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
   9 #ifdef CONFIG_FREEZER
  10 /*
  11  * Check if a process has been frozen
  12  */
  13 static inline int frozen(struct task_struct *p)
  14 {
  15         return p->flags & PF_FROZEN;
  16 }
  17
  18 /*
  19  * Check if there is a request to freeze a process
  20  */
  21 static inline int freezing(struct task_struct *p)
  22 {
  23         return test_tsk_thread_flag(p, TIF_FREEZE);
  24 }
  25
  26 /*
  27  * Request that a process be frozen
  28  */
  29 static inline void set_freeze_flag(struct task_struct *p)
  30 {
  31         set_tsk_thread_flag(p, TIF_FREEZE);
  32 }
  33
  34 /*
  35  * Sometimes we may need to cancel the previous 'freeze' request
  36  */
  37 static inline void clear_freeze_flag(struct task_struct *p)
  38 {
  39         clear_tsk_thread_flag(p, TIF_FREEZE);
  40 }
  41
  42 static inline bool should_send_signal(struct task_struct *p)
  43 {
  44         return !(p->flags & PF_FREEZER_NOSIG);
  45 }
  46
  47 /* Takes and releases task alloc lock using task_lock() */
  48 extern int thaw_process(struct task_struct *p);
  49
  50 extern void refrigerator(void);
  51 extern int freeze_processes(void);
  52 extern void thaw_processes(void);
  53
  54 static inline int try_to_freeze(void)
  55 {
  56         if (freezing(current)) {
  57                 refrigerator();
  58                 return 1;
  59         } else
  60                 return 0;
  61 }
  62
  63 extern bool freeze_task(struct task_struct *p, bool sig_only);
  64 extern void cancel_freezing(struct task_struct *p);
  65
  66 #ifdef CONFIG_CGROUP_FREEZER
  67 extern int cgroup_frozen(struct task_struct *task);
  68 #else /* !CONFIG_CGROUP_FREEZER */
  69 static inline int cgroup_frozen(struct task_struct *task) { return 0; }
  70 #endif /* !CONFIG_CGROUP_FREEZER */
  71
  72 /*
  73  * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it
  74  * calls wait_for_completion(&vfork) and reset right after it returns from this
  75  * function.  Next, the parent should call try_to_freeze() to freeze itself
  76  * appropriately in case the child has exited before the freezing of tasks is
  77  * complete.  However, we don't want kernel threads to be frozen in unexpected
  78  * places, so we allow them to block freeze_processes() instead or to set
  79  * PF_NOFREEZE if needed and PF_FREEZER_SKIP is only set for userland vfork
  80  * parents.  Fortunately, in the ____call_usermodehelper() case the parent won't
  81  * really block freeze_processes(), since ____call_usermodehelper() (the child)
  82  * does a little before exec/exit and it can't be frozen before waking up the
  83  * parent.
  84  */
  85
  86 /*
  87  * If the current task is a user space one, tell the freezer not to count it as
  88  * freezable.
  89  */
  90 static inline void freezer_do_not_count(void)
  91 {
  92         if (current->mm)
  93                 current->flags |= PF_FREEZER_SKIP;
  94 }
  95
  96 /*
  97  * If the current task is a user space one, tell the freezer to count it as
  98  * freezable again and try to freeze it.
  99  */
 100 static inline void freezer_count(void)
 101 {
 102         if (current->mm) {
 103                 current->flags &= ~PF_FREEZER_SKIP;
 104                 try_to_freeze();
 105         }
 106 }
 107
 108 /*
 109  * Check if the task should be counted as freezeable by the freezer
 110  */
 111 static inline int freezer_should_skip(struct task_struct *p)
 112 {
 113         return !!(p->flags & PF_FREEZER_SKIP);
 114 }
 115
 116 /*
 117  * Tell the freezer that the current task should be frozen by it
 118  */
 119 static inline void set_freezable(void)
 120 {
 121         current->flags &= ~PF_NOFREEZE;
 122 }
 123
 124 /*
 125  * Tell the freezer that the current task should be frozen by it and that it
 126  * should send a fake signal to the task to freeze it.
 127  */
 128 static inline void set_freezable_with_signal(void)
 129 {
 130         current->flags &= ~(PF_NOFREEZE | PF_FREEZER_NOSIG);
 131 }
 132
 133 /*
 134  * Freezer-friendly wrappers around wait_event_interruptible() and
 135  * wait_event_interruptible_timeout(), originally defined in <linux/wait.h>
 136  */
 137
 138 #define wait_event_freezable(wq, condition)                             \
 139 ({                                                                      \
 140         int __retval;                                                   \
 141         do {                                                            \
 142                 __retval = wait_event_interruptible(wq,                 \
 143                                 (condition) || freezing(current));      \
 144                 if (__retval && !freezing(current))                     \
 145                         break;                                          \
 146                 else if (!(condition))                                  \
 147                         __retval = -ERESTARTSYS;                        \
 148         } while (try_to_freeze());                                      \
 149         __retval;                                                       \
 150 })
 151
 152
 153 #define wait_event_freezable_timeout(wq, condition, timeout)            \
 154 ({                                                                      \
 155         long __retval = timeout;                                        \
 156         do {                                                            \
 157                 __retval = wait_event_interruptible_timeout(wq,         \
 158                                 (condition) || freezing(current),       \
 159                                 __retval);                              \
 160         } while (try_to_freeze());                                      \
 161         __retval;                                                       \
 162 })
 163 #else /* !CONFIG_FREEZER */
 164 static inline int frozen(struct task_struct *p) { return 0; }
 165 static inline int freezing(struct task_struct *p) { return 0; }
 166 static inline void set_freeze_flag(struct task_struct *p) {}
 167 static inline void clear_freeze_flag(struct task_struct *p) {}
 168 static inline int thaw_process(struct task_struct *p) { return 1; }
 169
 170 static inline void refrigerator(void) {}
 171 static inline int freeze_processes(void) { BUG(); return 0; }
 172 static inline void thaw_processes(void) {}
 173
 174 static inline int try_to_freeze(void) { return 0; }
 175
 176 static inline void freezer_do_not_count(void) {}
 177 static inline void freezer_count(void) {}
 178 static inline int freezer_should_skip(struct task_struct *p) { return 0; }
 179 static inline void set_freezable(void) {}
 180 static inline void set_freezable_with_signal(void) {}
 181
 182 #define wait_event_freezable(wq, condition)                             \
 183                 wait_event_interruptible(wq, condition)
 184
 185 #define wait_event_freezable_timeout(wq, condition, timeout)            \
 186                 wait_event_interruptible_timeout(wq, condition, timeout)
 187
 188 #endif /* !CONFIG_FREEZER */
 189
 190 #endif  /* FREEZER_H_INCLUDED */