LCOV - code coverage report
Current view: top level - include/linux - list.h (source / functions) Hit Total Coverage
Test: gcov_data_raspi2_real_modules_combined.info Lines: 79 94 84.0 %
Date: 2020-09-30 20:25:40 Functions: 6 8 75.0 %
Branches: 84 140 60.0 %

           Branch data     Line data    Source code
       1                 :            : /* SPDX-License-Identifier: GPL-2.0 */
       2                 :            : #ifndef _LINUX_LIST_H
       3                 :            : #define _LINUX_LIST_H
       4                 :            : 
       5                 :            : #include <linux/types.h>
       6                 :            : #include <linux/stddef.h>
       7                 :            : #include <linux/poison.h>
       8                 :            : #include <linux/const.h>
       9                 :            : #include <linux/kernel.h>
      10                 :            : 
      11                 :            : /*
      12                 :            :  * Simple doubly linked list implementation.
      13                 :            :  *
      14                 :            :  * Some of the internal functions ("__xxx") are useful when
      15                 :            :  * manipulating whole lists rather than single entries, as
      16                 :            :  * sometimes we already know the next/prev entries and we can
      17                 :            :  * generate better code by using them directly rather than
      18                 :            :  * using the generic single-entry routines.
      19                 :            :  */
      20                 :            : 
      21                 :            : #define LIST_HEAD_INIT(name) { &(name), &(name) }
      22                 :            : 
      23                 :            : #define LIST_HEAD(name) \
      24                 :            :         struct list_head name = LIST_HEAD_INIT(name)
      25                 :            : 
      26                 :      90044 : static inline void INIT_LIST_HEAD(struct list_head *list)
      27                 :            : {
      28                 :  291924076 :         WRITE_ONCE(list->next, list);
      29                 :  313955239 :         list->prev = list;
      30                 :      90044 : }
      31                 :            : 
      32                 :            : #ifdef CONFIG_DEBUG_LIST
      33                 :            : extern bool __list_add_valid(struct list_head *new,
      34                 :            :                               struct list_head *prev,
      35                 :            :                               struct list_head *next);
      36                 :            : extern bool __list_del_entry_valid(struct list_head *entry);
      37                 :            : #else
      38                 :            : static inline bool __list_add_valid(struct list_head *new,
      39                 :            :                                 struct list_head *prev,
      40                 :            :                                 struct list_head *next)
      41                 :            : {
      42                 :            :         return true;
      43                 :            : }
      44                 :            : static inline bool __list_del_entry_valid(struct list_head *entry)
      45                 :            : {
      46                 :            :         return true;
      47                 :            : }
      48                 :            : #endif
      49                 :            : 
      50                 :            : /*
      51                 :            :  * Insert a new entry between two known consecutive entries.
      52                 :            :  *
      53                 :            :  * This is only for internal list manipulation where we know
      54                 :            :  * the prev/next entries already!
      55                 :            :  */
      56                 :            : static inline void __list_add(struct list_head *new,
      57                 :            :                               struct list_head *prev,
      58                 :            :                               struct list_head *next)
      59                 :            : {
      60                 :            :         if (!__list_add_valid(new, prev, next))
      61                 :            :                 return;
      62                 :            : 
      63                 :  241360377 :         next->prev = new;
      64                 :  241360377 :         new->next = next;
      65                 :  241360377 :         new->prev = prev;
      66                 :  237132693 :         WRITE_ONCE(prev->next, new);
      67                 :            : }
      68                 :            : 
      69                 :            : /**
      70                 :            :  * list_add - add a new entry
      71                 :            :  * @new: new entry to be added
      72                 :            :  * @head: list head to add it after
      73                 :            :  *
      74                 :            :  * Insert a new entry after the specified head.
      75                 :            :  * This is good for implementing stacks.
      76                 :            :  */
      77                 :   33392779 : static inline void list_add(struct list_head *new, struct list_head *head)
      78                 :            : {
      79                 :  182833747 :         __list_add(new, head, head->next);
      80                 :   33392779 : }
      81                 :            : 
      82                 :            : 
      83                 :            : /**
      84                 :            :  * list_add_tail - add a new entry
      85                 :            :  * @new: new entry to be added
      86                 :            :  * @head: list head to add it before
      87                 :            :  *
      88                 :            :  * Insert a new entry before the specified head.
      89                 :            :  * This is useful for implementing queues.
      90                 :            :  */
      91                 :          0 : static inline void list_add_tail(struct list_head *new, struct list_head *head)
      92                 :            : {
      93                 :   58092461 :         __list_add(new, head->prev, head);
      94                 :          0 : }
      95                 :            : 
      96                 :            : /*
      97                 :            :  * Delete a list entry by making the prev/next entries
      98                 :            :  * point to each other.
      99                 :            :  *
     100                 :            :  * This is only for internal list manipulation where we know
     101                 :            :  * the prev/next entries already!
     102                 :            :  */
     103                 :       5129 : static inline void __list_del(struct list_head * prev, struct list_head * next)
     104                 :            : {
     105                 :  184743263 :         next->prev = prev;
     106                 :  184743263 :         WRITE_ONCE(prev->next, next);
     107                 :       5129 : }
     108                 :            : 
     109                 :            : /*
     110                 :            :  * Delete a list entry and clear the 'prev' pointer.
     111                 :            :  *
     112                 :            :  * This is a special-purpose list clearing method used in the networking code
     113                 :            :  * for lists allocated as per-cpu, where we don't want to incur the extra
     114                 :            :  * WRITE_ONCE() overhead of a regular list_del_init(). The code that uses this
     115                 :            :  * needs to check the node 'prev' pointer instead of calling list_empty().
