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 extern void thaw_kernel_threads(void);
  43
  44 static inline bool try_to_freeze(void)
  45 {
  46         might_sleep();
  47         if (likely(!freezing(current)))
  48                 return false;
  49         return __refrigerator(false);
  50 }
  51
  52 extern bool freeze_task(struct task_struct *p);
  53 extern bool set_freezable(void);
  54
  55 #ifdef CONFIG_CGROUP_FREEZER
  56 extern bool cgroup_freezing(struct task_struct *task);
  57 #else /* !CONFIG_CGROUP_FREEZER */
  58 static inline bool cgroup_freezing(struct task_struct *task)
  59 {
  60         return false;
  61 }
  62 #endif /* !CONFIG_CGROUP_FREEZER */
  63
  64 /*
  65  * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it
  66  * calls wait_for_completion(&vfork) and reset right after it returns from this
  67  * function.  Next, the parent should call try_to_freeze() to freeze itself
  68  * appropriately in case the child has exited before the freezing of tasks is
  69  * complete.  However, we don't want kernel threads to be frozen in unexpected
  70  * places, so we allow them to block freeze_processes() instead or to set
  71  * PF_NOFREEZE if needed. Fortunately, in the ____call_usermodehelper() case the
  72  * parent won't really block freeze_processes(), since ____call_usermodehelper()
  73  * (the child) does a little before exec/exit and it can't be frozen before
  74  * waking up the parent.
  75  */
  76
  77
  78 /* Tell the freezer not to count the current task as freezable. */
  79 static inline void freezer_do_not_count(void)
  80 {
  81         current->flags |= PF_FREEZER_SKIP;
  82 }
  83
  84 /*
  85  * Tell the freezer to count the current task as freezable again and try to
  86  * freeze it.
  87  */
  88 static inline void freezer_count(void)
  89 {
  90         current->flags &= ~PF_FREEZER_SKIP;
  91         try_to_freeze();
  92 }
  93
  94 /*
  95  * Check if the task should be counted as freezable by the freezer
  96  */
  97 static inline int freezer_should_skip(struct task_struct *p)
  98 {
  99         return !!(p->flags & PF_FREEZER_SKIP);
 100 }
 101
 102 /*
 103  * These macros are intended to be used whenever you want allow a task that's
 104  * sleeping in TASK_UNINTERRUPTIBLE or TASK_KILLABLE state to be frozen. Note
 105  * that neither return any clear indication of whether a freeze event happened
 106  * while in this function.
 107  */
 108
 109 /* Like schedule(), but should not block the freezer. */
 110 #define freezable_schedule()                                            \
 111 ({                                                                      \
 112         freezer_do_not_count();                                         \
 113         schedule();                                                     \
 114         freezer_count();                                                \
 115 })
 116
 117 /* Like schedule_timeout_killable(), but should not block the freezer. */
 118 #define freezable_schedule_timeout_killable(timeout)                    \
 119 ({                                                                      \
 120         long __retval;                                                  \
 121         freezer_do_not_count();                                         \
 122         __retval = schedule_timeout_killable(timeout);                  \
 123         freezer_count();                                                \
 124         __retval;                                                       \
 125 })
 126
 127 /*
 128  * Freezer-friendly wrappers around wait_event_interruptible(),
 129  * wait_event_killable() and wait_event_interruptible_timeout(), originally
 130  * defined in <linux/wait.h>
 131  */
 132
 133 #define wait_event_freezekillable(wq, condition)                        \
 134 ({                                                                      \
 135         int __retval;                                                   \
 136         freezer_do_not_count();                                         \
 137         __retval = wait_event_killable(wq, (condition));                \
 138         freezer_count();                                                \
 139         __retval;                                                       \
 140 })
 141
 142 #define wait_event_freezable(wq, condition)                             \
 143 ({                                                                      \
 144         int __retval;                                                   \
 145         for (;;) {                                                      \
 146                 __retval = wait_event_interruptible(wq,                 \
 147                                 (condition) || freezing(current));      \
 148                 if (__retval || (condition))                            \
 149                         break;                                          \
 150                 try_to_freeze();                                        \
 151         }                                                               \
 152         __retval;                                                       \
 153 })
 154
 155 #define wait_event_freezable_timeout(wq, condition, timeout)            \
 156 ({                                                                      \
 157         long __retval = timeout;                                        \
 158         for (;;) {                                                      \
 159                 __retval = wait_event_interruptible_timeout(wq,         \
 160                                 (condition) || freezing(current),       \
 161                                 __retval);                              \
 162                 if (__retval <= 0 || (condition))                       \
 163                         break;                                          \
 164                 try_to_freeze();                                        \
 165         }                                                               \
 166         __retval;                                                       \
 167 })
 168
 169 #else /* !CONFIG_FREEZER */
 170 static inline bool frozen(struct task_struct *p) { return false; }
 171 static inline bool freezing(struct task_struct *p) { return false; }
 172 static inline void __thaw_task(struct task_struct *t) {}
 173
 174 static inline bool __refrigerator(bool check_kthr_stop) { return false; }
 175 static inline int freeze_processes(void) { return -ENOSYS; }
 176 static inline int freeze_kernel_threads(void) { return -ENOSYS; }
 177 static inline void thaw_processes(void) {}
 178 static inline void thaw_kernel_threads(void) {}
 179
 180 static inline bool try_to_freeze(void) { return false; }
 181
 182 static inline void freezer_do_not_count(void) {}
 183 static inline void freezer_count(void) {}
 184 static inline int freezer_should_skip(struct task_struct *p) { return 0; }
 185 static inline void set_freezable(void) {}
 186
 187 #define freezable_schedule()  schedule()
 188
 189 #define freezable_schedule_timeout_killable(timeout)                    \
 190         schedule_timeout_killable(timeout)
 191
 192 #define wait_event_freezable(wq, condition)                             \
 193                 wait_event_interruptible(wq, condition)
 194
 195 #define wait_event_freezable_timeout(wq, condition, timeout)            \
 196                 wait_event_interruptible_timeout(wq, condition, timeout)
 197
 198 #define wait_event_freezekillable(wq, condition)                \
 199                 wait_event_killable(wq, condition)
 200
 201 #endif /* !CONFIG_FREEZER */
 202
 203 #endif  /* FREEZER_H_INCLUDED */