa)
     402                 :            : {
     403                 :            :         return xa->xa_head == NULL;
     404                 :            : }
     405                 :            : 
     406                 :            : /**
     407                 :            :  * xa_marked() - Inquire whether any entry in this array has a mark set
     408                 :            :  * @xa: Array
     409                 :            :  * @mark: Mark value
     410                 :            :  *
     411                 :            :  * Context: Any context.
     412                 :            :  * Return: %true if any entry has this mark set.
     413                 :            :  */
     414                 :            : static inline bool xa_marked(const struct xarray *xa, xa_mark_t mark)
     415                 :            : {
     416         [ +  + ]:    8622532 :         return xa->xa_flags & XA_FLAGS_MARK(mark);
     417                 :            : }
     418                 :            : 
     419                 :            : /**
     420                 :            :  * xa_for_each_start() - Iterate over a portion of an XArray.
     421                 :            :  * @xa: XArray.
     422                 :            :  * @index: Index of @entry.
     423                 :            :  * @entry: Entry retrieved from array.
     424                 :            :  * @start: First index to retrieve from array.
     425                 :            :  *
     426                 :            :  * During the iteration, @entry will have the value of the entry stored
     427                 :            :  * in @xa at @index.  You may modify @index during the iteration if you
     428                 :            :  * want to skip or reprocess indices.  It is safe to modify the array
     429                 :            :  * during the iteration.  At the end of the iteration, @entry will be set
     430                 :            :  * to NULL and @index will have a value less than or equal to max.
     431                 :            :  *
     432                 :            :  * xa_for_each_start() is O(n.log(n)) while xas_for_each() is O(n).  You have
     433                 :            :  * to handle your own locking with xas_for_each(), and if you have to unlock
     434                 :            :  * after each iteration, it will also end up being O(n.log(n)).
     435                 :            :  * xa_for_each_start() will spin if it hits a retry entry; if you intend to
     436                 :            :  * see retry entries, you should use the xas_for_each() iterator instead.
     437                 :            :  * The xas_for_each() iterator will expand into more inline code than
     438                 :            :  * xa_for_each_start().
     439                 :            :  *
     440                 :            :  * Context: Any context.  Takes and releases the RCU lock.
     441                 :            :  */
     442                 :            : #define xa_for_each_start(xa, index, entry, start)                      \
     443                 :            :         for (index = start,                                             \
     444                 :            :              entry = xa_find(xa, &index, ULONG_MAX, XA_PRESENT);    \
     445                 :            :              entry;                                                     \
     446                 :            :              entry = xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT))
     447                 :            : 
     448                 :            : /**
     449                 :            :  * xa_for_each() - Iterate over present entries in an XArray.
     450                 :            :  * @xa: XArray.
     451                 :            :  * @index: Index of @entry.
     452                 :            :  * @entry: Entry retrieved from array.
     453                 :            :  *
     454                 :            :  * During the iteration, @entry will have the value of the entry stored
     455                 :            :  * in @xa at @index.  You may modify @index during the iteration if you want
     456                 :            :  * to skip or reprocess indices.  It is safe to modify the array during the
     457                 :            :  * iteration.  At the end of the iteration, @entry will be set to NULL and
     458                 :            :  * @index will have a value less than or equal to max.
     459                 :            :  *
     460                 :            :  * xa_for_each() is O(n.log(n)) while xas_for_each() is O(n).  You have
     461                 :            :  * to handle your own locking with xas_for_each(), and if you have to unlock
     462                 :            :  * after each iteration, it will also end up being O(n.log(n)).  xa_for_each()
     463                 :            :  * will spin if it hits a retry entry; if you intend to see retry entries,
     464                 :            :  * you should use the xas_for_each() iterator instead.  The xas_for_each()
     465                 :            :  * iterator will expand into more inline code than xa_for_each().
     466                 :            :  *
     467                 :            :  * Context: Any context.  Takes and releases the RCU lock.
     468                 :            :  */
     469                 :            : #define xa_for_each(xa, index, entry) \
     470                 :            :         xa_for_each_start(xa, index, entry, 0)
     471                 :            : 
     472                 :            : /**
     473                 :            :  * xa_for_each_marked() - Iterate over marked entries in an XArray.
     474                 :            :  * @xa: XArray.
     475                 :            :  * @index: Index of @entry.
     476                 :            :  * @entry: Entry retrieved from array.
     477                 :            :  * @filter: Selection criterion.
     478                 :            :  *
     479                 :            :  * During the iteration, @entry will have the value of the entry stored
     480                 :            :  * in @xa at @index.  The iteration will skip all entries in the array
     481                 :            :  * which do not match @filter.  You may modify @index during the iteration
     482                 :            :  * if you want to skip or reprocess indices.  It is safe to modify the array
     483                 :            :  * during the iteration.  At the end of the iteration, @entry will be set to
     484                 :            :  * NULL and @index will have a value less than or equal to max.
     485                 :            :  *
     486                 :            :  * xa_for_each_marked() is O(n.log(n)) while xas_for_each_marked() is O(n).
     487                 :            :  * You have to handle your own locking with xas_for_each(), and if you have
     488                 :            :  * to unlock after each iteration, it will also end up being O(n.log(n)).
     489                 :            :  * xa_for_each_marked() will spin if it hits a retry entry; if you intend to
     490                 :            :  * see retry entries, you should use the xas_for_each_marked() iterator
     491                 :            :  * instead.  The xas_for_each_marked() iterator will expand into more inline
     492                 :            :  * code than xa_for_each_marked().
     493                 :            :  *
     494                 :            :  * Context: Any context.  Takes and releases the RCU lock.
     495                 :            :  */
     496                 :            : #define xa_for_each_marked(xa, index, entry, filter) \
     497                 :            :         for (index = 0, entry = xa_find(xa, &index, ULONG_MAX, filter); \
     498                 :            :              entry; entry = xa_find_after(xa, &index, ULONG_MAX, filter))
     499                 :            : 
     500                 :            : #define xa_trylock(xa)          spin_trylock(&(xa)->xa_lock)
     501                 :            : #define xa_lock(xa)             spin_lock(&(xa)->xa_lock)
     502                 :            : #define xa_unlock(xa)           spin_unlock(&(xa)->xa_lock)
     503                 :            : #define xa_lock_bh(xa)          spin_lock_bh(&(xa)->xa_lock)
     504                 :            : #define xa_unlock_bh(xa)        spin_unlock_bh(&(xa)->xa_lock)
     505                 :            : #define xa_lock_irq(xa)         spin_lock_irq(&(xa)->xa_lock)
     506                 :            : #define xa_unlock_irq(xa)       spin_unlock_irq(&(xa)->xa_lock)
     507                 :            : #define xa_lock_irqsave(xa, flags) \
     508                 :            :                                 spin_lock_irqsave(&(xa)->xa_lock, flags)
     509                 :            : #define xa_unlock_irqrestore(xa, flags) \
     510                 :            :                                 spin_unlock_irqrestore(&(xa)->xa_lock, flags)
     511                 :            : 
     512                 :            : /*
     513                 :            :  * Versions of the normal API which require the caller to hold the
     514                 :            :  * xa_lock.  If the GFP flags allow it, they will drop the lock to
     515                 :            :  * allocate memory, then reacquire it afterwards.  These functions
     516                 :            :  * may also re-enable interrupts if the XArray flags indicate the
     517                 :            :  * locking should be interrupt safe.
     518                 :            :  */
     519                 :            : void *__xa_erase(struct xarray *, unsigned long index);
     520                 :            : void *__xa_store(struct xarray *, unsigned long index, void *entry, gfp_t);
     521                 :            : void *__xa_cmpxchg(struct xarray *, unsigned long index, void *old,
     522                 :            :                 void *entry, gfp_t);
     523                 :            : int __must_check __xa_insert(struct xarray *, unsigned long index,
     524                 :            :                 void *entry, gfp_t);
     525                 :            : int __must_check __xa_alloc(struct xarray *, u32 *id, void *entry,
     526                 :            :                 struct xa_limit, gfp_t);
     527                 :            : int __must_check __xa_alloc_cyclic(struct xarray *, u32 *id, void *entry,
     528                 :            :                 struct xa_limit, u32 *next, gfp_t);
     529                 :            : void __xa_set_mark(struct xarray *, unsigned long index, xa_mark_t);
     530                 :            : void __xa_clear_mark(struct xarray *, unsigned long index, xa_mark_t);
     531                 :            : 
     532                 :            : /**
     533                 :            :  * xa_store_bh() - Store this entry in the XArray.
     534                 :            :  * @xa: XArray.
     535                 :            :  * @index: Index into array.
     536                 :            :  * @entry: New entry.
     537                 :            :  * @gfp: Memory allocation flags.
     538                 :            :  *
     539                 :            :  * This function is like calling xa_store() except it disables softirqs
     540                 :            :  * while holding the array lock.
     541                 :            :  *
     542                 :            :  * Context: Any context.  Takes and releases the xa_lock while
     543                 :            :  * disabling softirqs.
     544                 :            :  * Return: The entry which used to be at this index.