     116                 :            :  */
     117                 :            : static inline void __list_del_clearprev(struct list_head *entry)
     118                 :            : {
     119                 :          0 :         __list_del(entry->prev, entry->next);
     120                 :          0 :         entry->prev = NULL;
     121                 :            : }
     122                 :            : 
     123                 :            : /**
     124                 :            :  * list_del - deletes entry from list.
     125                 :            :  * @entry: the element to delete from the list.
     126                 :            :  * Note: list_empty() on entry does not return true after this, the entry is
     127                 :            :  * in an undefined state.
     128                 :            :  */
     129                 :            : static inline void __list_del_entry(struct list_head *entry)
     130                 :            : {
     131                 :            :         if (!__list_del_entry_valid(entry))
     132                 :            :                 return;
     133                 :            : 
     134                 :  184738134 :         __list_del(entry->prev, entry->next);
     135                 :            : }
     136                 :            : 
     137                 :   22340655 : static inline void list_del(struct list_head *entry)
     138                 :            : {
     139                 :            :         __list_del_entry(entry);
     140                 :  136451112 :         entry->next = LIST_POISON1;
     141                 :  136451112 :         entry->prev = LIST_POISON2;
     142                 :   22340655 : }
     143                 :            : 
     144                 :            : /**
     145                 :            :  * list_replace - replace old entry by new one
     146                 :            :  * @old : the element to be replaced
     147                 :            :  * @new : the new element to insert
     148                 :            :  *
     149                 :            :  * If @old was empty, it will be overwritten.
     150                 :            :  */
     151                 :            : static inline void list_replace(struct list_head *old,
     152                 :            :                                 struct list_head *new)
     153                 :            : {
     154                 :    1178805 :         new->next = old->next;
     155                 :    1178805 :         new->next->prev = new;
     156                 :    1178805 :         new->prev = old->prev;
     157                 :    1178805 :         new->prev->next = new;
     158                 :            : }
     159                 :            : 
     160                 :            : static inline void list_replace_init(struct list_head *old,
     161                 :            :                                         struct list_head *new)
     162                 :            : {
     163                 :            :         list_replace(old, new);
     164                 :            :         INIT_LIST_HEAD(old);
     165                 :            : }
     166                 :            : 
     167                 :            : /**
     168                 :            :  * list_swap - replace entry1 with entry2 and re-add entry1 at entry2's position
     169                 :            :  * @entry1: the location to place entry2
     170                 :            :  * @entry2: the location to place entry1
     171                 :            :  */
     172                 :            : static inline void list_swap(struct list_head *entry1,
     173                 :            :                              struct list_head *entry2)
     174                 :            : {
     175                 :            :         struct list_head *pos = entry2->prev;
     176                 :            : 
     177                 :            :         list_del(entry2);
     178                 :            :         list_replace(entry1, entry2);
     179                 :            :         if (pos == entry1)
     180                 :            :                 pos = entry2;
     181                 :            :         list_add(entry1, pos);
     182                 :            : }
     183                 :            : 
     184                 :            : /**
     185                 :            :  * list_del_init - deletes entry from list and reinitialize it.
     186                 :            :  * @entry: the element to delete from the list.
     187                 :            :  */
     188                 :            : static inline void list_del_init(struct list_head *entry)
     189                 :            : {
     190                 :            :         __list_del_entry(entry);
     191                 :            :         INIT_LIST_HEAD(entry);
     192                 :            : }
     193                 :            : 
     194                 :            : /**
     195                 :            :  * list_move - delete from one list and add as another's head
     196                 :            :  * @list: the entry to move
     197                 :            :  * @head: the head that will precede our entry
     198                 :            :  */
     199                 :            : static inline void list_move(struct list_head *list, struct list_head *head)
     200                 :            : {
     201                 :            :         __list_del_entry(list);
     202                 :            :         list_add(list, head);
     203                 :            : }
     204                 :            : 
     205                 :            : /**
     206                 :            :  * list_move_tail - delete from one list and add as another's tail
     207                 :            :  * @list: the entry to move
     208                 :            :  * @head: the head that will follow our entry
     209                 :            :  */
     210                 :            : static inline void list_move_tail(struct list_head *list,
     211                 :            :                                   struct list_head *head)
     212                 :            : {
     213                 :            :         __list_del_entry(list);
     214                 :            :         list_add_tail(list, head);
     215                 :            : }
     216                 :            : 
     217                 :            : /**
     218                 :            :  * list_bulk_move_tail - move a subsection of a list to its tail
     219                 :            :  * @head: the head that will follow our entry
     220                 :            :  * @first: first entry to move
     221                 :            :  * @last: last entry to move, can be the same as first
     222                 :            :  *
     223                 :            :  * Move all entries between @first and including @last before @head.
     224                 :            :  * All three entries must belong to the same linked list.
