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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/oom.h>
#include <linux/suspend.h>
#include <linux/module.h>
#include <linux/syscalls.h>
#include <linux/freezer.h>
#include <linux/delay.h>
#include <linux/workqueue.h>
/*
* Timeout for stopping processes
*/
#define TIMEOUT (20 * HZ)
static inline int freezable(struct task_struct * p)
{
if ((p == current) ||
(p->flags & PF_NOFREEZE))
return 0;
return 1;
}
static int try_to_freeze_tasks(bool sig_only)
{
struct task_struct *g, *p;
unsigned long end_time;
unsigned int todo;
bool wq_busy = false;
struct timeval start, end;
u64 elapsed_csecs64;
unsigned int elapsed_csecs;
bool wakeup = false;
do_gettimeofday(&start);
end_time = jiffies + TIMEOUT;
if (!sig_only)
freeze_workqueues_begin();
while (true) {
todo = 0;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (frozen(p) || !freezable(p))
continue;
if (!freeze_task(p, sig_only))
continue;
/*
* Now that we've done set_freeze_flag, don't
* perturb a task in TASK_STOPPED or TASK_TRACED.
* It is "frozen enough". If the task does wake
* up, it will immediately call try_to_freeze.
*
* Because freeze_task() goes through p's
* scheduler lock after setting TIF_FREEZE, it's
* guaranteed that either we see TASK_RUNNING or
* try_to_stop() after schedule() in ptrace/signal
* stop sees TIF_FREEZE.
*/
if (!task_is_stopped_or_traced(p) &&
!freezer_should_skip(p))
todo++;
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
if (!sig_only) {
wq_busy = freeze_workqueues_busy();
todo += wq_busy;
}
if (!todo || time_after(jiffies, end_time))
break;
if (pm_wakeup_pending()) {
wakeup = true;
break;
}
/*
* We need to retry, but first give the freezing tasks some
* time to enter the regrigerator.
*/
msleep(10);
}
do_gettimeofday(&end);
elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
do_div(elapsed_csecs64, NSEC_PER_SEC / 100);
elapsed_csecs = elapsed_csecs64;
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 tasks %s after %d.%02d seconds "
"(%d tasks refusing to freeze, wq_busy=%d):\n",
wakeup ? "aborted" : "failed",
elapsed_csecs / 100, elapsed_csecs % 100,
todo - wq_busy, wq_busy);
thaw_workqueues();
read_lock(&tasklist_lock);
do_each_thread(g, p) {
task_lock(p);
if (!wakeup && freezing(p) && !freezer_should_skip(p))
sched_show_task(p);
cancel_freezing(p);
task_unlock(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
} else {
printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100,
elapsed_csecs % 100);
}
return todo ? -EBUSY : 0;
}
/**
* freeze_processes - Signal user space processes to enter the refrigerator.
*/
int freeze_processes(void)
{
int error;
printk("Freezing user space processes ... ");
error = try_to_freeze_tasks(true);
if (!error) {
printk("done.");
oom_killer_disable();
}
printk("\n");
BUG_ON(in_atomic());
return error;
}
/**
* freeze_kernel_threads - Make freezable kernel threads go to the refrigerator.
*/
int freeze_kernel_threads(void)
{
int error;
printk("Freezing remaining freezable tasks ... ");
error = try_to_freeze_tasks(false);
if (!error)
printk("done.");
printk("\n");
BUG_ON(in_atomic());
return error;
}
void thaw_processes(void)
{
struct task_struct *g, *p;
oom_killer_enable();
printk("Restarting tasks ... ");
thaw_workqueues();
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (!freezable(p))
continue;
if (cgroup_freezing_or_frozen(p))
continue;
__thaw_task(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
schedule();
printk("done.\n");
}
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