LCOV - code coverage report
Current view: top level - include/linux - freezer.h (source / functions) Hit Total Coverage
Test: combined.info Lines: 19 59 32.2 %
Date: 2022-04-01 14:35:51 Functions: 3 8 37.5 %
Branches: 2 12 16.7 %

           Branch data     Line data    Source code
       1                 :            : /* SPDX-License-Identifier: GPL-2.0 */
       2                 :            : /* Freezer declarations */
       3                 :            : 
       4                 :            : #ifndef FREEZER_H_INCLUDED
       5                 :            : #define FREEZER_H_INCLUDED
       6                 :            : 
       7                 :            : #include <linux/debug_locks.h>
       8                 :            : #include <linux/sched.h>
       9                 :            : #include <linux/wait.h>
      10                 :            : #include <linux/atomic.h>
      11                 :            : 
      12                 :            : #ifdef CONFIG_FREEZER
      13                 :            : extern atomic_t system_freezing_cnt;    /* nr of freezing conds in effect */
      14                 :            : extern bool pm_freezing;                /* PM freezing in effect */
      15                 :            : extern bool pm_nosig_freezing;          /* PM nosig freezing in effect */
      16                 :            : 
      17                 :            : /*
      18                 :            :  * Timeout for stopping processes
      19                 :            :  */
      20                 :            : extern unsigned int freeze_timeout_msecs;
      21                 :            : 
      22                 :            : /*
      23                 :            :  * Check if a process has been frozen
      24                 :            :  */
      25                 :          0 : static inline bool frozen(struct task_struct *p)
      26                 :            : {
      27   [ #  #  #  # ]:          0 :         return p->flags & PF_FROZEN;
      28                 :            : }
      29                 :            : 
      30                 :            : extern bool freezing_slow_path(struct task_struct *p);
      31                 :            : 
      32                 :            : /*
      33                 :            :  * Check if there is a request to freeze a process
      34                 :            :  */
      35                 :     105316 : static inline bool freezing(struct task_struct *p)
      36                 :            : {
      37         [ -  + ]:     105316 :         if (likely(!atomic_read(&system_freezing_cnt)))
      38                 :            :                 return false;
      39                 :          0 :         return freezing_slow_path(p);
      40                 :            : }
      41                 :            : 
      42                 :            : /* Takes and releases task alloc lock using task_lock() */
      43                 :            : extern void __thaw_task(struct task_struct *t);
      44                 :            : 
      45                 :            : extern bool __refrigerator(bool check_kthr_stop);
      46                 :            : extern int freeze_processes(void);
      47                 :            : extern int freeze_kernel_threads(void);
      48                 :            : extern void thaw_processes(void);
      49                 :            : extern void thaw_kernel_threads(void);
      50                 :            : 
      51                 :            : /*
      52                 :            :  * DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION
      53                 :            :  * If try_to_freeze causes a lockdep warning it means the caller may deadlock
      54                 :            :  */
      55                 :      36718 : static inline bool try_to_freeze_unsafe(void)
      56                 :            : {
      57                 :      36718 :         might_sleep();
      58         [ -  + ]:      36718 :         if (likely(!freezing(current)))
      59                 :            :                 return false;
      60                 :          0 :         return __refrigerator(false);
      61                 :            : }
      62                 :            : 
      63                 :      36718 : static inline bool try_to_freeze(void)
      64                 :            : {
      65                 :      36718 :         if (!(current->flags & PF_NOFREEZE))
      66                 :            :                 debug_check_no_locks_held();
      67                 :      36718 :         return try_to_freeze_unsafe();
      68                 :            : }
      69                 :            : 
      70                 :            : extern bool freeze_task(struct task_struct *p);
      71                 :            : extern bool set_freezable(void);
      72                 :            : 
      73                 :            : #ifdef CONFIG_CGROUP_FREEZER
      74                 :            : extern bool cgroup_freezing(struct task_struct *task);
      75                 :            : #else /* !CONFIG_CGROUP_FREEZER */
      76                 :            : static inline bool cgroup_freezing(struct task_struct *task)
      77                 :            : {
      78                 :            :         return false;
      79                 :            : }
      80                 :            : #endif /* !CONFIG_CGROUP_FREEZER */
      81                 :            : 
      82                 :            : /*
      83                 :            :  * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it
      84                 :            :  * calls wait_for_completion(&vfork) and reset right after it returns from this
      85                 :            :  * function.  Next, the parent should call try_to_freeze() to freeze itself
      86                 :            :  * appropriately in case the child has exited before the freezing of tasks is
      87                 :            :  * complete.  However, we don't want kernel threads to be frozen in unexpected
      88                 :            :  * places, so we allow them to block freeze_processes() instead or to set
      89                 :            :  * PF_NOFREEZE if needed. Fortunately, in the ____call_usermodehelper() case the
      90                 :            :  * parent won't really block freeze_processes(), since ____call_usermodehelper()
      91                 :            :  * (the child) does a little before exec/exit and it can't be frozen before
      92                 :            :  * waking up the parent.
