linux/kernel/power/process.c
Rafael J. Wysocki a7ef7878ea [PATCH] Make suspend possible with a traced process at a breakpoint
It should be possible to suspend, either to RAM or to disk, if there's a
traced process that has just reached a breakpoint.  However, this is a
special case, because its parent process might have been frozen already and
then we are unable to deliver the "freeze" signal to the traced process.
If this happens, it's better to cancel the freezing of the traced process.

Ref. http://bugzilla.kernel.org/show_bug.cgi?id=6787

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-08-06 08:57:45 -07:00

174 lines
3.9 KiB
C

/*
* drivers/power/process.c - Functions for starting/stopping processes on
* suspend transitions.
*
* Originally from swsusp.
*/
#undef DEBUG
#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/suspend.h>
#include <linux/module.h>
#include <linux/syscalls.h>
/*
* Timeout for stopping processes
*/
#define TIMEOUT (20 * HZ)
static inline int freezeable(struct task_struct * p)
{
if ((p == current) ||
(p->flags & PF_NOFREEZE) ||
(p->exit_state == EXIT_ZOMBIE) ||
(p->exit_state == EXIT_DEAD) ||
(p->state == TASK_STOPPED))
return 0;
return 1;
}
/* 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;
save = current->state;
pr_debug("%s entered refrigerator\n", current->comm);
printk("=");
frozen_process(current);
spin_lock_irq(&current->sighand->siglock);
recalc_sigpending(); /* We sent fake signal, clean it up */
spin_unlock_irq(&current->sighand->siglock);
while (frozen(current)) {
current->state = TASK_UNINTERRUPTIBLE;
schedule();
}
pr_debug("%s left refrigerator\n", current->comm);
current->state = save;
}
static inline void freeze_process(struct task_struct *p)
{
unsigned long flags;
if (!freezing(p)) {
freeze(p);
spin_lock_irqsave(&p->sighand->siglock, flags);
signal_wake_up(p, 0);
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);
do_not_freeze(p);
spin_lock_irqsave(&p->sighand->siglock, flags);
recalc_sigpending_tsk(p);
spin_unlock_irqrestore(&p->sighand->siglock, flags);
}
}
/* 0 = success, else # of processes that we failed to stop */
int freeze_processes(void)
{
int todo, nr_user, user_frozen;
unsigned long start_time;
struct task_struct *g, *p;
printk( "Stopping tasks: " );
start_time = jiffies;
user_frozen = 0;
do {
nr_user = todo = 0;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (!freezeable(p))
continue;
if (frozen(p))
continue;
if (p->state == TASK_TRACED && frozen(p->parent)) {
cancel_freezing(p);
continue;
}
if (p->mm && !(p->flags & PF_BORROWED_MM)) {
/* The task is a user-space one.
* Freeze it unless there's a vfork completion
* pending
*/
if (!p->vfork_done)
freeze_process(p);
nr_user++;
} else {
/* Freeze only if the user space is frozen */
if (user_frozen)
freeze_process(p);
todo++;
}
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
todo += nr_user;
if (!user_frozen && !nr_user) {
sys_sync();
start_time = jiffies;
}
user_frozen = !nr_user;
yield(); /* Yield is okay here */
if (todo && time_after(jiffies, start_time + TIMEOUT))
break;
} while(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.
*/
if (todo) {
printk( "\n" );
printk(KERN_ERR " stopping tasks timed out "
"after %d seconds (%d tasks remaining):\n",
TIMEOUT / HZ, todo);
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (freezeable(p) && !frozen(p))
printk(KERN_ERR " %s\n", p->comm);
cancel_freezing(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
return todo;
}
printk( "|\n" );
BUG_ON(in_atomic());
return 0;
}
void thaw_processes(void)
{
struct task_struct *g, *p;
printk( "Restarting tasks..." );
read_lock(&tasklist_lock);
do_each_thread(g, p) {
if (!freezeable(p))
continue;
if (!thaw_process(p))
printk(KERN_INFO " Strange, %s not stopped\n", p->comm );
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
schedule();
printk( " done\n" );
}
EXPORT_SYMBOL(refrigerator);