     545                 :            :  */
     546                 :            : static inline void *xa_store_bh(struct xarray *xa, unsigned long index,
     547                 :            :                 void *entry, gfp_t gfp)
     548                 :            : {
     549                 :            :         void *curr;
     550                 :            : 
     551                 :            :         xa_lock_bh(xa);
     552                 :            :         curr = __xa_store(xa, index, entry, gfp);
     553                 :            :         xa_unlock_bh(xa);
     554                 :            : 
     555                 :            :         return curr;
     556                 :            : }
     557                 :            : 
     558                 :            : /**
     559                 :            :  * xa_store_irq() - Store this entry in the XArray.
     560                 :            :  * @xa: XArray.
     561                 :            :  * @index: Index into array.
     562                 :            :  * @entry: New entry.
     563                 :            :  * @gfp: Memory allocation flags.
     564                 :            :  *
     565                 :            :  * This function is like calling xa_store() except it disables interrupts
     566                 :            :  * while holding the array lock.
     567                 :            :  *
     568                 :            :  * Context: Process context.  Takes and releases the xa_lock while
     569                 :            :  * disabling interrupts.
     570                 :            :  * Return: The entry which used to be at this index.
     571                 :            :  */
     572                 :            : static inline void *xa_store_irq(struct xarray *xa, unsigned long index,
     573                 :            :                 void *entry, gfp_t gfp)
     574                 :            : {
     575                 :            :         void *curr;
     576                 :            : 
     577                 :            :         xa_lock_irq(xa);
     578                 :            :         curr = __xa_store(xa, index, entry, gfp);
     579                 :            :         xa_unlock_irq(xa);
     580                 :            : 
     581                 :            :         return curr;
     582                 :            : }
     583                 :            : 
     584                 :            : /**
     585                 :            :  * xa_erase_bh() - Erase this entry from the XArray.
     586                 :            :  * @xa: XArray.
     587                 :            :  * @index: Index of entry.
     588                 :            :  *
     589                 :            :  * After this function returns, loading from @index will return %NULL.
     590                 :            :  * If the index is part of a multi-index entry, all indices will be erased
     591                 :            :  * and none of the entries will be part of a multi-index entry.
     592                 :            :  *
     593                 :            :  * Context: Any context.  Takes and releases the xa_lock while
     594                 :            :  * disabling softirqs.
     595                 :            :  * Return: The entry which used to be at this index.
     596                 :            :  */
     597                 :            : static inline void *xa_erase_bh(struct xarray *xa, unsigned long index)
     598                 :            : {
     599                 :            :         void *entry;
     600                 :            : 
     601                 :            :         xa_lock_bh(xa);
     602                 :            :         entry = __xa_erase(xa, index);
     603                 :            :         xa_unlock_bh(xa);
     604                 :            : 
     605                 :            :         return entry;
     606                 :            : }
     607                 :            : 
     608                 :            : /**
     609                 :            :  * xa_erase_irq() - Erase this entry from the XArray.
     610                 :            :  * @xa: XArray.
     611                 :            :  * @index: Index of entry.
     612                 :            :  *
     613                 :            :  * After this function returns, loading from @index will return %NULL.
     614                 :            :  * If the index is part of a multi-index entry, all indices will be erased
     615                 :            :  * and none of the entries will be part of a multi-index entry.
     616                 :            :  *
     617                 :            :  * Context: Process context.  Takes and releases the xa_lock while
     618                 :            :  * disabling interrupts.
     619                 :            :  * Return: The entry which used to be at this index.
     620                 :            :  */
     621                 :            : static inline void *xa_erase_irq(struct xarray *xa, unsigned long index)
     622                 :            : {
     623                 :            :         void *entry;
     624                 :            : 
     625                 :            :         xa_lock_irq(xa);
     626                 :            :         entry = __xa_erase(xa, index);
     627                 :            :         xa_unlock_irq(xa);
     628                 :            : 
     629                 :            :         return entry;
     630                 :            : }
     631                 :            : 
     632                 :            : /**
     633                 :            :  * xa_cmpxchg() - Conditionally replace an entry in the XArray.
     634                 :            :  * @xa: XArray.
     635                 :            :  * @index: Index into array.
     636                 :            :  * @old: Old value to test against.
     637                 :            :  * @entry: New value to place in array.
     638                 :            :  * @gfp: Memory allocation flags.
     639                 :            :  *
     640                 :            :  * If the entry at @index is the same as @old, replace it with @entry.
     641                 :            :  * If the return value is equal to @old, then the exchange was successful.
     642                 :            :  *
     643                 :            :  * Context: Any context.  Takes and releases the xa_lock.  May sleep
     644                 :            :  * if the @gfp flags permit.
     645                 :            :  * Return: The old value at this index or xa_err() if an error happened.
     646                 :            :  */
     647                 :            : static inline void *xa_cmpxchg(struct xarray *xa, unsigned long index,
     648                 :            :                         void *old, void *entry, gfp_t gfp)
     649                 :            : {
     650                 :            :         void *curr;
     651                 :            : 
     652                 :            :         xa_lock(xa);
     653                 :            :         curr = __xa_cmpxchg(xa, index, old, entry, gfp);
     654                 :            :         xa_unlock(xa);
     655                 :            : 
     656                 :            :         return curr;
     657                 :            : }
     658                 :            : 
     659                 :            : /**
     660                 :            :  * xa_cmpxchg_bh() - Conditionally replace an entry in the XArray.
     661                 :            :  * @xa: XArray.
     662                 :            :  * @index: Index into array.
     663                 :            :  * @old: Old value to test against.
     664                 :            :  * @entry: New value to place in array.
     665                 :            :  * @gfp: Memory allocation flags.
     666                 :            :  *
     667                 :            :  * This function is like calling xa_cmpxchg() except it disables softirqs
     668                 :            :  * while holding the array lock.
     669                 :            :  *
     670                 :            :  * Context: Any context.  Takes and releases the xa_lock while
     671                 :            :  * disabling softirqs.  May sleep if the @gfp flags permit.
     672                 :            :  * Return: The old value at this index or xa_err() if an error happened.
     673                 :            :  */
     674                 :            : static inline void *xa_cmpxchg_bh(struct xarray *xa, unsigned long index,
     675                 :            :                         void *old, void *entry, gfp_t gfp)
     676                 :            : {
     677                 :            :         void *curr;
     678                 :            : 
     679                 :            :         xa_lock_bh(xa);
     680                 :            :         curr = __xa_cmpxchg(xa, index, old, entry, gfp);
     681                 :            :         xa_unlock_bh(xa);
     682                 :            : 
     683                 :            :         return curr;
     684                 :            : }
     685                 :            : 
     686                 :            : /**
     687                 :            :  * xa_cmpxchg_irq() - Conditionally replace an entry in the XArray.
     688                 :            :  * @xa: XArray.
     689                 :            :  * @index: Index into array.
     690                 :            :  * @old: Old value to test against.
     691                 :            :  * @entry: New value to place in array.
     692                 :            :  * @gfp: Memory allocation flags.
     693                 :            :  *
     694                 :            :  * This function is like calling xa_cmpxchg() except it disables interrupts
     695                 :            :  * while holding the array lock.
     696                 :            :  *
     697                 :            :  * Context: Process context.  Takes and releases the xa_lock while
     698                 :            :  * disabling interrupts.  May sleep if the @gfp flags permit.
     699                 :            :  * Return: The old value at this index or xa_err() if an error happened.
     700                 :            :  */
     701                 :          0 : static inline void *xa_cmpxchg_irq(struct xarray *xa, unsigned long index,
     702                 :            :                         void *old, void *entry, gfp_t gfp)
     703                 :            : {
     704                 :            :         void *curr;
     705                 :            : 
     706                 :            :         xa_lock_irq(xa);
     707                 :          0 :         curr = __xa_cmpxchg(xa, index, old, entry, gfp);
     708                 :            :         xa_unlock_irq(xa);
     709                 :            : 
     710                 :          0 :         return curr;
     711                 :            : }
     712                 :            : 
     713                 :            : /**
     714                 :            :  * xa_insert() - Store this entry in the XArray unless another entry is
     715                 :            :  *                      already present.
     716                 :            :  * @xa: XArray.
     717                 :            :  * @index: Index into array.
     718                 :            :  * @entry: New entry.
     719                 :            :  * @gfp: Memory allocation flags.
     720                 :            :  *
     721                 :            :  * Inserting a NULL entry will store a reserved entry (like xa_reserve())
     722                 :            :  * if no entry is present.  Inserting will fail if a reserved entry is
     723                 :            :  * present, even though loading from this index will return NULL.
     724                 :            :  *
     725                 :            :  * Context: Any context.  Takes and releases the xa_lock.  May sleep if
     726                 :            :  * the @gfp flags permit.
     727                 :            :  * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
     728                 :            :  * -ENOMEM if memory could not be allocated.
     729                 :            :  */
     730                 :            : static inline int __must_check xa_insert(struct xarray *xa,
     731                 :            :                 unsigned long index, void *entry, gfp_t gfp)
     732                 :            : {
     733                 :            :         int err;
     734                 :            : 
     735                 :            :         xa_lock(xa);
     736                 :            :         err = __xa_insert(xa, index, entry, gfp);
     737                 :            :         xa_unlock(xa);
     738                 :            : 
     739                 :            :         return err;
     740                 :            : }
     741                 :            : 
     742                 :            : /**
     743                 :            :  * xa_insert_bh() - Store this entry in the XArray unless another entry is
     744                 :            :  *                      already present.
     745                 :            :  * @xa: XArray.
     746                 :            :  * @index: Index into array.
     747                 :            :  * @entry: New entry.