     225                 :            :  */
     226                 :            : static inline void list_bulk_move_tail(struct list_head *head,
     227                 :            :                                        struct list_head *first,
     228                 :            :                                        struct list_head *last)
     229                 :            : {
     230                 :            :         first->prev->next = last->next;
     231                 :            :         last->next->prev = first->prev;
     232                 :            : 
     233                 :            :         head->prev->next = first;
     234                 :            :         first->prev = head->prev;
     235                 :            : 
     236                 :            :         last->next = head;
     237                 :            :         head->prev = last;
     238                 :            : }
     239                 :            : 
     240                 :            : /**
     241                 :            :  * list_is_first -- tests whether @list is the first entry in list @head
     242                 :            :  * @list: the entry to test
     243                 :            :  * @head: the head of the list
     244                 :            :  */
     245                 :            : static inline int list_is_first(const struct list_head *list,
     246                 :            :                                         const struct list_head *head)
     247                 :            : {
     248                 :          0 :         return list->prev == head;
     249                 :            : }
     250                 :            : 
     251                 :            : /**
     252                 :            :  * list_is_last - tests whether @list is the last entry in list @head
     253                 :            :  * @list: the entry to test
     254                 :            :  * @head: the head of the list
     255                 :            :  */
     256                 :            : static inline int list_is_last(const struct list_head *list,
     257                 :            :                                 const struct list_head *head)
     258                 :            : {
     259                 :          0 :         return list->next == head;
     260                 :            : }
     261                 :            : 
     262                 :            : /**
     263                 :            :  * list_empty - tests whether a list is empty
     264                 :            :  * @head: the list to test.
     265                 :            :  */
     266                 :       5129 : static inline int list_empty(const struct list_head *head)
     267                 :            : {
     268                 :  200063059 :         return READ_ONCE(head->next) == head;
     269                 :            : }
     270                 :            : 
     271                 :            : /**
     272                 :            :  * list_empty_careful - tests whether a list is empty and not being modified
     273                 :            :  * @head: the list to test
     274                 :            :  *
     275                 :            :  * Description:
     276                 :            :  * tests whether a list is empty _and_ checks that no other CPU might be
     277                 :            :  * in the process of modifying either member (next or prev)
     278                 :            :  *
     279                 :            :  * NOTE: using list_empty_careful() without synchronization
     280                 :            :  * can only be safe if the only activity that can happen
     281                 :            :  * to the list entry is list_del_init(). Eg. it cannot be used
     282                 :            :  * if another CPU could re-list_add() it.
     283                 :            :  */
     284                 :            : static inline int list_empty_careful(const struct list_head *head)
     285                 :            : {
     286                 :   18558780 :         struct list_head *next = head->next;
     287   [ +  +  +  +  :   18558780 :         return (next == head) && (next == head->prev);
          +  +  +  +  +  
          +  +  +  +  +  
          -  +  +  +  -  
          +  #  #  #  #  
             #  #  #  # ]
     288                 :            : }
     289                 :            : 
     290                 :            : /**
     291                 :            :  * list_rotate_left - rotate the list to the left
     292                 :            :  * @head: the head of the list
     293                 :            :  */
     294                 :            : static inline void list_rotate_left(struct list_head *head)
     295                 :            : {
     296                 :            :         struct list_head *first;
     297                 :            : 
     298                 :            :         if (!list_empty(head)) {
     299                 :            :                 first = head->next;
     300                 :            :                 list_move_tail(first, head);
     301                 :            :         }
     302                 :            : }
     303                 :            : 
     304                 :            : /**
     305                 :            :  * list_rotate_to_front() - Rotate list to specific item.
     306                 :            :  * @list: The desired new front of the list.
     307                 :            :  * @head: The head of the list.
     308                 :            :  *
     309                 :            :  * Rotates list so that @list becomes the new front of the list.
     310                 :            :  */
     311                 :            : static inline void list_rotate_to_front(struct list_head *list,
     312                 :            :                                         struct list_head *head)
     313                 :            : {
     314                 :            :         /*
     315                 :            :          * Deletes the list head from the list denoted by @head and
     316                 :            :          * places it as the tail of @list, this effectively rotates the
     317                 :            :          * list so that @list is at the front.
     318                 :            :          */
     319                 :            :         list_move_tail(head, list);
     320                 :            : }
     321                 :            : 
     322                 :            : /**
     323                 :            :  * list_is_singular - tests whether a list has just one entry.
     324                 :            :  * @head: the list to test.
     325                 :            :  */
     326                 :            : static inline int list_is_singular(const struct list_head *head)
     327                 :            : {
     328   [ +  -  +  +  :    2265843 :         return !list_empty(head) && (head->next == head->prev);
          +  +  +  +  +  
                +  +  + ]
     329                 :            : }
     330                 :            : 
     331                 :            : static inline void __list_cut_position(struct list_head *list,
     332                 :            :                 struct list_head *head, struct list_head *entry)
     333                 :            : {
     334                 :       1075 :         struct list_head *new_first = entry->next;
     335                 :       1075 :         list->next = head->next;
     336                 :       1075 :         list->next->prev = list;
     337                 :       1075 :         list->prev = entry;
     338                 :       1075 :         entry->next = list;
     339                 :       1075 :         head->next = new_first;
     340                 :       1075 :         new_first->prev = head;
     341                 :            : }
     342                 :            : 
     343                 :            : /**
     344                 :            :  * list_cut_position - cut a list into two
     345                 :            :  * @list: a new list to add all removed entries
     346                 :            :  * @head: a list with entries
     347                 :            :  * @entry: an entry within head, could be the head itself
     348                 :            :  *      and if so we won't cut the list
     349                 :            :  *
     350                 :            :  * This helper moves the initial part of @head, up to and
     351                 :            :  * including @entry, from @head to @list. You should
     352                 :            :  * pass on @entry an element you know is on @head. @list
     353                 :            :  * should be an empty list or a list you do not care about
     354                 :            :  * losing its data.
