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 int freeze_kernel_threads(void);
  53 extern void thaw_processes(void);
  54
  55 static inline int try_to_freeze(void)
  56 {
  57         if (freezing(current)) {
  58                 refrigerator();
  59                 return 1;
  60         } else
  61                 return 0;
  62 }
  63
  64 extern bool freeze_task(struct task_struct *p, bool sig_only);
  65 extern void cancel_freezing(struct task_struct *p);
  66
  67 #ifdef CONFIG_CGROUP_FREEZER
  68 extern int cgroup_freezing_or_frozen(struct task_struct *task);
  69 #else /* !CONFIG_CGROUP_FREEZER */
  70 static inline int cgroup_freezing_or_frozen(struct task_struct *task)
  71 {
  72         return 0;
  73 }
  74 #endif /* !CONFIG_CGROUP_FREEZER */
  75
  76 /*
  77  * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it
  78  * calls wait_for_completion(&vfork) and reset right after it returns from this
  79  * function.  Next, the parent should call try_to_freeze() to freeze itself
  80  * appropriately in case the child has exited before the freezing of tasks is
  81  * complete.  However, we don't want kernel threads to be frozen in unexpected
  82  * places, so we allow them to block freeze_processes() instead or to set
  83  * PF_NOFREEZE if needed and PF_FREEZER_SKIP is only set for userland vfork
  84  * parents.  Fortunately, in the ____call_usermodehelper() case the parent won't
  85  * really block freeze_processes(), since ____call_usermodehelper() (the child)
  86  * does a little before exec/exit and it can't be frozen before waking up the
  87  * parent.
  88  */
  89
  90 /*
  91  * If the current task is a user space one, tell the freezer not to count it as
  92  * freezable.
  93  */
  94 static inline void freezer_do_not_count(void)
  95 {
  96         if (current->mm)
  97                 current->flags |= PF_FREEZER_SKIP;
  98 }
  99
 100 /*
 101  * If the current task is a user space one, tell the freezer to count it as
 102  * freezable again and try to freeze it.
 103  */
 104 static inline void freezer_count(void)
 105 {
 106         if (current->mm) {
 107                 current->flags &= ~PF_FREEZER_SKIP;
 108                 try_to_freeze();
 109         }
 110 }
 111
 112 /*
 113  * Check if the task should be counted as freezable by the freezer
 114  */
 115 static inline int freezer_should_skip(struct task_struct *p)
 116 {
 117         return !!(p->flags & PF_FREEZER_SKIP);
 118 }
 119
 120 /*
 121  * Tell the freezer that the current task should be frozen by it
 122  */
 123 static inline void set_freezable(void)
 124 {
 125         current->flags &= ~PF_NOFREEZE;
 126 }
 127
 128 /*
 129  * Tell the freezer that the current task should be frozen by it and that it
 130  * should send a fake signal to the task to freeze it.
 131  */
 132 static inline void set_freezable_with_signal(void)
 133 {
 134         current->flags &= ~(PF_NOFREEZE | PF_FREEZER_NOSIG);
 135 }
 136
 137 /*
 138  * Freezer-friendly wrappers around wait_event_interruptible() and
 139  * wait_event_interruptible_timeout(), originally defined in <linux/wait.h>
 140  */
 141
 142 #define wait_event_freezable(wq, condition)                             \
 143 ({                                                                      \
 144         int __retval;                                                   \
 145         do {                                                            \
 146                 __retval = wait_event_interruptible(wq,                 \
 147                                 (condition) || freezing(current));      \
 148                 if (__retval && !freezing(current))                     \
 149                         break;                                          \
 150                 else if (!(condition))                                  \
 151                         __retval = -ERESTARTSYS;                        \
 152         } while (try_to_freeze());                                      \
 153         __retval;                                                       \
 154 })
 155
 156
 157 #define wait_event_freezable_timeout(wq, condition, timeout)            \
 158 ({                                                                      \
 159         long __retval = timeout;                                        \
 160         do {                                                            \
 161                 __retval = wait_event_interruptible_timeout(wq,         \
 162                                 (condition) || freezing(current),       \
 163                                 __retval);                              \
 164         } while (try_to_freeze());                                      \
 165         __retval;                                                       \
 166 })
 167 #else /* !CONFIG_FREEZER */
 168 static inline int frozen(struct task_struct *p) { return 0; }
 169 static inline int freezing(struct task_struct *p) { return 0; }
 170 static inline void set_freeze_flag(struct task_struct *p) {}
 171 static inline void clear_freeze_flag(struct task_struct *p) {}
 172 static inline int thaw_process(struct task_struct *p) { return 1; }
 173
 174 static inline void refrigerator(void) {}
 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
 179 static inline int try_to_freeze(void) { return 0; }
 180
 181 static inline void freezer_do_not_count(void) {}
 182 static inline void freezer_count(void) {}
 183 static inline int freezer_should_skip(struct task_struct *p) { return 0; }
 184 static inline void set_freezable(void) {}
 185 static inline void set_freezable_with_signal(void) {}
 186
 187 #define wait_event_freezable(wq, condition)                             \
 188                 wait_event_interruptible(wq, condition)
 189
 190 #define wait_event_freezable_timeout(wq, condition, timeout)            \
 191                 wait_event_interruptible_timeout(wq, condition, timeout)
 192
 193 #endif /* !CONFIG_FREEZER */
 194
 195 #endif  /* FREEZER_H_INCLUDED */