     748                 :            :  * @gfp: Memory allocation flags.
     749                 :            :  *
     750                 :            :  * Inserting a NULL entry will store a reserved entry (like xa_reserve())
     751                 :            :  * if no entry is present.  Inserting will fail if a reserved entry is
     752                 :            :  * present, even though loading from this index will return NULL.
     753                 :            :  *
     754                 :            :  * Context: Any context.  Takes and releases the xa_lock while
     755                 :            :  * disabling softirqs.  May sleep if the @gfp flags permit.
     756                 :            :  * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
     757                 :            :  * -ENOMEM if memory could not be allocated.
     758                 :            :  */
     759                 :            : static inline int __must_check xa_insert_bh(struct xarray *xa,
     760                 :            :                 unsigned long index, void *entry, gfp_t gfp)
     761                 :            : {
     762                 :            :         int err;
     763                 :            : 
     764                 :            :         xa_lock_bh(xa);
     765                 :            :         err = __xa_insert(xa, index, entry, gfp);
     766                 :            :         xa_unlock_bh(xa);
     767                 :            : 
     768                 :            :         return err;
     769                 :            : }
     770                 :            : 
     771                 :            : /**
     772                 :            :  * xa_insert_irq() - Store this entry in the XArray unless another entry is
     773                 :            :  *                      already present.
     774                 :            :  * @xa: XArray.
     775                 :            :  * @index: Index into array.
     776                 :            :  * @entry: New entry.
     777                 :            :  * @gfp: Memory allocation flags.
     778                 :            :  *
     779                 :            :  * Inserting a NULL entry will store a reserved entry (like xa_reserve())
     780                 :            :  * if no entry is present.  Inserting will fail if a reserved entry is
     781                 :            :  * present, even though loading from this index will return NULL.
     782                 :            :  *
     783                 :            :  * Context: Process context.  Takes and releases the xa_lock while
     784                 :            :  * disabling interrupts.  May sleep if the @gfp flags permit.
     785                 :            :  * Return: 0 if the store succeeded.  -EBUSY if another entry was present.
     786                 :            :  * -ENOMEM if memory could not be allocated.
     787                 :            :  */
     788                 :            : static inline int __must_check xa_insert_irq(struct xarray *xa,
     789                 :            :                 unsigned long index, void *entry, gfp_t gfp)
     790                 :            : {
     791                 :            :         int err;
     792                 :            : 
     793                 :            :         xa_lock_irq(xa);
     794                 :            :         err = __xa_insert(xa, index, entry, gfp);
     795                 :            :         xa_unlock_irq(xa);
     796                 :            : 
     797                 :            :         return err;
     798                 :            : }
     799                 :            : 
     800                 :            : /**
     801                 :            :  * xa_alloc() - Find somewhere to store this entry in the XArray.
     802                 :            :  * @xa: XArray.
     803                 :            :  * @id: Pointer to ID.
     804                 :            :  * @entry: New entry.
     805                 :            :  * @limit: Range of ID to allocate.
     806                 :            :  * @gfp: Memory allocation flags.
     807                 :            :  *
     808                 :            :  * Finds an empty entry in @xa between @limit.min and @limit.max,
     809                 :            :  * stores the index into the @id pointer, then stores the entry at
     810                 :            :  * that index.  A concurrent lookup will not see an uninitialised @id.
     811                 :            :  *
     812                 :            :  * Context: Any context.  Takes and releases the xa_lock.  May sleep if
     813                 :            :  * the @gfp flags permit.
     814                 :            :  * Return: 0 on success, -ENOMEM if memory could not be allocated or
     815                 :            :  * -EBUSY if there are no free entries in @limit.
     816                 :            :  */
     817                 :        414 : static inline __must_check int xa_alloc(struct xarray *xa, u32 *id,
     818                 :            :                 void *entry, struct xa_limit limit, gfp_t gfp)
     819                 :            : {
     820                 :            :         int err;
     821                 :            : 
     822                 :            :         xa_lock(xa);
     823                 :        414 :         err = __xa_alloc(xa, id, entry, limit, gfp);
     824                 :            :         xa_unlock(xa);
     825                 :            : 
     826                 :        414 :         return err;
     827                 :            : }
     828                 :            : 
     829                 :            : /**
     830                 :            :  * xa_alloc_bh() - Find somewhere to store this entry in the XArray.
     831                 :            :  * @xa: XArray.
     832                 :            :  * @id: Pointer to ID.
     833                 :            :  * @entry: New entry.
     834                 :            :  * @limit: Range of ID to allocate.
     835                 :            :  * @gfp: Memory allocation flags.
     836                 :            :  *
     837                 :            :  * Finds an empty entry in @xa between @limit.min and @limit.max,
     838                 :            :  * stores the index into the @id pointer, then stores the entry at
     839                 :            :  * that index.  A concurrent lookup will not see an uninitialised @id.
     840                 :            :  *
     841                 :            :  * Context: Any context.  Takes and releases the xa_lock while
     842                 :            :  * disabling softirqs.  May sleep if the @gfp flags permit.
     843                 :            :  * Return: 0 on success, -ENOMEM if memory could not be allocated or
     844                 :            :  * -EBUSY if there are no free entries in @limit.
     845                 :            :  */
     846                 :            : static inline int __must_check xa_alloc_bh(struct xarray *xa, u32 *id,
     847                 :            :                 void *entry, struct xa_limit limit, gfp_t gfp)
     848                 :            : {
     849                 :            :         int err;
     850                 :            : 
     851                 :            :         xa_lock_bh(xa);
     852                 :            :         err = __xa_alloc(xa, id, entry, limit, gfp);
     853                 :            :         xa_unlock_bh(xa);
     854                 :            : 
     855                 :            :         return err;
     856                 :            : }
     857                 :            : 
     858                 :            : /**
     859                 :            :  * xa_alloc_irq() - Find somewhere to store this entry in the XArray.
     860                 :            :  * @xa: XArray.
     861                 :            :  * @id: Pointer to ID.
     862                 :            :  * @entry: New entry.
     863                 :            :  * @limit: Range of ID to allocate.
     864                 :            :  * @gfp: Memory allocation flags.
     865                 :            :  *
     866                 :            :  * Finds an empty entry in @xa between @limit.min and @limit.max,
     867                 :            :  * stores the index into the @id pointer, then stores the entry at
     868                 :            :  * that index.  A concurrent lookup will not see an uninitialised @id.
     869                 :            :  *
     870                 :            :  * Context: Process context.  Takes and releases the xa_lock while
     871                 :            :  * disabling interrupts.  May sleep if the @gfp flags permit.
     872                 :            :  * Return: 0 on success, -ENOMEM if memory could not be allocated or
     873                 :            :  * -EBUSY if there are no free entries in @limit.
     874                 :            :  */
     875                 :            : static inline int __must_check xa_alloc_irq(struct xarray *xa, u32 *id,
     876                 :            :                 void *entry, struct xa_limit limit, gfp_t gfp)
     877                 :            : {
     878                 :            :         int err;
     879                 :            : 
     880                 :            :         xa_lock_irq(xa);
     881                 :            :         err = __xa_alloc(xa, id, entry, limit, gfp);
     882                 :            :         xa_unlock_irq(xa);
     883                 :            : 
     884                 :            :         return err;
     885                 :            : }
     886                 :            : 
     887                 :            : /**
     888                 :            :  * xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
     889                 :            :  * @xa: XArray.
     890                 :            :  * @id: Pointer to ID.
     891                 :            :  * @entry: New entry.
     892                 :            :  * @limit: Range of allocated ID.
     893                 :            :  * @next: Pointer to next ID to allocate.
     894                 :            :  * @gfp: Memory allocation flags.
     895                 :            :  *
     896                 :            :  * Finds an empty entry in @xa between @limit.min and @limit.max,
     897                 :            :  * stores the index into the @id pointer, then stores the entry at
     898                 :            :  * that index.  A concurrent lookup will not see an uninitialised @id.
     899                 :            :  * The search for an empty entry will start at @next and will wrap
     900                 :            :  * around if necessary.
     901                 :            :  *
     902                 :            :  * Context: Any context.  Takes and releases the xa_lock.  May sleep if
     903                 :            :  * the @gfp flags permit.
     904                 :            :  * Return: 0 if the allocation succeeded without wrapping.  1 if the
     905                 :            :  * allocation succeeded after wrapping, -ENOMEM if memory could not be
     906                 :            :  * allocated or -EBUSY if there are no free entries in @limit.
     907                 :            :  */
     908                 :            : static inline int xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
     909                 :            :                 struct xa_limit limit, u32 *next, gfp_t gfp)
     910                 :            : {
     911                 :            :         int err;
     912                 :            : 
     913                 :            :         xa_lock(xa);
     914                 :            :         err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
     915                 :            :         xa_unlock(xa);
     916                 :            : 
     917                 :            :         return err;
     918                 :            : }
     919                 :            : 
     920                 :            : /**
     921                 :            :  * xa_alloc_cyclic_bh() - Find somewhere to store this entry in the XArray.
     922                 :            :  * @xa: XArray.
     923                 :            :  * @id: Pointer to ID.
     924                 :            :  * @entry: New entry.
     925                 :            :  * @limit: Range of allocated ID.
     926                 :            :  * @next: Pointer to next ID to allocate.
     927                 :            :  * @gfp: Memory allocation flags.