     355                 :            :  *
     356                 :            :  */
     357                 :       1075 : static inline void list_cut_position(struct list_head *list,
     358                 :            :                 struct list_head *head, struct list_head *entry)
     359                 :            : {
     360         [ +  - ]:       1075 :         if (list_empty(head))
     361                 :            :                 return;
     362   [ +  +  -  + ]:       1701 :         if (list_is_singular(head) &&
     363         [ #  # ]:        626 :                 (head->next != entry && head != entry))
     364                 :            :                 return;
     365         [ -  + ]:       1075 :         if (entry == head)
     366                 :            :                 INIT_LIST_HEAD(list);
     367                 :            :         else
     368                 :            :                 __list_cut_position(list, head, entry);
     369                 :            : }
     370                 :            : 
     371                 :            : /**
     372                 :            :  * list_cut_before - cut a list into two, before given entry
     373                 :            :  * @list: a new list to add all removed entries
     374                 :            :  * @head: a list with entries
     375                 :            :  * @entry: an entry within head, could be the head itself
     376                 :            :  *
     377                 :            :  * This helper moves the initial part of @head, up to but
     378                 :            :  * excluding @entry, from @head to @list.  You should pass
     379                 :            :  * in @entry an element you know is on @head.  @list should
     380                 :            :  * be an empty list or a list you do not care about losing
     381                 :            :  * its data.
     382                 :            :  * If @entry == @head, all entries on @head are moved to
     383                 :            :  * @list.
     384                 :            :  */
     385                 :            : static inline void list_cut_before(struct list_head *list,
     386                 :            :                                    struct list_head *head,
     387                 :            :                                    struct list_head *entry)
     388                 :            : {
     389         [ #  # ]:          0 :         if (head->next == entry) {
     390                 :            :                 INIT_LIST_HEAD(list);
     391                 :            :                 return;
     392                 :            :         }
     393                 :          0 :         list->next = head->next;
     394                 :          0 :         list->next->prev = list;
     395                 :          0 :         list->prev = entry->prev;
     396                 :          0 :         list->prev->next = list;
     397                 :          0 :         head->next = entry;
     398                 :          0 :         entry->prev = head;
     399                 :            : }
     400                 :            : 
     401                 :            : static inline void __list_splice(const struct list_head *list,
     402                 :            :                                  struct list_head *prev,
     403                 :            :                                  struct list_head *next)
     404                 :            : {
     405                 :    5042596 :         struct list_head *first = list->next;
     406                 :    5056693 :         struct list_head *last = list->prev;
     407                 :            : 
     408                 :    5056693 :         first->prev = prev;
     409                 :    5056693 :         prev->next = first;
     410                 :            : 
     411                 :    5056693 :         last->next = next;
     412                 :    5056693 :         next->prev = last;
     413                 :            : }
     414                 :            : 
     415                 :            : /**
     416                 :            :  * list_splice - join two lists, this is designed for stacks
     417                 :            :  * @list: the new list to add.
     418                 :            :  * @head: the place to add it in the first list.
     419                 :            :  */
     420                 :            : static inline void list_splice(const struct list_head *list,
     421                 :            :                                 struct list_head *head)
     422                 :            : {
     423   [ +  +  #  #  :    2084963 :         if (!list_empty(list))
          #  #  -  +  -  
                      + ]
     424                 :      22758 :                 __list_splice(list, head, head->next);
     425                 :            : }
     426                 :            : 
     427                 :            : /**
     428                 :            :  * list_splice_tail - join two lists, each list being a queue
     429                 :            :  * @list: the new list to add.
     430                 :            :  * @head: the place to add it in the first list.
     431                 :            :  */
     432                 :            : static inline void list_splice_tail(struct list_head *list,
     433                 :            :                                 struct list_head *head)
     434                 :            : {
     435   [ -  +  #  # ]:        836 :         if (!list_empty(list))
     436                 :          0 :                 __list_splice(list, head->prev, head);
     437                 :            : }
     438                 :            : 
     439                 :            : /**
     440                 :            :  * list_splice_init - join two lists and reinitialise the emptied list.
     441                 :            :  * @list: the new list to add.
     442                 :            :  * @head: the place to add it in the first list.
     443                 :            :  *
     444                 :            :  * The list at @list is reinitialised
     445                 :            :  */
     446                 :            : static inline void list_splice_init(struct list_head *list,
     447                 :            :                                     struct list_head *head)
     448                 :            : {
     449   [ +  +  +  +  :    2876906 :         if (!list_empty(list)) {
          #  #  #  #  #  
             #  #  #  #  
                      # ]
     450                 :    2091567 :                 __list_splice(list, head, head->next);
     451                 :            :                 INIT_LIST_HEAD(list);
     452                 :            :         }
     453                 :            : }
     454                 :            : 
     455                 :            : /**
     456                 :            :  * list_splice_tail_init - join two lists and reinitialise the emptied list
     457                 :            :  * @list: the new list to add.
     458                 :            :  * @head: the place to add it in the first list.
     459                 :            :  *
     460                 :            :  * Each of the lists is a queue.
     461                 :            :  * The list at @list is reinitialised
     462                 :            :  */
     463                 :            : static inline void list_splice_tail_init(struct list_head *list,
     464                 :            :                                          struct list_head *head)
     465                 :            : {
     466   [ +  +  +  +  :    2431101 :         if (!list_empty(list)) {
          +  +  -  +  -  
                      + ]
     467                 :    2252742 :                 __list_splice(list, head->prev, head);
     468                 :            :                 INIT_LIST_HEAD(list);
     469                 :            :         }
     470                 :            : }
     471                 :            : 
     472                 :            : /**
     473                 :            :  * list_entry - get the struct for this entry
     474                 :            :  * @ptr:        the &struct list_head pointer.
     475                 :            :  * @type:       the type of the struct this is embedded in.
