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 void thaw_processes(void);
  41
  42 static inline bool try_to_freeze(void)
  43 {
  44         might_sleep();
  45         if (likely(!freezing(current)))
  46                 return false;
  47         return __refrigerator(false);
  48 }
  49
  50 extern bool freeze_task(struct task_struct *p, bool sig_only);
  51 extern bool __set_freezable(bool with_signal);
  52
  53 #ifdef CONFIG_CGROUP_FREEZER
  54 extern bool cgroup_freezing(struct task_struct *task);
  55 #else /* !CONFIG_CGROUP_FREEZER */
  56 static inline bool cgroup_freezing(struct task_struct *task)
  57 {
  58         return false;
  59 }
  60 #endif /* !CONFIG_CGROUP_FREEZER */
  61
  62 /*
  63  * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it
  64  * calls wait_for_completion(&vfork) and reset right after it returns from this
  65  * function.  Next, the parent should call try_to_freeze() to freeze itself
  66  * appropriately in case the child has exited before the freezing of tasks is
  67  * complete.  However, we don't want kernel threads to be frozen in unexpected
  68  * places, so we allow them to block freeze_processes() instead or to set
  69  * PF_NOFREEZE if needed and PF_FREEZER_SKIP is only set for userland vfork
  70  * parents.  Fortunately, in the ____call_usermodehelper() case the parent won't
  71  * really block freeze_processes(), since ____call_usermodehelper() (the child)
  72  * does a little before exec/exit and it can't be frozen before waking up the
  73  * parent.
  74  */
  75
  76 /*
  77  * If the current task is a user space one, tell the freezer not to count it as
  78  * freezable.
  79  */
  80 static inline void freezer_do_not_count(void)
  81 {
  82         if (current->mm)
  83                 current->flags |= PF_FREEZER_SKIP;
  84 }
  85
  86 /*
  87  * If the current task is a user space one, tell the freezer to count it as
  88  * freezable again and try to freeze it.
  89  */
  90 static inline void freezer_count(void)
  91 {
  92         if (current->mm) {
  93                 current->flags &= ~PF_FREEZER_SKIP;
  94                 try_to_freeze();
  95         }
  96 }
  97
  98 /*
  99  * Check if the task should be counted as freezable by the freezer
 100  */
 101 static inline int freezer_should_skip(struct task_struct *p)
 102 {
 103         return !!(p->flags & PF_FREEZER_SKIP);
 104 }
 105
 106 /*
 107  * Tell the freezer that the current task should be frozen by it
 108  */
 109 static inline bool set_freezable(void)
 110 {
 111         return __set_freezable(false);
 112 }
 113
 114 /*
 115  * Tell the freezer that the current task should be frozen by it and that it
 116  * should send a fake signal to the task to freeze it.
 117  */
 118 static inline bool set_freezable_with_signal(void)
 119 {
 120         return __set_freezable(true);
 121 }
 122
 123 /*
 124  * Freezer-friendly wrappers around wait_event_interruptible() and
 125  * wait_event_interruptible_timeout(), originally defined in <linux/wait.h>
 126  */
 127
 128 #define wait_event_freezable(wq, condition)                             \
 129 ({                                                                      \
 130         int __retval;                                                   \
 131         do {                                                            \
 132                 __retval = wait_event_interruptible(wq,                 \
 133                                 (condition) || freezing(current));      \
 134                 if (__retval && !freezing(current))                     \
 135                         break;                                          \
 136                 else if (!(condition))                                  \
 137                         __retval = -ERESTARTSYS;                        \
 138         } while (try_to_freeze());                                      \
 139         __retval;                                                       \
 140 })
 141
 142
 143 #define wait_event_freezable_timeout(wq, condition, timeout)            \
 144 ({                                                                      \
 145         long __retval = timeout;                                        \
 146         do {                                                            \
 147                 __retval = wait_event_interruptible_timeout(wq,         \
 148                                 (condition) || freezing(current),       \
 149                                 __retval);                              \
 150         } while (try_to_freeze());                                      \
 151         __retval;                                                       \
 152 })
 153 #else /* !CONFIG_FREEZER */
 154 static inline bool frozen(struct task_struct *p) { return false; }
 155 static inline bool freezing(struct task_struct *p) { return false; }
 156
 157 static inline bool __refrigerator(bool check_kthr_stop) { return false; }
 158 static inline int freeze_processes(void) { BUG(); return 0; }
 159 static inline void thaw_processes(void) {}
 160
 161 static inline bool try_to_freeze(void) { return false; }
 162
 163 static inline void freezer_do_not_count(void) {}
 164 static inline void freezer_count(void) {}
 165 static inline int freezer_should_skip(struct task_struct *p) { return 0; }
 166 static inline void set_freezable(void) {}
 167 static inline void set_freezable_with_signal(void) {}
 168
 169 #define wait_event_freezable(wq, condition)                             \
 170                 wait_event_interruptible(wq, condition)
 171
 172 #define wait_event_freezable_timeout(wq, condition, timeout)            \
 173                 wait_event_interruptible_timeout(wq, condition, timeout)
 174
 175 #endif /* !CONFIG_FREEZER */
 176
 177 #endif  /* FREEZER_H_INCLUDED */