     928                 :            :  *
     929                 :            :  * Finds an empty entry in @xa between @limit.min and @limit.max,
     930                 :            :  * stores the index into the @id pointer, then stores the entry at
     931                 :            :  * that index.  A concurrent lookup will not see an uninitialised @id.
     932                 :            :  * The search for an empty entry will start at @next and will wrap
     933                 :            :  * around if necessary.
     934                 :            :  *
     935                 :            :  * Context: Any context.  Takes and releases the xa_lock while
     936                 :            :  * disabling softirqs.  May sleep if the @gfp flags permit.
     937                 :            :  * Return: 0 if the allocation succeeded without wrapping.  1 if the
     938                 :            :  * allocation succeeded after wrapping, -ENOMEM if memory could not be
     939                 :            :  * allocated or -EBUSY if there are no free entries in @limit.
     940                 :            :  */
     941                 :            : static inline int xa_alloc_cyclic_bh(struct xarray *xa, u32 *id, void *entry,
     942                 :            :                 struct xa_limit limit, u32 *next, gfp_t gfp)
     943                 :            : {
     944                 :            :         int err;
     945                 :            : 
     946                 :            :         xa_lock_bh(xa);
     947                 :            :         err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
     948                 :            :         xa_unlock_bh(xa);
     949                 :            : 
     950                 :            :         return err;
     951                 :            : }
     952                 :            : 
     953                 :            : /**
     954                 :            :  * xa_alloc_cyclic_irq() - Find somewhere to store this entry in the XArray.
     955                 :            :  * @xa: XArray.
     956                 :            :  * @id: Pointer to ID.
     957                 :            :  * @entry: New entry.
     958                 :            :  * @limit: Range of allocated ID.
     959                 :            :  * @next: Pointer to next ID to allocate.
     960                 :            :  * @gfp: Memory allocation flags.
     961                 :            :  *
     962                 :            :  * Finds an empty entry in @xa between @limit.min and @limit.max,
     963                 :            :  * stores the index into the @id pointer, then stores the entry at
     964                 :            :  * that index.  A concurrent lookup will not see an uninitialised @id.
     965                 :            :  * The search for an empty entry will start at @next and will wrap
     966                 :            :  * around if necessary.
     967                 :            :  *
     968                 :            :  * Context: Process context.  Takes and releases the xa_lock while
     969                 :            :  * disabling interrupts.  May sleep if the @gfp flags permit.
     970                 :            :  * Return: 0 if the allocation succeeded without wrapping.  1 if the
     971                 :            :  * allocation succeeded after wrapping, -ENOMEM if memory could not be
     972                 :            :  * allocated or -EBUSY if there are no free entries in @limit.
     973                 :            :  */
     974                 :            : static inline int xa_alloc_cyclic_irq(struct xarray *xa, u32 *id, void *entry,
     975                 :            :                 struct xa_limit limit, u32 *next, gfp_t gfp)
     976                 :            : {
     977                 :            :         int err;
     978                 :            : 
     979                 :            :         xa_lock_irq(xa);
     980                 :            :         err = __xa_alloc_cyclic(xa, id, entry, limit, next, gfp);
     981                 :            :         xa_unlock_irq(xa);
     982                 :            : 
     983                 :            :         return err;
     984                 :            : }
     985                 :            : 
     986                 :            : /**
     987                 :            :  * xa_reserve() - Reserve this index in the XArray.
     988                 :            :  * @xa: XArray.
     989                 :            :  * @index: Index into array.
     990                 :            :  * @gfp: Memory allocation flags.
     991                 :            :  *
     992                 :            :  * Ensures there is somewhere to store an entry at @index in the array.
     993                 :            :  * If there is already something stored at @index, this function does
     994                 :            :  * nothing.  If there was nothing there, the entry is marked as reserved.
     995                 :            :  * Loading from a reserved entry returns a %NULL pointer.
     996                 :            :  *
     997                 :            :  * If you do not use the entry that you have reserved, call xa_release()
     998                 :            :  * or xa_erase() to free any unnecessary memory.
     999                 :            :  *
    1000                 :            :  * Context: Any context.  Takes and releases the xa_lock.
    1001                 :            :  * May sleep if the @gfp flags permit.
    1002                 :            :  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
    1003                 :            :  */
    1004                 :            : static inline __must_check
    1005                 :            : int xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
    1006                 :            : {
    1007                 :            :         return xa_err(xa_cmpxchg(xa, index, NULL, XA_ZERO_ENTRY, gfp));
    1008                 :            : }
    1009                 :            : 
    1010                 :            : /**
    1011                 :            :  * xa_reserve_bh() - Reserve this index in the XArray.
    1012                 :            :  * @xa: XArray.
    1013                 :            :  * @index: Index into array.
    1014                 :            :  * @gfp: Memory allocation flags.
    1015                 :            :  *
    1016                 :            :  * A softirq-disabling version of xa_reserve().
    1017                 :            :  *
    1018                 :            :  * Context: Any context.  Takes and releases the xa_lock while
    1019                 :            :  * disabling softirqs.
    1020                 :            :  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
    1021                 :            :  */
    1022                 :            : static inline __must_check
    1023                 :            : int xa_reserve_bh(struct xarray *xa, unsigned long index, gfp_t gfp)
    1024                 :            : {
    1025                 :            :         return xa_err(xa_cmpxchg_bh(xa, index, NULL, XA_ZERO_ENTRY, gfp));
    1026                 :            : }
    1027                 :            : 
    1028                 :            : /**
    1029                 :            :  * xa_reserve_irq() - Reserve this index in the XArray.
    1030                 :            :  * @xa: XArray.
    1031                 :            :  * @index: Index into array.
    1032                 :            :  * @gfp: Memory allocation flags.
    1033                 :            :  *
    1034                 :            :  * An interrupt-disabling version of xa_reserve().
    1035                 :            :  *
    1036                 :            :  * Context: Process context.  Takes and releases the xa_lock while
    1037                 :            :  * disabling interrupts.
    1038                 :            :  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
    1039                 :            :  */
    1040                 :            : static inline __must_check
    1041                 :            : int xa_reserve_irq(struct xarray *xa, unsigned long index, gfp_t gfp)
    1042                 :            : {
    1043                 :            :         return xa_err(xa_cmpxchg_irq(xa, index, NULL, XA_ZERO_ENTRY, gfp));
    1044                 :            : }
    1045                 :            : 
    1046                 :            : /**
    1047                 :            :  * xa_release() - Release a reserved entry.
    1048                 :            :  * @xa: XArray.
    1049                 :            :  * @index: Index of entry.
    1050                 :            :  *
    1051                 :            :  * After calling xa_reserve(), you can call this function to release the
    1052                 :            :  * reservation.  If the entry at @index has been stored to, this function
    1053                 :            :  * will do nothing.
    1054                 :            :  */
    1055                 :            : static inline void xa_release(struct xarray *xa, unsigned long index)
    1056                 :            : {
    1057                 :            :         xa_cmpxchg(xa, index, XA_ZERO_ENTRY, NULL, 0);
    1058                 :            : }
    1059                 :            : 
    1060                 :            : /* Everything below here is the Advanced API.  Proceed with caution. */
    1061                 :            : 
    1062                 :            : /*
    1063                 :            :  * The xarray is constructed out of a set of 'chunks' of pointers.  Choosing
    1064                 :            :  * the best chunk size requires some tradeoffs.  A power of two recommends
    1065                 :            :  * itself so that we can walk the tree based purely on shifts and masks.
    1066                 :            :  * Generally, the larger the better; as the number of slots per level of the
    1067                 :            :  * tree increases, the less tall the tree needs to be.  But that needs to be
    1068                 :            :  * balanced against the memory consumption of each node.  On a 64-bit system,
    1069                 :            :  * xa_node is currently 576 bytes, and we get 7 of them per 4kB page.  If we
    1070                 :            :  * doubled the number of slots per node, we'd get only 3 nodes per 4kB page.
    1071                 :            :  */
    1072                 :            : #ifndef XA_CHUNK_SHIFT
    1073                 :            : #define XA_CHUNK_SHIFT          (CONFIG_BASE_SMALL ? 4 : 6)
    1074                 :            : #endif
    1075                 :            : #define XA_CHUNK_SIZE           (1UL << XA_CHUNK_SHIFT)
    1076                 :            : #define XA_CHUNK_MASK           (XA_CHUNK_SIZE - 1)
    1077                 :            : #define XA_MAX_MARKS            3
    1078                 :            : #define XA_MARK_LONGS           DIV_ROUND_UP(XA_CHUNK_SIZE, BITS_PER_LONG)
    1079                 :            : 
    1080                 :            : /*
    1081                 :            :  * @count is the count of every non-NULL element in the ->slots array
    1082                 :            :  * whether that is a value entry, a retry entry, a user pointer,
    1083                 :            :  * a sibling entry or a pointer to the next level of the tree.
    1084                 :            :  * @nr_values is the count of every element in ->slots which is
    1085                 :            :  * either a value entry or a sibling of a value entry.
