1 /* Freezer declarations */
3 #include <linux/sched.h>
7 * Check if a process has been frozen
9 static inline int frozen(struct task_struct *p)
11 return p->flags & PF_FROZEN;
15 * Check if there is a request to freeze a process
17 static inline int freezing(struct task_struct *p)
19 return test_tsk_thread_flag(p, TIF_FREEZE);
23 * Request that a process be frozen
25 static inline void freeze(struct task_struct *p)
27 set_tsk_thread_flag(p, TIF_FREEZE);
31 * Sometimes we may need to cancel the previous 'freeze' request
33 static inline void do_not_freeze(struct task_struct *p)
35 clear_tsk_thread_flag(p, TIF_FREEZE);
39 * Wake up a frozen process
41 * task_lock() is taken to prevent the race with refrigerator() which may
42 * occur if the freezing of tasks fails. Namely, without the lock, if the
43 * freezing of tasks failed, thaw_tasks() might have run before a task in
44 * refrigerator() could call frozen_process(), in which case the task would be
45 * frozen and no one would thaw it.
47 static inline int thaw_process(struct task_struct *p)
51 p->flags &= ~PF_FROZEN;
56 clear_tsk_thread_flag(p, TIF_FREEZE);
62 * freezing is complete, mark process as frozen
64 static inline void frozen_process(struct task_struct *p)
66 p->flags |= PF_FROZEN;
68 clear_tsk_thread_flag(p, TIF_FREEZE);
71 extern void refrigerator(void);
72 extern int freeze_processes(void);
73 extern void thaw_processes(void);
75 static inline int try_to_freeze(void)
77 if (freezing(current)) {
85 * The PF_FREEZER_SKIP flag should be set by a vfork parent right before it
86 * calls wait_for_completion(&vfork) and reset right after it returns from this
87 * function. Next, the parent should call try_to_freeze() to freeze itself
88 * appropriately in case the child has exited before the freezing of tasks is
89 * complete. However, we don't want kernel threads to be frozen in unexpected
90 * places, so we allow them to block freeze_processes() instead or to set
91 * PF_NOFREEZE if needed and PF_FREEZER_SKIP is only set for userland vfork
92 * parents. Fortunately, in the ____call_usermodehelper() case the parent won't
93 * really block freeze_processes(), since ____call_usermodehelper() (the child)
94 * does a little before exec/exit and it can't be frozen before waking up the
99 * If the current task is a user space one, tell the freezer not to count it as
102 static inline void freezer_do_not_count(void)
105 current->flags |= PF_FREEZER_SKIP;
109 * If the current task is a user space one, tell the freezer to count it as
110 * freezable again and try to freeze it.
112 static inline void freezer_count(void)
115 current->flags &= ~PF_FREEZER_SKIP;
121 * Check if the task should be counted as freezeable by the freezer
123 static inline int freezer_should_skip(struct task_struct *p)
125 return !!(p->flags & PF_FREEZER_SKIP);
129 static inline int frozen(struct task_struct *p) { return 0; }
130 static inline int freezing(struct task_struct *p) { return 0; }
131 static inline void freeze(struct task_struct *p) { BUG(); }
132 static inline int thaw_process(struct task_struct *p) { return 1; }
133 static inline void frozen_process(struct task_struct *p) { BUG(); }
135 static inline void refrigerator(void) {}
136 static inline int freeze_processes(void) { BUG(); return 0; }
137 static inline void thaw_processes(void) {}
139 static inline int try_to_freeze(void) { return 0; }
141 static inline void freezer_do_not_count(void) {}
142 static inline void freezer_count(void) {}
143 static inline int freezer_should_skip(struct task_struct *p) { return 0; }