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git.proxmox.com Git - mirror_ubuntu-eoan-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
);
47 /* prevent accounting of that task to load */
48 current
->flags
|= PF_FREEZING
;
51 set_current_state(TASK_UNINTERRUPTIBLE
);
57 /* Remove the accounting blocker */
58 current
->flags
&= ~PF_FREEZING
;
60 pr_debug("%s left refrigerator\n", current
->comm
);
61 __set_current_state(save
);
63 EXPORT_SYMBOL(refrigerator
);
65 static void fake_signal_wake_up(struct task_struct
*p
)
69 spin_lock_irqsave(&p
->sighand
->siglock
, flags
);
71 spin_unlock_irqrestore(&p
->sighand
->siglock
, flags
);
75 * freeze_task - send a freeze request to given task
76 * @p: task to send the request to
77 * @sig_only: if set, the request will only be sent if the task has the
78 * PF_FREEZER_NOSIG flag unset
79 * Return value: 'false', if @sig_only is set and the task has
80 * PF_FREEZER_NOSIG set or the task is frozen, 'true', otherwise
82 * The freeze request is sent by setting the tasks's TIF_FREEZE flag and
83 * either sending a fake signal to it or waking it up, depending on whether
84 * or not it has PF_FREEZER_NOSIG set. If @sig_only is set and the task
85 * has PF_FREEZER_NOSIG set (ie. it is a typical kernel thread), its
86 * TIF_FREEZE flag will not be set.
88 bool freeze_task(struct task_struct
*p
, bool sig_only
)
91 * We first check if the task is freezing and next if it has already
92 * been frozen to avoid the race with frozen_process() which first marks
93 * the task as frozen and next clears its TIF_FREEZE.
100 if (!sig_only
|| should_send_signal(p
))
106 if (should_send_signal(p
)) {
107 if (!signal_pending(p
))
108 fake_signal_wake_up(p
);
109 } else if (sig_only
) {
112 wake_up_state(p
, TASK_INTERRUPTIBLE
);
118 void cancel_freezing(struct task_struct
*p
)
123 pr_debug(" clean up: %s\n", p
->comm
);
124 clear_freeze_flag(p
);
125 spin_lock_irqsave(&p
->sighand
->siglock
, flags
);
126 recalc_sigpending_and_wake(p
);
127 spin_unlock_irqrestore(&p
->sighand
->siglock
, flags
);
131 static int __thaw_process(struct task_struct
*p
)
134 p
->flags
&= ~PF_FROZEN
;
137 clear_freeze_flag(p
);
142 * Wake up a frozen process
144 * task_lock() is needed to prevent the race with refrigerator() which may
145 * occur if the freezing of tasks fails. Namely, without the lock, if the
146 * freezing of tasks failed, thaw_tasks() might have run before a task in
147 * refrigerator() could call frozen_process(), in which case the task would be
148 * frozen and no one would thaw it.
150 int thaw_process(struct task_struct
*p
)
153 if (__thaw_process(p
) == 1) {
161 EXPORT_SYMBOL(thaw_process
);