    1086                 :            :  */
    1087                 :            : struct xa_node {
    1088                 :            :         unsigned char   shift;          /* Bits remaining in each slot */
    1089                 :            :         unsigned char   offset;         /* Slot offset in parent */
    1090                 :            :         unsigned char   count;          /* Total entry count */
    1091                 :            :         unsigned char   nr_values;      /* Value entry count */
    1092                 :            :         struct xa_node __rcu *parent;   /* NULL at top of tree */
    1093                 :            :         struct xarray   *array;         /* The array we belong to */
    1094                 :            :         union {
    1095                 :            :                 struct list_head private_list;  /* For tree user */
    1096                 :            :                 struct rcu_head rcu_head;       /* Used when freeing node */
    1097                 :            :         };
    1098                 :            :         void __rcu      *slots[XA_CHUNK_SIZE];
    1099                 :            :         union {
    1100                 :            :                 unsigned long   tags[XA_MAX_MARKS][XA_MARK_LONGS];
    1101                 :            :                 unsigned long   marks[XA_MAX_MARKS][XA_MARK_LONGS];
    1102                 :            :         };
    1103                 :            : };
    1104                 :            : 
    1105                 :            : void xa_dump(const struct xarray *);
    1106                 :            : void xa_dump_node(const struct xa_node *);
    1107                 :            : 
    1108                 :            : #ifdef XA_DEBUG
    1109                 :            : #define XA_BUG_ON(xa, x) do {                                   \
    1110                 :            :                 if (x) {                                        \
    1111                 :            :                         xa_dump(xa);                            \
    1112                 :            :                         BUG();                                  \
    1113                 :            :                 }                                               \
    1114                 :            :         } while (0)
    1115                 :            : #define XA_NODE_BUG_ON(node, x) do {                            \
    1116                 :            :                 if (x) {                                        \
    1117                 :            :                         if (node) xa_dump_node(node);           \
    1118                 :            :                         BUG();                                  \
    1119                 :            :                 }                                               \
    1120                 :            :         } while (0)
    1121                 :            : #else
    1122                 :            : #define XA_BUG_ON(xa, x)        do { } while (0)
    1123                 :            : #define XA_NODE_BUG_ON(node, x) do { } while (0)
    1124                 :            : #endif
    1125                 :            : 
    1126                 :            : /* Private */
    1127                 :            : static inline void *xa_head(const struct xarray *xa)
    1128                 :            : {
    1129                 :  128402701 :         return rcu_dereference_check(xa->xa_head,
    1130                 :            :                                                 lockdep_is_held(&xa->xa_lock));
    1131                 :            : }
    1132                 :            : 
    1133                 :            : /* Private */
    1134                 :            : static inline void *xa_head_locked(const struct xarray *xa)
    1135                 :            : {
    1136                 :    2166763 :         return rcu_dereference_protected(xa->xa_head,
    1137                 :            :                                                 lockdep_is_held(&xa->xa_lock));
    1138                 :            : }
    1139                 :            : 
    1140                 :            : /* Private */
    1141                 :            : static inline void *xa_entry(const struct xarray *xa,
    1142                 :            :                                 const struct xa_node *node, unsigned int offset)
    1143                 :            : {
    1144                 :            :         XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
    1145                 : 1204171105 :         return rcu_dereference_check(node->slots[offset],
    1146                 :            :                                                 lockdep_is_held(&xa->xa_lock));
    1147                 :            : }
    1148                 :            : 
    1149                 :            : /* Private */
    1150                 :            : static inline void *xa_entry_locked(const struct xarray *xa,
    1151                 :            :                                 const struct xa_node *node, unsigned int offset)
    1152                 :            : {
    1153                 :            :         XA_NODE_BUG_ON(node, offset >= XA_CHUNK_SIZE);
    1154                 :   11602492 :         return rcu_dereference_protected(node->slots[offset],
    1155                 :            :                                                 lockdep_is_held(&xa->xa_lock));
    1156                 :            : }
    1157                 :            : 
    1158                 :            : /* Private */
    1159                 :            : static inline struct xa_node *xa_parent(const struct xarray *xa,
    1160                 :            :                                         const struct xa_node *node)
    1161                 :            : {
    1162                 :    3308108 :         return rcu_dereference_check(node->parent,
    1163                 :            :                                                 lockdep_is_held(&xa->xa_lock));
    1164                 :            : }
    1165                 :            : 
    1166                 :            : /* Private */
    1167                 :            : static inline struct xa_node *xa_parent_locked(const struct xarray *xa,
    1168                 :            :                                         const struct xa_node *node)
    1169                 :            : {
    1170                 :    1123905 :         return rcu_dereference_protected(node->parent,
    1171                 :            :                                                 lockdep_is_held(&xa->xa_lock));
    1172                 :            : }
    1173                 :            : 
    1174                 :            : /* Private */
    1175                 :            : static inline void *xa_mk_node(const struct xa_node *node)
    1176                 :            : {
    1177                 :     469264 :         return (void *)((unsigned long)node | 2);
    1178                 :            : }
    1179                 :            : 
    1180                 :            : /* Private */
    1181                 :            : static inline struct xa_node *xa_to_node(const void *entry)
    1182                 :            : {
    1183                 :  341036917 :         return (struct xa_node *)((unsigned long)entry - 2);
    1184                 :            : }
    1185                 :            : 
    1186                 :            : /* Private */
    1187                 :            : static inline bool xa_is_node(const void *entry)
    1188                 :            : {
    1189   [ #  #  #  #  :  387957634 :         return xa_is_internal(entry) && (unsigned long)entry > 4096;
          #  #  #  #  +  
          +  -  +  #  #  
          #  #  +  +  -  
          +  +  +  -  +  
          +  +  -  +  +  
          +  +  +  +  +  
          +  +  #  #  #  
          #  -  +  #  #  
          -  +  #  #  +  
          +  -  +  +  +  
          +  +  +  +  +  
          +  +  +  +  +  
          #  #  #  #  +  
          -  -  +  +  -  
          -  +  +  -  -  
          +  +  +  -  +  
             +  +  +  + ]
    1190                 :            : }
    1191                 :            : 
    1192                 :            : /* Private */
    1193                 :            : static inline void *xa_mk_sibling(unsigned int offset)
    1194                 :            : {
    1195                 :            :         return xa_mk_internal(offset);
    1196                 :            : }
    1197                 :            : 
    1198                 :            : /* Private */
    1199                 :            : static inline unsigned long xa_to_sibling(const void *entry)
    1200                 :            : {
    1201                 :            :         return xa_to_internal(entry);
    1202                 :            : }
    1203                 :            : 
    1204                 :            : /**
    1205                 :            :  * xa_is_sibling() - Is the entry a sibling entry?
    1206                 :            :  * @entry: Entry retrieved from the XArray
    1207                 :            :  *
    1208                 :            :  * Return: %true if the entry is a sibling entry.
    1209                 :            :  */
    1210                 :            : static inline bool xa_is_sibling(const void *entry)
    1211                 :            : {
    1212                 :            :         return IS_ENABLED(CONFIG_XARRAY_MULTI) && xa_is_internal(entry) &&
    1213                 :            :                 (entry < xa_mk_sibling(XA_CHUNK_SIZE - 1));
    1214                 :            : }
    1215                 :            : 
    1216                 :            : #define XA_RETRY_ENTRY          xa_mk_internal(256)
    1217                 :            : 
    1218                 :            : /**
    1219                 :            :  * xa_is_retry() - Is the entry a retry entry?
    1220                 :            :  * @entry: Entry retrieved from the XArray
    1221                 :            :  *
    1222                 :            :  * Return: %true if the entry is a retry entry.
    1223                 :            :  */
    1224                 :            : static inline bool xa_is_retry(const void *entry)
    1225                 :            : {
    1226                 :  221821286 :         return unlikely(entry == XA_RETRY_ENTRY);
    1227                 :            : }
    1228                 :            : 
    1229                 :            : /**
    1230                 :            :  * xa_is_advanced() - Is the entry only permitted for the advanced API?
    1231                 :            :  * @entry: Entry to be stored in the XArray.
    1232                 :            :  *
    1233                 :            :  * Return: %true if the entry cannot be stored by the normal API.
    1234                 :            :  */
    1235                 :            : static inline bool xa_is_advanced(const void *entry)
    1236                 :            : {
    1237   [ -  +  #  #  :        414 :         return xa_is_internal(entry) && (entry <= XA_RETRY_ENTRY);
          #  #  #  #  #  
          #  #  #  #  #  
                   #  # ]
    1238                 :            : }
    1239                 :            : 
    1240                 :            : /**
    1241                 :            :  * typedef xa_update_node_t - A callback function from the XArray.
    1242                 :            :  * @node: The node which is being processed
    1243                 :            :  *
    1244                 :            :  * This function is called every time the XArray updates the count of
    1245                 :            :  * present and value entries in a node.  It allows advanced users to
    1246                 :            :  * maintain the private_list in the node.
    1247                 :            :  *
    1248                 :            :  * Context: The xa_lock is held and interrupts may be disabled.
    1249                 :            :  *          Implementations should not drop the xa_lock, nor re-enable
    1250                 :            :  *          interrupts.
    1251                 :            :  */
    1252                 :            : typedef void (*xa_update_node_t)(struct xa_node *node);
    1253                 :            : 
    1254                 :            : /*
    1255                 :            :  * The xa_state is opaque to its users.  It contains various different pieces
    1256                 :            :  * of state involved in the current operation on the XArray.  It should be
    1257                 :            :  * declared on the stack and passed between the various internal routines.
    1258                 :            :  * The various elements in it should not be accessed directly, but only
    1259                 :            :  * through the provided accessor functions.  The below documentation is for
    1260                 :            :  * the benefit of those working on the code, not for users of the XArray.