      93                 :            :  */
      94                 :            : 
      95                 :            : 
      96                 :            : /**
      97                 :            :  * freezer_do_not_count - tell freezer to ignore %current
      98                 :            :  *
      99                 :            :  * Tell freezers to ignore the current task when determining whether the
     100                 :            :  * target frozen state is reached.  IOW, the current task will be
     101                 :            :  * considered frozen enough by freezers.
     102                 :            :  *
     103                 :            :  * The caller shouldn't do anything which isn't allowed for a frozen task
     104                 :            :  * until freezer_cont() is called.  Usually, freezer[_do_not]_count() pair
     105                 :            :  * wrap a scheduling operation and nothing much else.
     106                 :            :  */
     107                 :       1109 : static inline void freezer_do_not_count(void)
     108                 :            : {
     109                 :       1109 :         current->flags |= PF_FREEZER_SKIP;
     110                 :            : }
     111                 :            : 
     112                 :            : /**
     113                 :            :  * freezer_count - tell freezer to stop ignoring %current
     114                 :            :  *
     115                 :            :  * Undo freezer_do_not_count().  It tells freezers that %current should be
     116                 :            :  * considered again and tries to freeze if freezing condition is already in
     117                 :            :  * effect.
     118                 :            :  */
     119                 :       1004 : static inline void freezer_count(void)
     120                 :            : {
     121                 :       1004 :         current->flags &= ~PF_FREEZER_SKIP;
     122                 :            :         /*
     123                 :            :          * If freezing is in progress, the following paired with smp_mb()
     124                 :            :          * in freezer_should_skip() ensures that either we see %true
     125                 :            :          * freezing() or freezer_should_skip() sees !PF_FREEZER_SKIP.
     126                 :            :          */
     127                 :       1004 :         smp_mb();
     128                 :       1004 :         try_to_freeze();
     129                 :            : }
     130                 :            : 
     131                 :            : /* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
     132                 :          0 : static inline void freezer_count_unsafe(void)
     133                 :            : {
     134                 :          0 :         current->flags &= ~PF_FREEZER_SKIP;
     135                 :          0 :         smp_mb();
     136                 :          0 :         try_to_freeze_unsafe();
     137                 :            : }
     138                 :            : 
     139                 :            : /**
     140                 :            :  * freezer_should_skip - whether to skip a task when determining frozen
     141                 :            :  *                       state is reached
     142                 :            :  * @p: task in quesion
     143                 :            :  *
     144                 :            :  * This function is used by freezers after establishing %true freezing() to
     145                 :            :  * test whether a task should be skipped when determining the target frozen
     146                 :            :  * state is reached.  IOW, if this function returns %true, @p is considered
     147                 :            :  * frozen enough.
