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git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - kernel/freezer.c
2 * kernel/freezer.c - Function to freeze a process
4 * Originally from kernel/power/process.c
7 #include <linux/interrupt.h>
8 #include <linux/suspend.h>
9 #include <linux/module.h>
10 #include <linux/syscalls.h>
11 #include <linux/freezer.h>
14 * freezing is complete, mark current process as frozen
16 static inline void frozen_process(void)
18 if (!unlikely(current
->flags
& PF_NOFREEZE
)) {
19 current
->flags
|= PF_FROZEN
;
22 clear_freeze_flag(current
);
25 /* Refrigerator is place where frozen processes are stored :-). */
26 void refrigerator(void)
28 /* Hmm, should we be allowed to suspend when there are realtime
33 if (freezing(current
)) {
40 save
= current
->state
;
41 pr_debug("%s entered refrigerator\n", current
->comm
);
43 spin_lock_irq(¤t
->sighand
->siglock
);
44 recalc_sigpending(); /* We sent fake signal, clean it up */
45 spin_unlock_irq(¤t
->sighand
->siglock
);
48 set_current_state(TASK_UNINTERRUPTIBLE
);
53 pr_debug("%s left refrigerator\n", current
->comm
);
54 __set_current_state(save
);
56 EXPORT_SYMBOL(refrigerator
);
58 static void fake_signal_wake_up(struct task_struct
*p
)
62 spin_lock_irqsave(&p
->sighand
->siglock
, flags
);
64 spin_unlock_irqrestore(&p
->sighand
->siglock
, flags
);
68 * freeze_task - send a freeze request to given task
69 * @p: task to send the request to
70 * @sig_only: if set, the request will only be sent if the task has the
71 * PF_FREEZER_NOSIG flag unset
72 * Return value: 'false', if @sig_only is set and the task has
73 * PF_FREEZER_NOSIG set or the task is frozen, 'true', otherwise
75 * The freeze request is sent by setting the tasks's TIF_FREEZE flag and
76 * either sending a fake signal to it or waking it up, depending on whether
77 * or not it has PF_FREEZER_NOSIG set. If @sig_only is set and the task
78 * has PF_FREEZER_NOSIG set (ie. it is a typical kernel thread), its
79 * TIF_FREEZE flag will not be set.
81 bool freeze_task(struct task_struct
*p
, bool sig_only
)
84 * We first check if the task is freezing and next if it has already
85 * been frozen to avoid the race with frozen_process() which first marks
86 * the task as frozen and next clears its TIF_FREEZE.
93 if (!sig_only
|| should_send_signal(p
))
99 if (should_send_signal(p
)) {
100 if (!signal_pending(p
))
101 fake_signal_wake_up(p
);
102 } else if (sig_only
) {
105 wake_up_state(p
, TASK_INTERRUPTIBLE
);
111 void cancel_freezing(struct task_struct
*p
)
116 pr_debug(" clean up: %s\n", p
->comm
);
117 clear_freeze_flag(p
);
118 spin_lock_irqsave(&p
->sighand
->siglock
, flags
);
119 recalc_sigpending_and_wake(p
);
120 spin_unlock_irqrestore(&p
->sighand
->siglock
, flags
);
125 * Wake up a frozen process
127 * task_lock() is needed to prevent the race with refrigerator() which may
128 * occur if the freezing of tasks fails. Namely, without the lock, if the
129 * freezing of tasks failed, thaw_tasks() might have run before a task in
130 * refrigerator() could call frozen_process(), in which case the task would be
131 * frozen and no one would thaw it.
133 int __thaw_process(struct task_struct
*p
)
136 p
->flags
&= ~PF_FROZEN
;
139 clear_freeze_flag(p
);
143 int thaw_process(struct task_struct
*p
)
146 if (__thaw_process(p
) == 1) {
154 EXPORT_SYMBOL(thaw_process
);