    1261                 :            :  *
    1262                 :            :  * @xa_node usually points to the xa_node containing the slot we're operating
    1263                 :            :  * on (and @xa_offset is the offset in the slots array).  If there is a
    1264                 :            :  * single entry in the array at index 0, there are no allocated xa_nodes to
    1265                 :            :  * point to, and so we store %NULL in @xa_node.  @xa_node is set to
    1266                 :            :  * the value %XAS_RESTART if the xa_state is not walked to the correct
    1267                 :            :  * position in the tree of nodes for this operation.  If an error occurs
    1268                 :            :  * during an operation, it is set to an %XAS_ERROR value.  If we run off the
    1269                 :            :  * end of the allocated nodes, it is set to %XAS_BOUNDS.
    1270                 :            :  */
    1271                 :            : struct xa_state {
    1272                 :            :         struct xarray *xa;
    1273                 :            :         unsigned long xa_index;
    1274                 :            :         unsigned char xa_shift;
    1275                 :            :         unsigned char xa_sibs;
    1276                 :            :         unsigned char xa_offset;
    1277                 :            :         unsigned char xa_pad;           /* Helps gcc generate better code */
    1278                 :            :         struct xa_node *xa_node;
    1279                 :            :         struct xa_node *xa_alloc;
    1280                 :            :         xa_update_node_t xa_update;
    1281                 :            : };
    1282                 :            : 
    1283                 :            : /*
    1284                 :            :  * We encode errnos in the xas->xa_node.  If an error has happened, we need to
    1285                 :            :  * drop the lock to fix it, and once we've done so the xa_state is invalid.
    1286                 :            :  */
    1287                 :            : #define XA_ERROR(errno) ((struct xa_node *)(((unsigned long)errno << 2) | 2UL))
    1288                 :            : #define XAS_BOUNDS      ((struct xa_node *)1UL)
    1289                 :            : #define XAS_RESTART     ((struct xa_node *)3UL)
    1290                 :            : 
    1291                 :            : #define __XA_STATE(array, index, shift, sibs)  {        \
    1292                 :            :         .xa = array,                                    \
    1293                 :            :         .xa_index = index,                              \
    1294                 :            :         .xa_shift = shift,                              \
    1295                 :            :         .xa_sibs = sibs,                                \
    1296                 :            :         .xa_offset = 0,                                 \
    1297                 :            :         .xa_pad = 0,                                    \
    1298                 :            :         .xa_node = XAS_RESTART,                         \
    1299                 :            :         .xa_alloc = NULL,                               \
    1300                 :            :         .xa_update = NULL                               \
    1301                 :            : }
    1302                 :            : 
    1303                 :            : /**
    1304                 :            :  * XA_STATE() - Declare an XArray operation state.
    1305                 :            :  * @name: Name of this operation state (usually xas).
    1306                 :            :  * @array: Array to operate on.
    1307                 :            :  * @index: Initial index of interest.
    1308                 :            :  *
    1309                 :            :  * Declare and initialise an xa_state on the stack.
    1310                 :            :  */
    1311                 :            : #define XA_STATE(name, array, index)                            \
    1312                 :            :         struct xa_state name = __XA_STATE(array, index, 0, 0)
    1313                 :            : 
    1314                 :            : /**
    1315                 :            :  * XA_STATE_ORDER() - Declare an XArray operation state.
    1316                 :            :  * @name: Name of this operation state (usually xas).
    1317                 :            :  * @array: Array to operate on.
    1318                 :            :  * @index: Initial index of interest.
    1319                 :            :  * @order: Order of entry.
    1320                 :            :  *
    1321                 :            :  * Declare and initialise an xa_state on the stack.  This variant of
    1322                 :            :  * XA_STATE() allows you to specify the 'order' of the element you
    1323                 :            :  * want to operate on.`
    1324                 :            :  */
    1325                 :            : #define XA_STATE_ORDER(name, array, index, order)               \
    1326                 :            :         struct xa_state name = __XA_STATE(array,                \
    1327                 :            :                         (index >> order) << order,          \
    1328                 :            :                         order - (order % XA_CHUNK_SHIFT),       \
    1329                 :            :                         (1U << (order % XA_CHUNK_SHIFT)) - 1)
    1330                 :            : 
    1331                 :            : #define xas_marked(xas, mark)   xa_marked((xas)->xa, (mark))
    1332                 :            : #define xas_trylock(xas)        xa_trylock((xas)->xa)
    1333                 :            : #define xas_lock(xas)           xa_lock((xas)->xa)
    1334                 :            : #define xas_unlock(xas)         xa_unlock((xas)->xa)
    1335                 :            : #define xas_lock_bh(xas)        xa_lock_bh((xas)->xa)
    1336                 :            : #define xas_unlock_bh(xas)      xa_unlock_bh((xas)->xa)
    1337                 :            : #define xas_lock_irq(xas)       xa_lock_irq((xas)->xa)
    1338                 :            : #define xas_unlock_irq(xas)     xa_unlock_irq((xas)->xa)
    1339                 :            : #define xas_lock_irqsave(xas, flags) \
    1340                 :            :                                 xa_lock_irqsave((xas)->xa, flags)
    1341                 :            : #define xas_unlock_irqrestore(xas, flags) \
    1342                 :            :                                 xa_unlock_irqrestore((xas)->xa, flags)
    1343                 :            : 
    1344                 :            : /**
    1345                 :            :  * xas_error() - Return an errno stored in the xa_state.
    1346                 :            :  * @xas: XArray operation state.
    1347                 :            :  *
    1348                 :            :  * Return: 0 if no error has been noted.  A negative errno if one has.
    1349                 :            :  */
    1350                 :            : static inline int xas_error(const struct xa_state *xas)
    1351                 :            : {
    1352                 :  109299309 :         return xa_err(xas->xa_node);
    1353                 :            : }
    1354                 :            : 
    1355                 :            : /**
    1356                 :            :  * xas_set_err() - Note an error in the xa_state.
    1357                 :            :  * @xas: XArray operation state.
    1358                 :            :  * @err: Negative error number.
    1359                 :            :  *
    1360                 :            :  * Only call this function with a negative @err; zero or positive errors
    1361                 :            :  * will probably not behave the way you think they should.  If you want
    1362                 :            :  * to clear the error from an xa_state, use xas_reset().
    1363                 :            :  */
    1364                 :            : static inline void xas_set_err(struct xa_state *xas, long err)
    1365                 :            : {
    1366                 :      55892 :         xas->xa_node = XA_ERROR(err);
    1367                 :            : }
    1368                 :            : 
    1369                 :            : /**
    1370                 :            :  * xas_invalid() - Is the xas in a retry or error state?
    1371                 :            :  * @xas: XArray operation state.
    1372                 :            :  *
    1373                 :            :  * Return: %true if the xas cannot be used for operations.
    1374                 :            :  */
    1375                 :            : static inline bool xas_invalid(const struct xa_state *xas)
    1376                 :            : {
    1377                 :  148783186 :         return (unsigned long)xas->xa_node & 3;
    1378                 :            : }
    1379                 :            : 
    1380                 :            : /**
    1381                 :            :  * xas_valid() - Is the xas a valid cursor into the array?
    1382                 :            :  * @xas: XArray operation state.
    1383                 :            :  *
    1384                 :            :  * Return: %true if the xas can be used for operations.
    1385                 :            :  */
    1386                 :            : static inline bool xas_valid(const struct xa_state *xas)
    1387                 :            : {
    1388                 :            :         return !xas_invalid(xas);
    1389                 :            : }
    1390                 :            : 
    1391                 :            : /**
    1392                 :            :  * xas_is_node() - Does the xas point to a node?
    1393                 :            :  * @xas: XArray operation state.
    1394                 :            :  *
    1395                 :            :  * Return: %true if the xas currently references a node.
    1396                 :            :  */
    1397                 :            : static inline bool xas_is_node(const struct xa_state *xas)
    1398                 :            : {
    1399   [ +  +  +  + ]:    1249961 :         return xas_valid(xas) && xas->xa_node;
    1400                 :            : }
    1401                 :            : 
    1402                 :            : /* True if the pointer is something other than a node */
    1403                 :            : static inline bool xas_not_node(struct xa_node *node)
    1404                 :            : {
    1405   [ +  +  +  +  :  181763389 :         return ((unsigned long)node & 3) || !node;
          +  +  +  +  +  
          +  +  +  +  +  
          +  +  #  #  #  
                      # ]
    1406                 :            : }
    1407                 :            : 
    1408                 :            : /* True if the node represents RESTART or an error */
    1409                 :            : static inline bool xas_frozen(struct xa_node *node)
    1410                 :            : {
    1411                 :     185284 :         return (unsigned long)node & 2;
    1412                 :            : }
    1413                 :            : 
    1414                 :            : /* True if the node represents head-of-tree, RESTART or BOUNDS */
    1415                 :            : static inline bool xas_top(struct xa_node *node)
    1416                 :            : {
    1417                 :            :         return node <= XAS_RESTART;
    1418                 :            : }
    1419                 :            : 
    1420                 :            : /**
    1421                 :            :  * xas_reset() - Reset an XArray operation state.
    1422                 :            :  * @xas: XArray operation state.
    1423                 :            :  *
    1424                 :            :  * Resets the error or walk state of the @xas so future walks of the
    1425                 :            :  * array will start from the root.  Use this if you have dropped the
    1426                 :            :  * xarray lock and want to reuse the xa_state.
