include/linux/freezer.h

   1 /* Freezer declarations */
   2
   3 #ifndef FREEZER_H_INCLUDED
   4 #define FREEZER_H_INCLUDED
   5
   6 #include <linux/sched.h>
   7 #include <linux/wait.h>
   8 #include <linux/atomic.h>
   9
  10 #ifdef CONFIG_FREEZER
  11 extern atomic_t system_freezing_cnt;    /* nr of freezing conds in effect */
  12 extern bool pm_freezing;                /* PM freezing in effect */
  13 extern bool pm_nosig_freezing;          /* PM nosig freezing in effect */
  14
  15 /*
  16  * Check if a process has been frozen
  17  */
  18 static inline bool frozen(struct task_struct *p)
  19 {
  20         return p->flags & PF_FROZEN;
  21 }
  22
  23 extern bool freezing_slow_path(struct task_struct *p);
  24
  25 /*
  26  * Check if there is a request to freeze a process
  27  */
  28 static inline bool freezing(struct task_struct *p)
  29 {
  30         if (likely(!atomic_read(&system_freezing_cnt)))
  31                 return false;
  32         return freezing_slow_path(p);
  33 }
  34
  35 /* Takes and releases task alloc lock using task_lock() */
  36 extern void __thaw_task(struct task_struct *t);
  37
  38 extern bool __refrigerator(bool check_kthr_stop);
  39 extern int freeze_processes(void);
  40 extern int freeze_kernel_threads(void);
  41 extern void thaw_processes(void);
  42
  43 static inline bool try_to_freeze(void)
  44 {
  45         might_sleep();
  46         if (likely(!freezing(current)))
  47                 return false;
  48         return __refrigerator(false);
  49 }
  50
  51 extern bool freeze_task(struct task_struct *p);
  52 extern bool set_freezable(void);
  53
  54 #ifdef CONFIG_CGROUP_FREEZER
  55 extern bool cgroup_freezing(struct task_struct *task);
  56 #else /* !CONFIG_CGROUP_FREEZER */
  57 static inline bool cgroup_freezing(struct task_struct *task)
  58 {
  59         return false;
  60 }
  61 #endif /* !CONFIG_CGROUP_FREEZER */
  62
  63 /*
  64  * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it
  65  * calls wait_for_completion(&vfork) and reset right after it returns from this
  66  * function.  Next, the parent should call try_to_freeze() to freeze itself
  67  * appropriately in case the child has exited before the freezing of tasks is
  68  * complete.  However, we don't want kernel threads to be frozen in unexpected
  69  * places, so we allow them to block freeze_processes() instead or to set
  70  * PF_NOFREEZE if needed and PF_FREEZER_SKIP is only set for userland vfork
  71  * parents.  Fortunately, in the ____call_usermodehelper() case the parent won't
  72  * really block freeze_processes(), since ____call_usermodehelper() (the child)
  73  * does a little before exec/exit and it can't be frozen before waking up the
  74  * parent.
  75  */
  76
  77 /*
  78  * If the current task is a user space one, tell the freezer not to count it as
  79  * freezable.
  80  */
  81 static inline void freezer_do_not_count(void)
  82 {
  83         if (current->mm)
  84                 current->flags |= PF_FREEZER_SKIP;
  85 }
  86
  87 /*
  88  * If the current task is a user space one, tell the freezer to count it as
  89  * freezable again and try to freeze it.
  90  */
  91 static inline void freezer_count(void)
  92 {
  93         if (current->mm) {
  94                 current->flags &= ~PF_FREEZER_SKIP;
  95                 try_to_freeze();
  96         }
  97 }
  98
  99 /*
 100  * Check if the task should be counted as freezable by the freezer
 101  */
 102 static inline int freezer_should_skip(struct task_struct *p)
 103 {
 104         return !!(p->flags & PF_FREEZER_SKIP);
 105 }
 106
 107 /*
 108  * Freezer-friendly wrappers around wait_event_interruptible(),
 109  * wait_event_killable() and wait_event_interruptible_timeout(), originally
 110  * defined in <linux/wait.h>
 111  */
 112
 113 #define wait_event_freezekillable(wq, condition)                        \
 114 ({                                                                      \
 115         int __retval;                                                   \
 116         freezer_do_not_count();                                         \
 117         __retval = wait_event_killable(wq, (condition));                \
 118         freezer_count();                                                \
 119         __retval;                                                       \
 120 })
 121
 122 #define wait_event_freezable(wq, condition)                             \
 123 ({                                                                      \
 124         int __retval;                                                   \
 125         for (;;) {                                                      \
 126                 __retval = wait_event_interruptible(wq,                 \
 127                                 (condition) || freezing(current));      \
 128                 if (__retval || (condition))                            \
 129                         break;                                          \
 130                 try_to_freeze();                                        \
 131         }                                                               \
 132         __retval;                                                       \
 133 })
 134
 135 #define wait_event_freezable_timeout(wq, condition, timeout)            \
 136 ({                                                                      \
 137         long __retval = timeout;                                        \
 138         for (;;) {                                                      \
 139                 __retval = wait_event_interruptible_timeout(wq,         \
 140                                 (condition) || freezing(current),       \
 141                                 __retval);                              \
 142                 if (__retval <= 0 || (condition))                       \
 143                         break;                                          \
 144                 try_to_freeze();                                        \
 145         }                                                               \
 146         __retval;                                                       \
 147 })
 148
 149 #else /* !CONFIG_FREEZER */
 150 static inline bool frozen(struct task_struct *p) { return false; }
 151 static inline bool freezing(struct task_struct *p) { return false; }
 152 static inline void __thaw_task(struct task_struct *t) {}
 153
 154 static inline bool __refrigerator(bool check_kthr_stop) { return false; }
 155 static inline int freeze_processes(void) { return -ENOSYS; }
 156 static inline int freeze_kernel_threads(void) { return -ENOSYS; }
 157 static inline void thaw_processes(void) {}
 158
 159 static inline bool try_to_freeze(void) { return false; }
 160
 161 static inline void freezer_do_not_count(void) {}
 162 static inline void freezer_count(void) {}
 163 static inline int freezer_should_skip(struct task_struct *p) { return 0; }
 164 static inline void set_freezable(void) {}
 165
 166 #define wait_event_freezable(wq, condition)                             \
 167                 wait_event_interruptible(wq, condition)
 168
 169 #define wait_event_freezable_timeout(wq, condition, timeout)            \
 170                 wait_event_interruptible_timeout(wq, condition, timeout)
 171
 172 #define wait_event_freezekillable(wq, condition)                \
 173                 wait_event_killable(wq, condition)
 174
 175 #endif /* !CONFIG_FREEZER */
 176
 177 #endif  /* FREEZER_H_INCLUDED */