     148                 :            :  */
     149                 :          0 : static inline bool freezer_should_skip(struct task_struct *p)
     150                 :            : {
     151                 :            :         /*
     152                 :            :          * The following smp_mb() paired with the one in freezer_count()
     153                 :            :          * ensures that either freezer_count() sees %true freezing() or we
     154                 :            :          * see cleared %PF_FREEZER_SKIP and return %false.  This makes it
     155                 :            :          * impossible for a task to slip frozen state testing after
     156                 :            :          * clearing %PF_FREEZER_SKIP.
     157                 :            :          */
     158                 :          0 :         smp_mb();
     159   [ #  #  #  # ]:          0 :         return p->flags & PF_FREEZER_SKIP;
     160                 :            : }
     161                 :            : 
     162                 :            : /*
     163                 :            :  * These functions are intended to be used whenever you want allow a sleeping
     164                 :            :  * task to be frozen. Note that neither return any clear indication of
     165                 :            :  * whether a freeze event happened while in this function.
     166                 :            :  */
     167                 :            : 
     168                 :            : /* Like schedule(), but should not block the freezer. */
     169                 :       1109 : static inline void freezable_schedule(void)
     170                 :            : {
     171                 :       1109 :         freezer_do_not_count();
     172                 :       1109 :         schedule();
     173                 :       1004 :         freezer_count();
     174                 :       1004 : }
     175                 :            : 
     176                 :            : /* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
     177                 :          0 : static inline void freezable_schedule_unsafe(void)
     178                 :            : {
     179                 :          0 :         freezer_do_not_count();
     180                 :          0 :         schedule();
     181                 :          0 :         freezer_count_unsafe();
     182                 :          0 : }
     183                 :            : 
     184                 :            : /*
     185                 :            :  * Like schedule_timeout(), but should not block the freezer.  Do not
     186                 :            :  * call this with locks held.
     187                 :            :  */
     188                 :          0 : static inline long freezable_schedule_timeout(long timeout)
     189                 :            : {
     190                 :          0 :         long __retval;
     191                 :          0 :         freezer_do_not_count();
     192                 :          0 :         __retval = schedule_timeout(timeout);
     193                 :          0 :         freezer_count();
     194                 :          0 :         return __retval;
     195                 :            : }
     196                 :            : 
     197                 :            : /*
     198                 :            :  * Like schedule_timeout_interruptible(), but should not block the freezer.  Do not
     199                 :            :  * call this with locks held.
     200                 :            :  */
     201                 :          0 : static inline long freezable_schedule_timeout_interruptible(long timeout)
     202                 :            : {
     203                 :          0 :         long __retval;
     204                 :          0 :         freezer_do_not_count();
     205                 :          0 :         __retval = schedule_timeout_interruptible(timeout);
     206                 :          0 :         freezer_count();
     207                 :          0 :         return __retval;
     208                 :            : }
     209                 :            : 
     210                 :            : /* Like schedule_timeout_killable(), but should not block the freezer. */
     211                 :            : static inline long freezable_schedule_timeout_killable(long timeout)
     212                 :            : {
     213                 :            :         long __retval;
     214                 :            :         freezer_do_not_count();
     215                 :            :         __retval = schedule_timeout_killable(timeout);
     216                 :            :         freezer_count();
     217                 :            :         return __retval;
     218                 :            : }
     219                 :            : 
     220                 :            : /* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
     221                 :          0 : static inline long freezable_schedule_timeout_killable_unsafe(long timeout)
     222                 :            : {
     223                 :          0 :         long __retval;
     224                 :          0 :         freezer_do_not_count();
     225                 :          0 :         __retval = schedule_timeout_killable(timeout);
     226                 :          0 :         freezer_count_unsafe();
     227                 :          0 :         return __retval;
     228                 :            : }
     229                 :            : 
     230                 :            : /*
     231                 :            :  * Like schedule_hrtimeout_range(), but should not block the freezer.  Do not
     232                 :            :  * call this with locks held.