    1427                 :            :  *
    1428                 :            :  * Context: Any context.
    1429                 :            :  */
    1430                 :            : static inline void xas_reset(struct xa_state *xas)
    1431                 :            : {
    1432                 :   33982600 :         xas->xa_node = XAS_RESTART;
    1433                 :            : }
    1434                 :            : 
    1435                 :            : /**
    1436                 :            :  * xas_retry() - Retry the operation if appropriate.
    1437                 :            :  * @xas: XArray operation state.
    1438                 :            :  * @entry: Entry from xarray.
    1439                 :            :  *
    1440                 :            :  * The advanced functions may sometimes return an internal entry, such as
    1441                 :            :  * a retry entry or a zero entry.  This function sets up the @xas to restart
    1442                 :            :  * the walk from the head of the array if needed.
    1443                 :            :  *
    1444                 :            :  * Context: Any context.
    1445                 :            :  * Return: true if the operation needs to be retried.
    1446                 :            :  */
    1447                 :            : static inline bool xas_retry(struct xa_state *xas, const void *entry)
    1448                 :            : {
    1449   [ +  -  +  -  :  221803916 :         if (xa_is_zero(entry))
          #  #  +  -  +  
             +  +  +  #  
                      # ]
    1450                 :            :                 return true;
    1451   [ -  +  -  +  :  221821286 :         if (!xa_is_retry(entry))
          #  #  -  +  -  
             +  -  +  #  
                      # ]
    1452                 :            :                 return false;
    1453                 :            :         xas_reset(xas);
    1454                 :            :         return true;
    1455                 :            : }
    1456                 :            : 
    1457                 :            : void *xas_load(struct xa_state *);
    1458                 :            : void *xas_store(struct xa_state *, void *entry);
    1459                 :            : void *xas_find(struct xa_state *, unsigned long max);
    1460                 :            : void *xas_find_conflict(struct xa_state *);
    1461                 :            : 
    1462                 :            : bool xas_get_mark(const struct xa_state *, xa_mark_t);
    1463                 :            : void xas_set_mark(const struct xa_state *, xa_mark_t);
    1464                 :            : void xas_clear_mark(const struct xa_state *, xa_mark_t);
    1465                 :            : void *xas_find_marked(struct xa_state *, unsigned long max, xa_mark_t);
    1466                 :            : void xas_init_marks(const struct xa_state *);
    1467                 :            : 
    1468                 :            : bool xas_nomem(struct xa_state *, gfp_t);
    1469                 :            : void xas_pause(struct xa_state *);
    1470                 :            : 
    1471                 :            : void xas_create_range(struct xa_state *);
    1472                 :            : 
    1473                 :            : /**
    1474                 :            :  * xas_reload() - Refetch an entry from the xarray.
    1475                 :            :  * @xas: XArray operation state.
    1476                 :            :  *
    1477                 :            :  * Use this function to check that a previously loaded entry still has
    1478                 :            :  * the same value.  This is useful for the lockless pagecache lookup where
    1479                 :            :  * we walk the array with only the RCU lock to protect us, lock the page,
    1480                 :            :  * then check that the page hasn't moved since we looked it up.
    1481                 :            :  *
    1482                 :            :  * The caller guarantees that @xas is still valid.  If it may be in an
    1483                 :            :  * error or restart state, call xas_load() instead.
    1484                 :            :  *
    1485                 :            :  * Return: The entry at this location in the xarray.
    1486                 :            :  */
    1487                 :            : static inline void *xas_reload(struct xa_state *xas)
    1488                 :            : {
    1489                 :  206455690 :         struct xa_node *node = xas->xa_node;
    1490                 :            : 
    1491   [ +  +  +  +  :  207030229 :         if (node)
          #  #  +  +  +  
                +  +  + ]
    1492                 :  205259280 :                 return xa_entry(xas->xa, node, xas->xa_offset);
    1493                 :    1770949 :         return xa_head(xas->xa);
    1494                 :            : }
    1495                 :            : 
    1496                 :            : /**
    1497                 :            :  * xas_set() - Set up XArray operation state for a different index.
    1498                 :            :  * @xas: XArray operation state.
    1499                 :            :  * @index: New index into the XArray.
    1500                 :            :  *
    1501                 :            :  * Move the operation state to refer to a different index.  This will
    1502                 :            :  * have the effect of starting a walk from the top; see xas_next()
    1503                 :            :  * to move to an adjacent index.
    1504                 :            :  */
    1505                 :            : static inline void xas_set(struct xa_state *xas, unsigned long index)
    1506                 :            : {
    1507                 :     871256 :         xas->xa_index = index;
    1508                 :     871256 :         xas->xa_node = XAS_RESTART;
    1509                 :            : }
    1510                 :            : 
    1511                 :            : /**
    1512                 :            :  * xas_set_order() - Set up XArray operation state for a multislot entry.
    1513                 :            :  * @xas: XArray operation state.
    1514                 :            :  * @index: Target of the operation.
    1515                 :            :  * @order: Entry occupies 2^@order indices.
    1516                 :            :  */
    1517                 :            : static inline void xas_set_order(struct xa_state *xas, unsigned long index,
    1518                 :            :                                         unsigned int order)
    1519                 :            : {
    1520                 :            : #ifdef CONFIG_XARRAY_MULTI
    1521                 :            :         xas->xa_index = order < BITS_PER_LONG ? (index >> order) << order : 0;
    1522                 :            :         xas->xa_shift = order - (order % XA_CHUNK_SHIFT);
    1523                 :            :         xas->xa_sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
    1524                 :            :         xas->xa_node = XAS_RESTART;
    1525                 :            : #else
    1526         [ -  + ]:     871256 :         BUG_ON(order > 0);
    1527                 :            :         xas_set(xas, index);
    1528                 :            : #endif
    1529                 :            : }
    1530                 :            : 
    1531                 :            : /**
    1532                 :            :  * xas_set_update() - Set up XArray operation state for a callback.
    1533                 :            :  * @xas: XArray operation state.
    1534                 :            :  * @update: Function to call when updating a node.
    1535                 :            :  *
    1536                 :            :  * The XArray can notify a caller after it has updated an xa_node.
    1537                 :            :  * This is advanced functionality and is only needed by the page cache.
    1538                 :            :  */
    1539                 :            : static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update)
    1540                 :            : {
    1541                 :    8318935 :         xas->xa_update = update;
    1542                 :            : }
    1543                 :            : 
    1544                 :            : /**
    1545                 :            :  * xas_next_entry() - Advance iterator to next present entry.
    1546                 :            :  * @xas: XArray operation state.
    1547                 :            :  * @max: Highest index to return.
    1548                 :            :  *
    1549                 :            :  * xas_next_entry() is an inline function to optimise xarray traversal for
    1550                 :            :  * speed.  It is equivalent to calling xas_find(), and will call xas_find()
    1551                 :            :  * for all the hard cases.
    1552                 :            :  *
    1553                 :            :  * Return: The next present entry after the one currently referred to by @xas.
    1554                 :            :  */
    1555                 :  178886345 : static inline void *xas_next_entry(struct xa_state *xas, unsigned long max)
    1556                 :            : {
    1557                 :  178886345 :         struct xa_node *node = xas->xa_node;
    1558                 :            :         void *entry;
    1559                 :            : 
    1560   [ +  +  +  +  :  178886345 :         if (unlikely(xas_not_node(node) || node->shift ||
             +  +  +  + ]
    1561                 :            :                         xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)))
    1562                 :     308680 :                 return xas_find(xas, max);
    1563                 :            : 
    1564                 :            :         do {
    1565         [ +  + ]:  181812169 :                 if (unlikely(xas->xa_index >= max))
    1566                 :   14023192 :                         return xas_find(xas, max);
    1567         [ +  + ]:  167788977 :                 if (unlikely(xas->xa_offset == XA_CHUNK_MASK))
    1568                 :    1111933 :                         return xas_find(xas, max);
    1569                 :  166677044 :                 entry = xa_entry(xas->xa, node, xas->xa_offset + 1);
    1570         [ -  + ]:  166677044 :                 if (unlikely(xa_is_internal(entry)))
    1571                 :          0 :                         return xas_find(xas, max);
    1572                 :  166677044 :                 xas->xa_offset++;
    1573                 :  166677044 :                 xas->xa_index++;
    1574         [ +  + ]:  166677044 :         } while (!entry);
    1575                 :            : 
    1576                 :  163442540 :         return entry;
    1577                 :            : }
    1578                 :            : 
    1579                 :            : /* Private */
    1580                 :            : static inline unsigned int xas_find_chunk(struct xa_state *xas, bool advance,
    1581                 :            :                 xa_mark_t mark)
    1582                 :            : {
    1583                 :     666581 :         unsigned long *addr = xas->xa_node->marks[(__force unsigned)mark];
    1584                 :     666581 :         unsigned int offset = xas->xa_offset;
    1585                 :            : 
    1586         [ -  + ]:     521967 :         if (advance)
    1587                 :     144614 :                 offset++;
    1588                 :            :         if (XA_CHUNK_SIZE == BITS_PER_LONG) {
    1589                 :            :                 if (offset < XA_CHUNK_SIZE) {
    1590                 :            :                         unsigned long data = *addr & (~0UL << offset);
    1591                 :            :                         if (data)
    1592                 :            :                                 return __ffs(data);
    1593                 :            :                 }
    1594                 :            :                 return XA_CHUNK_SIZE;
    1595                 :            :         }
    1596                 :            : 
    1597                 :     666581 :         return find_next_bit(addr, XA_CHUNK_SIZE, offset);
    1598                 :            : }
    1599                 :            : 
    1600                 :            : /**
    1601                 :            :  * xas_next_marked() - Advance iterator to next marked entry.