     476                 :            :  * @member:     the name of the list_head within the struct.
     477                 :            :  */
     478                 :            : #define list_entry(ptr, type, member) \
     479                 :            :         container_of(ptr, type, member)
     480                 :            : 
     481                 :            : /**
     482                 :            :  * list_first_entry - get the first element from a list
     483                 :            :  * @ptr:        the list head to take the element from.
     484                 :            :  * @type:       the type of the struct this is embedded in.
     485                 :            :  * @member:     the name of the list_head within the struct.
     486                 :            :  *
     487                 :            :  * Note, that list is expected to be not empty.
     488                 :            :  */
     489                 :            : #define list_first_entry(ptr, type, member) \
     490                 :            :         list_entry((ptr)->next, type, member)
     491                 :            : 
     492                 :            : /**
     493                 :            :  * list_last_entry - get the last element from a list
     494                 :            :  * @ptr:        the list head to take the element from.
     495                 :            :  * @type:       the type of the struct this is embedded in.
     496                 :            :  * @member:     the name of the list_head within the struct.
     497                 :            :  *
     498                 :            :  * Note, that list is expected to be not empty.
     499                 :            :  */
     500                 :            : #define list_last_entry(ptr, type, member) \
     501                 :            :         list_entry((ptr)->prev, type, member)
     502                 :            : 
     503                 :            : /**
     504                 :            :  * list_first_entry_or_null - get the first element from a list
     505                 :            :  * @ptr:        the list head to take the element from.
     506                 :            :  * @type:       the type of the struct this is embedded in.
     507                 :            :  * @member:     the name of the list_head within the struct.
     508                 :            :  *
     509                 :            :  * Note that if the list is empty, it returns NULL.
     510                 :            :  */
     511                 :            : #define list_first_entry_or_null(ptr, type, member) ({ \
     512                 :            :         struct list_head *head__ = (ptr); \
     513                 :            :         struct list_head *pos__ = READ_ONCE(head__->next); \
     514                 :            :         pos__ != head__ ? list_entry(pos__, type, member) : NULL; \
     515                 :            : })
     516                 :            : 
     517                 :            : /**
     518                 :            :  * list_next_entry - get the next element in list
     519                 :            :  * @pos:        the type * to cursor
     520                 :            :  * @member:     the name of the list_head within the struct.
     521                 :            :  */
     522                 :            : #define list_next_entry(pos, member) \
     523                 :            :         list_entry((pos)->member.next, typeof(*(pos)), member)
     524                 :            : 
     525                 :            : /**
     526                 :            :  * list_prev_entry - get the prev element in list
     527                 :            :  * @pos:        the type * to cursor
     528                 :            :  * @member:     the name of the list_head within the struct.
     529                 :            :  */
     530                 :            : #define list_prev_entry(pos, member) \
     531                 :            :         list_entry((pos)->member.prev, typeof(*(pos)), member)
     532                 :            : 
     533                 :            : /**
     534                 :            :  * list_for_each        -       iterate over a list
     535                 :            :  * @pos:        the &struct list_head to use as a loop cursor.
     536                 :            :  * @head:       the head for your list.
     537                 :            :  */
     538                 :            : #define list_for_each(pos, head) \
     539                 :            :         for (pos = (head)->next; pos != (head); pos = pos->next)
     540                 :            : 
     541                 :            : /**
     542                 :            :  * list_for_each_prev   -       iterate over a list backwards
     543                 :            :  * @pos:        the &struct list_head to use as a loop cursor.
     544                 :            :  * @head:       the head for your list.
     545                 :            :  */
     546                 :            : #define list_for_each_prev(pos, head) \
     547                 :            :         for (pos = (head)->prev; pos != (head); pos = pos->prev)
     548                 :            : 
     549                 :            : /**
     550                 :            :  * list_for_each_safe - iterate over a list safe against removal of list entry
     551                 :            :  * @pos:        the &struct list_head to use as a loop cursor.
     552                 :            :  * @n:          another &struct list_head to use as temporary storage
     553                 :            :  * @head:       the head for your list.
     554                 :            :  */
     555                 :            : #define list_for_each_safe(pos, n, head) \
     556                 :            :         for (pos = (head)->next, n = pos->next; pos != (head); \
     557                 :            :                 pos = n, n = pos->next)
     558                 :            : 
     559                 :            : /**
     560                 :            :  * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
     561                 :            :  * @pos:        the &struct list_head to use as a loop cursor.
     562                 :            :  * @n:          another &struct list_head to use as temporary storage
     563                 :            :  * @head:       the head for your list.
     564                 :            :  */
     565                 :            : #define list_for_each_prev_safe(pos, n, head) \
     566                 :            :         for (pos = (head)->prev, n = pos->prev; \
     567                 :            :              pos != (head); \
     568                 :            :              pos = n, n = pos->prev)
     569                 :            : 
     570                 :            : /**
     571                 :            :  * list_for_each_entry  -       iterate over list of given type
     572                 :            :  * @pos:        the type * to use as a loop cursor.
     573                 :            :  * @head:       the head for your list.
     574                 :            :  * @member:     the name of the list_head within the struct.
     575                 :            :  */
     576                 :            : #define list_for_each_entry(pos, head, member)                          \
     577                 :            :         for (pos = list_first_entry(head, typeof(*pos), member);        \
     578                 :            :              &pos->member != (head);                                     \
     579                 :            :              pos = list_next_entry(pos, member))
     580                 :            : 
     581                 :            : /**
     582                 :            :  * list_for_each_entry_reverse - iterate backwards over list of given type.
     583                 :            :  * @pos:        the type * to use as a loop cursor.
