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/*
* drivers/power/process.c - Functions for starting/stopping processes on
* suspend transitions.
*
* Originally from swsusp.
*/
#undef DEBUG
#include <linux/interrupt.h>
#include <linux/suspend.h>
#include <linux/module.h>
#include <linux/syscalls.h>
#include <linux/freezer.h>
/*
* Timeout for stopping processes
*/
#define TIMEOUT (20 * HZ)
#define FREEZER_KERNEL_THREADS 0
#define FREEZER_USER_SPACE 1
static inline int freezeable(struct task_struct * p)
{
if ((p == current) ||
(p->flags & PF_NOFREEZE) ||
(p->exit_state != 0))
return 0;
return 1;
}
/*
* freezing is complete, mark current process as frozen
*/
static inline void frozen_process(void)
{
if (!unlikely(current->flags & PF_NOFREEZE)) {
current->flags |= PF_FROZEN;
wmb();
}
clear_freeze_flag(current);
}
/* Refrigerator is place where frozen processes are stored :-). */
void refrigerator(void)
{
/* Hmm, should we be allowed to suspend when there are realtime
processes around? */
long save;
task_lock(current);
if (freezing(current)) {
frozen_process();
task_unlock(current);
} else {
task_unlock(current);
return;
}
save = current->state;
pr_debug("%s entered refrigerator\n", current->comm);
spin_lock_irq(¤t->sighand->siglock);
recalc_sigpending(); /* We sent fake signal, clean it up */
spin_unlock_irq(¤t->sighand->siglock);
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (!frozen(current))
break;
schedule();
}
pr_debug("%s left refrigerator\n", current->comm);
__set_current_state(save);
}
static void freeze_task(struct task_struct *p)
{
unsigned long flags;
if (!freezing(p)) {
rmb();
if (!frozen(p)) {
set_freeze_flag(p);
if (p->state == TASK_STOPPED)
force_sig_specific(SIGSTOP, p);
spin_lock_irqsave(&p->sighand->siglock, flags);
signal_wake_up(p, p->state == TASK_STOPPED);
spin_unlock_irqrestore(&p->sighand->siglock, flags);
}
}
}
static void cancel_freezing(struct task_struct *p)
{
unsigned long flags;
if (freezing(p)) {
pr_debug(" clean up: %s\n", p->comm);
clear_freeze_flag(p);
spin_lock_irqsave(&p->sighand->siglock, flags);
recalc_sigpending_and_wake(p);
spin_unlock_irqrestore(&p->sighand->siglock, flags);
}
}
static int try_to_freeze_tasks(int freeze_user_space)
{
struct task_struct *g, *p;
unsigned long end_time;
unsigned int todo;
end_time = jiffies + TIMEOUT;
do {
todo = 0;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (frozen(p) || !freezeable(p))
continue;
if (freeze_user_space) {
if (p->state == TASK_TRACED &&
frozen(p->parent)) {
cancel_freezing(p);
continue;
}
/*
* Kernel threads should not have TIF_FREEZE set
* at this point, so we must ensure that either
* p->mm is not NULL *and* PF_BORROWED_MM is
* unset, or TIF_FRREZE is left unset.
* The task_lock() is necessary to prevent races
* with exit_mm() or use_mm()/unuse_mm() from
* occuring.
*/
task_lock(p);
if (!p->mm || (p->flags & PF_BORROWED_MM)) {
task_unlock(p);
continue;
}
freeze_task(p);
task_unlock(p);
} else {
freeze_task(p);
}
if (!freezer_should_skip(p))
todo++;
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
yield(); /* Yield is okay here */
if (time_after(jiffies, end_time))
break;
} while (todo);
if (todo) {
/* This does not unfreeze processes that are already frozen
* (we have slightly ugly calling convention in that respect,
* and caller must call thaw_processes() if something fails),
* but it cleans up leftover PF_FREEZE requests.
*/
printk("\n");
printk(KERN_ERR "Freezing of %s timed out after %d seconds "
"(%d tasks refusing to freeze):\n",
freeze_user_space ? "user space " : "tasks ",
TIMEOUT / HZ, todo);
show_state();
read_lock(&tasklist_lock);
do_each_thread(g, p) {
task_lock(p);
if (freezing(p) && !freezer_should_skip(p))
printk(KERN_ERR " %s\n", p->comm);
cancel_freezing(p);
task_unlock(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
}
return todo ? -EBUSY : 0;
}
/**
* freeze_processes - tell processes to enter the refrigerator
*/
int freeze_processes(void)
{
int error;
printk("Stopping tasks ... ");
error = try_to_freeze_tasks(FREEZER_USER_SPACE);
if (error)
return error;
error = try_to_freeze_tasks(FREEZER_KERNEL_THREADS);
if (error)
return error;
printk("done.\n");
BUG_ON(in_atomic());
return 0;
}
static void thaw_tasks(int thaw_user_space)
{
struct task_struct *g, *p;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (!freezeable(p))
continue;
if (!p->mm == thaw_user_space)
continue;
thaw_process(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
}
void thaw_processes(void)
{
printk("Restarting tasks ... ");
thaw_tasks(FREEZER_KERNEL_THREADS);
thaw_tasks(FREEZER_USER_SPACE);
schedule();
printk("done.\n");
}
EXPORT_SYMBOL(refrigerator);
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