1 /* Freezer declarations */
3 #ifndef FREEZER_H_INCLUDED
4 #define FREEZER_H_INCLUDED
6 #include <linux/sched.h>
7 #include <linux/wait.h>
11 * Check if a process has been frozen
13 static inline int frozen(struct task_struct *p)
15 return p->flags & PF_FROZEN;
19 * Check if there is a request to freeze a process
21 static inline int freezing(struct task_struct *p)
23 return test_tsk_thread_flag(p, TIF_FREEZE);
27 * Request that a process be frozen
29 static inline void set_freeze_flag(struct task_struct *p)
31 set_tsk_thread_flag(p, TIF_FREEZE);
35 * Sometimes we may need to cancel the previous 'freeze' request
37 static inline void clear_freeze_flag(struct task_struct *p)
39 clear_tsk_thread_flag(p, TIF_FREEZE);
42 static inline bool should_send_signal(struct task_struct *p)
44 return !(p->flags & PF_FREEZER_NOSIG);
48 * Wake up a frozen process
50 * task_lock() is taken to prevent the race with refrigerator() which may
51 * occur if the freezing of tasks fails. Namely, without the lock, if the
52 * freezing of tasks failed, thaw_tasks() might have run before a task in
53 * refrigerator() could call frozen_process(), in which case the task would be
54 * frozen and no one would thaw it.
56 static inline int thaw_process(struct task_struct *p)
60 p->flags &= ~PF_FROZEN;
70 extern void refrigerator(void);
71 extern int freeze_processes(void);
72 extern void thaw_processes(void);
74 static inline int try_to_freeze(void)
76 if (freezing(current)) {
83 extern bool freeze_task(struct task_struct *p, bool sig_only);
84 extern void cancel_freezing(struct task_struct *p);
87 * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it
88 * calls wait_for_completion(&vfork) and reset right after it returns from this
89 * function. Next, the parent should call try_to_freeze() to freeze itself
90 * appropriately in case the child has exited before the freezing of tasks is
91 * complete. However, we don't want kernel threads to be frozen in unexpected
92 * places, so we allow them to block freeze_processes() instead or to set
93 * PF_NOFREEZE if needed and PF_FREEZER_SKIP is only set for userland vfork
94 * parents. Fortunately, in the ____call_usermodehelper() case the parent won't
95 * really block freeze_processes(), since ____call_usermodehelper() (the child)
96 * does a little before exec/exit and it can't be frozen before waking up the
101 * If the current task is a user space one, tell the freezer not to count it as
104 static inline void freezer_do_not_count(void)
107 current->flags |= PF_FREEZER_SKIP;
111 * If the current task is a user space one, tell the freezer to count it as
112 * freezable again and try to freeze it.
114 static inline void freezer_count(void)
117 current->flags &= ~PF_FREEZER_SKIP;
123 * Check if the task should be counted as freezeable by the freezer
125 static inline int freezer_should_skip(struct task_struct *p)
127 return !!(p->flags & PF_FREEZER_SKIP);
131 * Tell the freezer that the current task should be frozen by it
133 static inline void set_freezable(void)
135 current->flags &= ~PF_NOFREEZE;
139 * Tell the freezer that the current task should be frozen by it and that it
140 * should send a fake signal to the task to freeze it.
142 static inline void set_freezable_with_signal(void)
144 current->flags &= ~(PF_NOFREEZE | PF_FREEZER_NOSIG);
148 * Freezer-friendly wrappers around wait_event_interruptible() and
149 * wait_event_interruptible_timeout(), originally defined in <linux/wait.h>
152 #define wait_event_freezable(wq, condition) \
156 __retval = wait_event_interruptible(wq, \
157 (condition) || freezing(current)); \
158 if (__retval && !freezing(current)) \
160 else if (!(condition)) \
161 __retval = -ERESTARTSYS; \
162 } while (try_to_freeze()); \
167 #define wait_event_freezable_timeout(wq, condition, timeout) \
169 long __retval = timeout; \
171 __retval = wait_event_interruptible_timeout(wq, \
172 (condition) || freezing(current), \
174 } while (try_to_freeze()); \
177 #else /* !CONFIG_FREEZER */
178 static inline int frozen(struct task_struct *p) { return 0; }
179 static inline int freezing(struct task_struct *p) { return 0; }
180 static inline void set_freeze_flag(struct task_struct *p) {}
181 static inline void clear_freeze_flag(struct task_struct *p) {}
182 static inline int thaw_process(struct task_struct *p) { return 1; }
184 static inline void refrigerator(void) {}
185 static inline int freeze_processes(void) { BUG(); return 0; }
186 static inline void thaw_processes(void) {}
188 static inline int try_to_freeze(void) { return 0; }
190 static inline void freezer_do_not_count(void) {}
191 static inline void freezer_count(void) {}
192 static inline int freezer_should_skip(struct task_struct *p) { return 0; }
193 static inline void set_freezable(void) {}
194 static inline void set_freezable_with_signal(void) {}
196 #define wait_event_freezable(wq, condition) \
197 wait_event_interruptible(wq, condition)
199 #define wait_event_freezable_timeout(wq, condition, timeout) \
200 wait_event_interruptible_timeout(wq, condition, timeout)
202 #endif /* !CONFIG_FREEZER */
204 #endif /* FREEZER_H_INCLUDED */