     584                 :            :  * @head:       the head for your list.
     585                 :            :  * @member:     the name of the list_head within the struct.
     586                 :            :  */
     587                 :            : #define list_for_each_entry_reverse(pos, head, member)                  \
     588                 :            :         for (pos = list_last_entry(head, typeof(*pos), member);         \
     589                 :            :              &pos->member != (head);                                     \
     590                 :            :              pos = list_prev_entry(pos, member))
     591                 :            : 
     592                 :            : /**
     593                 :            :  * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
     594                 :            :  * @pos:        the type * to use as a start point
     595                 :            :  * @head:       the head of the list
     596                 :            :  * @member:     the name of the list_head within the struct.
     597                 :            :  *
     598                 :            :  * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
     599                 :            :  */
     600                 :            : #define list_prepare_entry(pos, head, member) \
     601                 :            :         ((pos) ? : list_entry(head, typeof(*pos), member))
     602                 :            : 
     603                 :            : /**
     604                 :            :  * list_for_each_entry_continue - continue iteration over list of given type
     605                 :            :  * @pos:        the type * to use as a loop cursor.
     606                 :            :  * @head:       the head for your list.
     607                 :            :  * @member:     the name of the list_head within the struct.
     608                 :            :  *
     609                 :            :  * Continue to iterate over list of given type, continuing after
     610                 :            :  * the current position.
     611                 :            :  */
     612                 :            : #define list_for_each_entry_continue(pos, head, member)                 \
     613                 :            :         for (pos = list_next_entry(pos, member);                        \
     614                 :            :              &pos->member != (head);                                     \
     615                 :            :              pos = list_next_entry(pos, member))
     616                 :            : 
     617                 :            : /**
     618                 :            :  * list_for_each_entry_continue_reverse - iterate backwards from the given point
     619                 :            :  * @pos:        the type * to use as a loop cursor.
     620                 :            :  * @head:       the head for your list.
     621                 :            :  * @member:     the name of the list_head within the struct.
     622                 :            :  *
     623                 :            :  * Start to iterate over list of given type backwards, continuing after
     624                 :            :  * the current position.
     625                 :            :  */
     626                 :            : #define list_for_each_entry_continue_reverse(pos, head, member)         \
     627                 :            :         for (pos = list_prev_entry(pos, member);                        \
     628                 :            :              &pos->member != (head);                                     \
     629                 :            :              pos = list_prev_entry(pos, member))
     630                 :            : 
     631                 :            : /**
     632                 :            :  * list_for_each_entry_from - iterate over list of given type from the current point
     633                 :            :  * @pos:        the type * to use as a loop cursor.
     634                 :            :  * @head:       the head for your list.
     635                 :            :  * @member:     the name of the list_head within the struct.
     636                 :            :  *
     637                 :            :  * Iterate over list of given type, continuing from current position.
     638                 :            :  */
     639                 :            : #define list_for_each_entry_from(pos, head, member)                     \
     640                 :            :         for (; &pos->member != (head);                                   \
     641                 :            :              pos = list_next_entry(pos, member))
     642                 :            : 
     643                 :            : /**
     644                 :            :  * list_for_each_entry_from_reverse - iterate backwards over list of given type
     645                 :            :  *                                    from the current point
     646                 :            :  * @pos:        the type * to use as a loop cursor.
     647                 :            :  * @head:       the head for your list.
     648                 :            :  * @member:     the name of the list_head within the struct.
     649                 :            :  *
     650                 :            :  * Iterate backwards over list of given type, continuing from current position.
     651                 :            :  */
     652                 :            : #define list_for_each_entry_from_reverse(pos, head, member)             \
     653                 :            :         for (; &pos->member != (head);                                   \
     654                 :            :              pos = list_prev_entry(pos, member))
     655                 :            : 
     656                 :            : /**
     657                 :            :  * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
     658                 :            :  * @pos:        the type * to use as a loop cursor.
     659                 :            :  * @n:          another type * to use as temporary storage
     660                 :            :  * @head:       the head for your list.
     661                 :            :  * @member:     the name of the list_head within the struct.
     662                 :            :  */
     663                 :            : #define list_for_each_entry_safe(pos, n, head, member)                  \
     664                 :            :         for (pos = list_first_entry(head, typeof(*pos), member),        \
     665                 :            :                 n = list_next_entry(pos, member);                       \
     666                 :            :              &pos->member != (head);                                     \
     667                 :            :              pos = n, n = list_next_entry(n, member))
     668                 :            : 
     669                 :            : /**
     670                 :            :  * list_for_each_entry_safe_continue - continue list iteration safe against removal
     671                 :            :  * @pos:        the type * to use as a loop cursor.
     672                 :            :  * @n:          another type * to use as temporary storage
     673                 :            :  * @head:       the head for your list.
     674                 :            :  * @member:     the name of the list_head within the struct.
     675                 :            :  *
     676                 :            :  * Iterate over list of given type, continuing after current point,
     677                 :            :  * safe against removal of list entry.
     678                 :            :  */
     679                 :            : #define list_for_each_entry_safe_continue(pos, n, head, member)                 \
     680                 :            :         for (pos = list_next_entry(pos, member),                                \
     681                 :            :                 n = list_next_entry(pos, member);                               \
     682                 :            :              &pos->member != (head);                                             \
     683                 :            :              pos = n, n = list_next_entry(n, member))
     684                 :            : 
     685                 :            : /**
     686                 :            :  * list_for_each_entry_safe_from - iterate over list from current point safe against removal
     687                 :            :  * @pos:        the type * to use as a loop cursor.
