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_freezing_or_frozen(struct task_struct *task);
  68 #else /* !CONFIG_CGROUP_FREEZER */
  69 static inline int cgroup_freezing_or_frozen(struct task_struct *task)
  70 {
  71         return 0;
  72 }
  73 #endif /* !CONFIG_CGROUP_FREEZER */
  74
  75 /*
  76  * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it
  77  * calls wait_for_completion(&vfork) and reset right after it returns from this
  78  * function.  Next, the parent should call try_to_freeze() to freeze itself
  79  * appropriately in case the child has exited before the freezing of tasks is
  80  * complete.  However, we don't want kernel threads to be frozen in unexpected
  81  * places, so we allow them to block freeze_processes() instead or to set
  82  * PF_NOFREEZE if needed and PF_FREEZER_SKIP is only set for userland vfork
  83  * parents.  Fortunately, in the ____call_usermodehelper() case the parent won't
  84  * really block freeze_processes(), since ____call_usermodehelper() (the child)
  85  * does a little before exec/exit and it can't be frozen before waking up the
  86  * parent.
  87  */
  88
  89 /*
  90  * If the current task is a user space one, tell the freezer not to count it as
  91  * freezable.
  92  */
  93 static inline void freezer_do_not_count(void)
  94 {
  95         if (current->mm)
  96                 current->flags |= PF_FREEZER_SKIP;
  97 }
  98
  99 /*
 100  * If the current task is a user space one, tell the freezer to count it as
 101  * freezable again and try to freeze it.
 102  */
 103 static inline void freezer_count(void)
 104 {
 105         if (current->mm) {
 106                 current->flags &= ~PF_FREEZER_SKIP;
 107                 try_to_freeze();
 108         }
 109 }
 110
 111 /*
 112  * Check if the task should be counted as freezable by the freezer
 113  */
 114 static inline int freezer_should_skip(struct task_struct *p)
 115 {
 116         return !!(p->flags & PF_FREEZER_SKIP);
 117 }
 118
 119 /*
 120  * Tell the freezer that the current task should be frozen by it
 121  */
 122 static inline void set_freezable(void)
 123 {
 124         current->flags &= ~PF_NOFREEZE;
 125 }
 126
 127 /*
 128  * Tell the freezer that the current task should be frozen by it and that it
 129  * should send a fake signal to the task to freeze it.
 130  */
 131 static inline void set_freezable_with_signal(void)
 132 {
 133         current->flags &= ~(PF_NOFREEZE | PF_FREEZER_NOSIG);
 134 }
 135
 136 /*
 137  * Freezer-friendly wrappers around wait_event_interruptible() and
 138  * wait_event_interruptible_timeout(), originally defined in <linux/wait.h>
 139  */
 140
 141 #define wait_event_freezable(wq, condition)                             \
 142 ({                                                                      \
 143         int __retval;                                                   \
 144         do {                                                            \
 145                 __retval = wait_event_interruptible(wq,                 \
 146                                 (condition) || freezing(current));      \
 147                 if (__retval && !freezing(current))                     \
 148                         break;                                          \
 149                 else if (!(condition))                                  \
 150                         __retval = -ERESTARTSYS;                        \
 151         } while (try_to_freeze());                                      \
 152         __retval;                                                       \
 153 })
 154
 155
 156 #define wait_event_freezable_timeout(wq, condition, timeout)            \
 157 ({                                                                      \
 158         long __retval = timeout;                                        \
 159         do {                                                            \
 160                 __retval = wait_event_interruptible_timeout(wq,         \
 161                                 (condition) || freezing(current),       \
 162                                 __retval);                              \
 163         } while (try_to_freeze());                                      \
 164         __retval;                                                       \
 165 })
 166 #else /* !CONFIG_FREEZER */
 167 static inline int frozen(struct task_struct *p) { return 0; }
 168 static inline int freezing(struct task_struct *p) { return 0; }
 169 static inline void set_freeze_flag(struct task_struct *p) {}
 170 static inline void clear_freeze_flag(struct task_struct *p) {}
 171 static inline int thaw_process(struct task_struct *p) { return 1; }
 172
 173 static inline void refrigerator(void) {}
 174 static inline int freeze_processes(void) { BUG(); return 0; }
 175 static inline void thaw_processes(void) {}
 176
 177 static inline int try_to_freeze(void) { return 0; }
 178
 179 static inline void freezer_do_not_count(void) {}
 180 static inline void freezer_count(void) {}
 181 static inline int freezer_should_skip(struct task_struct *p) { return 0; }
 182 static inline void set_freezable(void) {}
 183 static inline void set_freezable_with_signal(void) {}
 184
 185 #define wait_event_freezable(wq, condition)                             \
 186                 wait_event_interruptible(wq, condition)
 187
 188 #define wait_event_freezable_timeout(wq, condition, timeout)            \
 189                 wait_event_interruptible_timeout(wq, condition, timeout)
 190
 191 #endif /* !CONFIG_FREEZER */
 192
 193 #endif  /* FREEZER_H_INCLUDED */