     233                 :            :  */
     234                 :          0 : static inline int freezable_schedule_hrtimeout_range(ktime_t *expires,
     235                 :            :                 u64 delta, const enum hrtimer_mode mode)
     236                 :            : {
     237                 :          0 :         int __retval;
     238                 :          0 :         freezer_do_not_count();
     239                 :          0 :         __retval = schedule_hrtimeout_range(expires, delta, mode);
     240                 :          0 :         freezer_count();
     241                 :          0 :         return __retval;
     242                 :            : }
     243                 :            : 
     244                 :            : /*
     245                 :            :  * Freezer-friendly wrappers around wait_event_interruptible(),
     246                 :            :  * wait_event_killable() and wait_event_interruptible_timeout(), originally
     247                 :            :  * defined in <linux/wait.h>
     248                 :            :  */
     249                 :            : 
     250                 :            : /* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
     251                 :            : #define wait_event_freezekillable_unsafe(wq, condition)                 \
     252                 :            : ({                                                                      \
     253                 :            :         int __retval;                                                   \
     254                 :            :         freezer_do_not_count();                                         \
     255                 :            :         __retval = wait_event_killable(wq, (condition));                \
     256                 :            :         freezer_count_unsafe();                                         \
     257                 :            :         __retval;                                                       \
     258                 :            : })
     259                 :            : 
     260                 :            : #else /* !CONFIG_FREEZER */
     261                 :            : static inline bool frozen(struct task_struct *p) { return false; }
     262                 :            : static inline bool freezing(struct task_struct *p) { return false; }
     263                 :            : static inline void __thaw_task(struct task_struct *t) {}
     264                 :            : 
     265                 :            : static inline bool __refrigerator(bool check_kthr_stop) { return false; }
     266                 :            : static inline int freeze_processes(void) { return -ENOSYS; }
     267                 :            : static inline int freeze_kernel_threads(void) { return -ENOSYS; }
     268                 :            : static inline void thaw_processes(void) {}
     269                 :            : static inline void thaw_kernel_threads(void) {}
     270                 :            : 
     271                 :            : static inline bool try_to_freeze_nowarn(void) { return false; }
     272                 :            : static inline bool try_to_freeze(void) { return false; }
     273                 :            : 
     274                 :            : static inline void freezer_do_not_count(void) {}
     275                 :            : static inline void freezer_count(void) {}
     276                 :            : static inline int freezer_should_skip(struct task_struct *p) { return 0; }
     277                 :            : static inline void set_freezable(void) {}
     278                 :            : 
     279                 :            : #define freezable_schedule()  schedule()
     280                 :            : 
     281                 :            : #define freezable_schedule_unsafe()  schedule()
     282                 :            : 
     283                 :            : #define freezable_schedule_timeout(timeout)  schedule_timeout(timeout)
     284                 :            : 
     285                 :            : #define freezable_schedule_timeout_interruptible(timeout)               \
     286                 :            :         schedule_timeout_interruptible(timeout)
     287                 :            : 
     288                 :            : #define freezable_schedule_timeout_killable(timeout)                    \
     289                 :            :         schedule_timeout_killable(timeout)
     290                 :            : 
     291                 :            : #define freezable_schedule_timeout_killable_unsafe(timeout)             \
     292                 :            :         schedule_timeout_killable(timeout)
     293                 :            : 
     294                 :            : #define freezable_schedule_hrtimeout_range(expires, delta, mode)        \
     295                 :            :         schedule_hrtimeout_range(expires, delta, mode)
     296                 :            : 
     297                 :            : #define wait_event_freezekillable_unsafe(wq, condition)                 \
     298                 :            :                 wait_event_killable(wq, condition)
     299                 :            : 
     300                 :            : #endif /* !CONFIG_FREEZER */
     301                 :            : 
     302                 :            : #endif  /* FREEZER_H_INCLUDED */

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