     688                 :            :  * @n:          another type * to use as temporary storage
     689                 :            :  * @head:       the head for your list.
     690                 :            :  * @member:     the name of the list_head within the struct.
     691                 :            :  *
     692                 :            :  * Iterate over list of given type from current point, safe against
     693                 :            :  * removal of list entry.
     694                 :            :  */
     695                 :            : #define list_for_each_entry_safe_from(pos, n, head, member)                     \
     696                 :            :         for (n = list_next_entry(pos, member);                                  \
     697                 :            :              &pos->member != (head);                                             \
     698                 :            :              pos = n, n = list_next_entry(n, member))
     699                 :            : 
     700                 :            : /**
     701                 :            :  * list_for_each_entry_safe_reverse - iterate backwards over list safe against removal
     702                 :            :  * @pos:        the type * to use as a loop cursor.
     703                 :            :  * @n:          another type * to use as temporary storage
     704                 :            :  * @head:       the head for your list.
     705                 :            :  * @member:     the name of the list_head within the struct.
     706                 :            :  *
     707                 :            :  * Iterate backwards over list of given type, safe against removal
     708                 :            :  * of list entry.
     709                 :            :  */
     710                 :            : #define list_for_each_entry_safe_reverse(pos, n, head, member)          \
     711                 :            :         for (pos = list_last_entry(head, typeof(*pos), member),         \
     712                 :            :                 n = list_prev_entry(pos, member);                       \
     713                 :            :              &pos->member != (head);                                     \
     714                 :            :              pos = n, n = list_prev_entry(n, member))
     715                 :            : 
     716                 :            : /**
     717                 :            :  * list_safe_reset_next - reset a stale list_for_each_entry_safe loop
     718                 :            :  * @pos:        the loop cursor used in the list_for_each_entry_safe loop
     719                 :            :  * @n:          temporary storage used in list_for_each_entry_safe
     720                 :            :  * @member:     the name of the list_head within the struct.
     721                 :            :  *
     722                 :            :  * list_safe_reset_next is not safe to use in general if the list may be
     723                 :            :  * modified concurrently (eg. the lock is dropped in the loop body). An
     724                 :            :  * exception to this is if the cursor element (pos) is pinned in the list,
     725                 :            :  * and list_safe_reset_next is called after re-taking the lock and before
     726                 :            :  * completing the current iteration of the loop body.
     727                 :            :  */
     728                 :            : #define list_safe_reset_next(pos, n, member)                            \
     729                 :            :         n = list_next_entry(pos, member)
     730                 :            : 
     731                 :            : /*
     732                 :            :  * Double linked lists with a single pointer list head.
     733                 :            :  * Mostly useful for hash tables where the two pointer list head is
     734                 :            :  * too wasteful.
     735                 :            :  * You lose the ability to access the tail in O(1).
     736                 :            :  */
     737                 :            : 
     738                 :            : #define HLIST_HEAD_INIT { .first = NULL }
     739                 :            : #define HLIST_HEAD(name) struct hlist_head name = {  .first = NULL }
     740                 :            : #define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
     741                 :            : static inline void INIT_HLIST_NODE(struct hlist_node *h)
     742                 :            : {
     743                 :   34191158 :         h->next = NULL;
     744                 :   34191158 :         h->pprev = NULL;
     745                 :            : }
     746                 :            : 
     747                 :          0 : static inline int hlist_unhashed(const struct hlist_node *h)
     748                 :            : {
     749                 :   18901663 :         return !h->pprev;
     750                 :            : }
     751                 :            : 
     752                 :            : static inline int hlist_empty(const struct hlist_head *h)
     753                 :            : {
     754   [ #  #  #  # ]:    3950918 :         return !READ_ONCE(h->first);
     755                 :            : }
     756                 :            : 
     757                 :            : static inline void __hlist_del(struct hlist_node *n)
     758                 :            : {
     759                 :    9273170 :         struct hlist_node *next = n->next;
     760                 :    2655592 :         struct hlist_node **pprev = n->pprev;
     761                 :            : 
     762                 :    9277359 :         WRITE_ONCE(*pprev, next);
     763   [ +  +  +  +  :    9277359 :         if (next)
          +  +  #  #  #  
          #  +  +  +  +  
          +  +  #  #  #  
                      # ]
     764                 :     526362 :                 next->pprev = pprev;
     765                 :            : }
     766                 :            : 
     767                 :            : static inline void hlist_del(struct hlist_node *n)
     768                 :            : {
     769                 :            :         __hlist_del(n);
     770                 :      11980 :         n->next = LIST_POISON1;
     771                 :      11980 :         n->pprev = LIST_POISON2;
     772                 :            : }
     773                 :            : 
     774                 :            : static inline void hlist_del_init(struct hlist_node *n)
     775                 :            : {
     776   [ +  +  +  -  :    6455010 :         if (!hlist_unhashed(n)) {
                   +  + ]
     777                 :            :                 __hlist_del(n);
     778                 :            :                 INIT_HLIST_NODE(n);
     779                 :            :         }
     780                 :            : }
     781                 :            : 
     782                 :            : static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
     783                 :            : {
     784                 :   14656580 :         struct hlist_node *first = h->first;
     785                 :   14659064 :         n->next = first;
     786   [ +  +  +  +  :   14657615 :         if (first)
          +  +  +  +  +  
             +  #  #  #  
                      # ]
     787                 :     541337 :                 first->pprev = &n->next;
     788                 :   14658857 :         WRITE_ONCE(h->first, n);
     789                 :   14659064 :         n->pprev = &h->first;
     790                 :            : }
     791                 :            : 
     792                 :            : /* next must be != NULL */
     793                 :            : static inline void hlist_add_before(struct hlist_node *n,
     794                 :            :                                         struct hlist_node *next)