    1602                 :            :  * @xas: XArray operation state.
    1603                 :            :  * @max: Highest index to return.
    1604                 :            :  * @mark: Mark to search for.
    1605                 :            :  *
    1606                 :            :  * xas_next_marked() is an inline function to optimise xarray traversal for
    1607                 :            :  * speed.  It is equivalent to calling xas_find_marked(), and will call
    1608                 :            :  * xas_find_marked() for all the hard cases.
    1609                 :            :  *
    1610                 :            :  * Return: The next marked entry after the one currently referred to by @xas.
    1611                 :            :  */
    1612                 :     159774 : static inline void *xas_next_marked(struct xa_state *xas, unsigned long max,
    1613                 :            :                                                                 xa_mark_t mark)
    1614                 :            : {
    1615                 :     159774 :         struct xa_node *node = xas->xa_node;
    1616                 :            :         void *entry;
    1617                 :            :         unsigned int offset;
    1618                 :            : 
    1619   [ +  +  -  + ]:     159774 :         if (unlikely(xas_not_node(node) || node->shift))
    1620                 :      15160 :                 return xas_find_marked(xas, max, mark);
    1621                 :            :         offset = xas_find_chunk(xas, true, mark);
    1622                 :     144614 :         xas->xa_offset = offset;
    1623                 :     144614 :         xas->xa_index = (xas->xa_index & ~XA_CHUNK_MASK) + offset;
    1624         [ +  + ]:     144614 :         if (xas->xa_index > max)
    1625                 :            :                 return NULL;
    1626         [ +  + ]:     143215 :         if (offset == XA_CHUNK_SIZE)
    1627                 :      51985 :                 return xas_find_marked(xas, max, mark);
    1628                 :            :         entry = xa_entry(xas->xa, node, offset);
    1629         [ -  + ]:      91230 :         if (!entry)
    1630                 :          0 :                 return xas_find_marked(xas, max, mark);
    1631                 :            :         return entry;
    1632                 :            : }
    1633                 :            : 
    1634                 :            : /*
    1635                 :            :  * If iterating while holding a lock, drop the lock and reschedule
    1636                 :            :  * every %XA_CHECK_SCHED loops.
    1637                 :            :  */
    1638                 :            : enum {
    1639                 :            :         XA_CHECK_SCHED = 4096,
    1640                 :            : };
    1641                 :            : 
    1642                 :            : /**
    1643                 :            :  * xas_for_each() - Iterate over a range of an XArray.
    1644                 :            :  * @xas: XArray operation state.
    1645                 :            :  * @entry: Entry retrieved from the array.
    1646                 :            :  * @max: Maximum index to retrieve from array.
    1647                 :            :  *
    1648                 :            :  * The loop body will be executed for each entry present in the xarray
    1649                 :            :  * between the current xas position and @max.  @entry will be set to
    1650                 :            :  * the entry retrieved from the xarray.  It is safe to delete entries
    1651                 :            :  * from the array in the loop body.  You should hold either the RCU lock
    1652                 :            :  * or the xa_lock while iterating.  If you need to drop the lock, call
    1653                 :            :  * xas_pause() first.
    1654                 :            :  */
    1655                 :            : #define xas_for_each(xas, entry, max) \
    1656                 :            :         for (entry = xas_find(xas, max); entry; \
    1657                 :            :              entry = xas_next_entry(xas, max))
    1658                 :            : 
    1659                 :            : /**
    1660                 :            :  * xas_for_each_marked() - Iterate over a range of an XArray.
    1661                 :            :  * @xas: XArray operation state.
    1662                 :            :  * @entry: Entry retrieved from the array.
    1663                 :            :  * @max: Maximum index to retrieve from array.
    1664                 :            :  * @mark: Mark to search for.
    1665                 :            :  *
    1666                 :            :  * The loop body will be executed for each marked entry in the xarray
    1667                 :            :  * between the current xas position and @max.  @entry will be set to
    1668                 :            :  * the entry retrieved from the xarray.  It is safe to delete entries
    1669                 :            :  * from the array in the loop body.  You should hold either the RCU lock
    1670                 :            :  * or the xa_lock while iterating.  If you need to drop the lock, call
    1671                 :            :  * xas_pause() first.
    1672                 :            :  */
    1673                 :            : #define xas_for_each_marked(xas, entry, max, mark) \
    1674                 :            :         for (entry = xas_find_marked(xas, max, mark); entry; \
    1675                 :            :              entry = xas_next_marked(xas, max, mark))
    1676                 :            : 
    1677                 :            : /**
    1678                 :            :  * xas_for_each_conflict() - Iterate over a range of an XArray.
    1679                 :            :  * @xas: XArray operation state.
    1680                 :            :  * @entry: Entry retrieved from the array.
    1681                 :            :  *
    1682                 :            :  * The loop body will be executed for each entry in the XArray that lies
    1683                 :            :  * within the range specified by @xas.  If the loop completes successfully,
    1684                 :            :  * any entries that lie in this range will be replaced by @entry.  The caller
    1685                 :            :  * may break out of the loop; if they do so, the contents of the XArray will
    1686                 :            :  * be unchanged.  The operation may fail due to an out of memory condition.
    1687                 :            :  * The caller may also call xa_set_err() to exit the loop while setting an
    1688                 :            :  * error to record the reason.
    1689                 :            :  */
    1690                 :            : #define xas_for_each_conflict(xas, entry) \
    1691                 :            :         while ((entry = xas_find_conflict(xas)))
    1692                 :            : 
    1693                 :            : void *__xas_next(struct xa_state *);
    1694                 :            : void *__xas_prev(struct xa_state *);
    1695                 :            : 
    1696                 :            : /**
    1697                 :            :  * xas_prev() - Move iterator to previous index.
    1698                 :            :  * @xas: XArray operation state.
    1699                 :            :  *
    1700                 :            :  * If the @xas was in an error state, it will remain in an error state
    1701                 :            :  * and this function will return %NULL.  If the @xas has never been walked,
    1702                 :            :  * it will have the effect of calling xas_load().  Otherwise one will be
    1703                 :            :  * subtracted from the index and the state will be walked to the correct
    1704                 :            :  * location in the array for the next operation.
    1705                 :            :  *
    1706                 :            :  * If the iterator was referencing index 0, this function wraps
    1707                 :            :  * around to %ULONG_MAX.
    1708                 :            :  *
    1709                 :            :  * Return: The entry at the new index.  This may be %NULL or an internal
    1710                 :            :  * entry.
    1711                 :            :  */
    1712                 :      48627 : static inline void *xas_prev(struct xa_state *xas)
    1713                 :            : {
    1714                 :      48627 :         struct xa_node *node = xas->xa_node;
    1715                 :            : 
    1716   [ +  +  +  -  :      48627 :         if (unlikely(xas_not_node(node) || node->shift ||
             +  +  +  + ]
    1717                 :            :                                 xas->xa_offset == 0))
    1718                 :      48166 :                 return __xas_prev(xas);
    1719                 :            : 
    1720                 :        461 :         xas->xa_index--;
    1721                 :        461 :         xas->xa_offset--;
    1722                 :        922 :         return xa_entry(xas->xa, node, xas->xa_offset);
    1723                 :            : }
    1724                 :            : 
    1725                 :            : /**
    1726                 :            :  * xas_next() - Move state to next index.
    1727                 :            :  * @xas: XArray operation state.
    1728                 :            :  *
    1729                 :            :  * If the @xas was in an error state, it will remain in an error state
    1730                 :            :  * and this function will return %NULL.  If the @xas has never been walked,
    1731                 :            :  * it will have the effect of calling xas_load().  Otherwise one will be
    1732                 :            :  * added to the index and the state will be walked to the correct
    1733                 :            :  * location in the array for the next operation.
    1734                 :            :  *
    1735                 :            :  * If the iterator was referencing index %ULONG_MAX, this function wraps
    1736                 :            :  * around to 0.
    1737                 :            :  *
    1738                 :            :  * Return: The entry at the new index.  This may be %NULL or an internal
    1739                 :            :  * entry.
    1740                 :            :  */
    1741                 :    2227382 : static inline void *xas_next(struct xa_state *xas)
    1742                 :            : {
    1743                 :    2227382 :         struct xa_node *node = xas->xa_node;
    1744                 :            : 
    1745   [ +  +  +  +  :    2227382 :         if (unlikely(xas_not_node(node) || node->shift ||
             +  +  +  + ]
    1746                 :            :                                 xas->xa_offset == XA_CHUNK_MASK))
    1747                 :     136868 :                 return __xas_next(xas);
    1748                 :            : 
    1749                 :    2090514 :         xas->xa_index++;
    1750                 :    2090514 :         xas->xa_offset++;
    1751                 :    4181028 :         return xa_entry(xas->xa, node, xas->xa_offset);
    1752                 :            : }
    1753                 :            : 
    1754                 :            : #endif /* _LINUX_XARRAY_H */

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