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