     795                 :            : {
     796                 :            :         n->pprev = next->pprev;
     797                 :            :         n->next = next;
     798                 :            :         next->pprev = &n->next;
     799                 :            :         WRITE_ONCE(*(n->pprev), n);
     800                 :            : }
     801                 :            : 
     802                 :            : static inline void hlist_add_behind(struct hlist_node *n,
     803                 :            :                                     struct hlist_node *prev)
     804                 :            : {
     805                 :            :         n->next = prev->next;
     806                 :            :         prev->next = n;
     807                 :            :         n->pprev = &prev->next;
     808                 :            : 
     809                 :            :         if (n->next)
     810                 :            :                 n->next->pprev  = &n->next;
     811                 :            : }
     812                 :            : 
     813                 :            : /* after that we'll appear to be on some hlist and hlist_del will work */
     814                 :            : static inline void hlist_add_fake(struct hlist_node *n)
     815                 :            : {
     816                 :            :         n->pprev = &n->next;
     817                 :            : }
     818                 :            : 
     819                 :            : static inline bool hlist_fake(struct hlist_node *h)
     820                 :            : {
     821                 :     215871 :         return h->pprev == &h->next;
     822                 :            : }
     823                 :            : 
     824                 :            : /*
     825                 :            :  * Check whether the node is the only node of the head without
     826                 :            :  * accessing head:
     827                 :            :  */
     828                 :            : static inline bool
     829                 :            : hlist_is_singular_node(struct hlist_node *n, struct hlist_head *h)
     830                 :            : {
     831   [ +  +  +  + ]:    1413291 :         return !n->next && n->pprev == &h->first;
     832                 :            : }
     833                 :            : 
     834                 :            : /*
     835                 :            :  * Move a list from one list head to another. Fixup the pprev
     836                 :            :  * reference of the first entry if it exists.
     837                 :            :  */
     838                 :            : static inline void hlist_move_list(struct hlist_head *old,
     839                 :            :                                    struct hlist_head *new)
     840                 :            : {
     841                 :     550656 :         new->first = old->first;
     842         [ +  + ]:     550656 :         if (new->first)
     843                 :     535856 :                 new->first->pprev = &new->first;
     844                 :     550656 :         old->first = NULL;
     845                 :            : }
     846                 :            : 
     847                 :            : #define hlist_entry(ptr, type, member) container_of(ptr,type,member)
     848                 :            : 
     849                 :            : #define hlist_for_each(pos, head) \
     850                 :            :         for (pos = (head)->first; pos ; pos = pos->next)
     851                 :            : 
     852                 :            : #define hlist_for_each_safe(pos, n, head) \
     853                 :            :         for (pos = (head)->first; pos && ({ n = pos->next; 1; }); \
     854                 :            :              pos = n)
     855                 :            : 
     856                 :            : #define hlist_entry_safe(ptr, type, member) \
     857                 :            :         ({ typeof(ptr) ____ptr = (ptr); \
     858                 :            :            ____ptr ? hlist_entry(____ptr, type, member) : NULL; \
     859                 :            :         })
     860                 :            : 
     861                 :            : /**
     862                 :            :  * hlist_for_each_entry - iterate over list of given type
     863                 :            :  * @pos:        the type * to use as a loop cursor.
     864                 :            :  * @head:       the head for your list.
     865                 :            :  * @member:     the name of the hlist_node within the struct.
     866                 :            :  */
     867                 :            : #define hlist_for_each_entry(pos, head, member)                         \
     868                 :            :         for (pos = hlist_entry_safe((head)->first, typeof(*(pos)), member);\
     869                 :            :              pos;                                                       \
     870                 :            :              pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
     871                 :            : 
     872                 :            : /**
     873                 :            :  * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
     874                 :            :  * @pos:        the type * to use as a loop cursor.
     875                 :            :  * @member:     the name of the hlist_node within the struct.
     876                 :            :  */
     877                 :            : #define hlist_for_each_entry_continue(pos, member)                      \
     878                 :            :         for (pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member);\
     879                 :            :              pos;                                                       \
     880                 :            :              pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
     881                 :            : 
     882                 :            : /**
     883                 :            :  * hlist_for_each_entry_from - iterate over a hlist continuing from current point
     884                 :            :  * @pos:        the type * to use as a loop cursor.
     885                 :            :  * @member:     the name of the hlist_node within the struct.
     886                 :            :  */
     887                 :            : #define hlist_for_each_entry_from(pos, member)                          \
     888                 :            :         for (; pos;                                                     \
     889                 :            :              pos = hlist_entry_safe((pos)->member.next, typeof(*(pos)), member))
     890                 :            : 
     891                 :            : /**
     892                 :            :  * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
     893                 :            :  * @pos:        the type * to use as a loop cursor.
     894                 :            :  * @n:          another &struct hlist_node to use as temporary storage
     895                 :            :  * @head:       the head for your list.
     896                 :            :  * @member:     the name of the hlist_node within the struct.
     897                 :            :  */
     898                 :            : #define hlist_for_each_entry_safe(pos, n, head, member)                 \
     899                 :            :         for (pos = hlist_entry_safe((head)->first, typeof(*pos), member);\
     900                 :            :              pos && ({ n = pos->member.next; 1; });                  \
     901                 :            :              pos = hlist_entry_safe(n, typeof(*pos), member))
     902                 :            : 
     903                 :            : #endif

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