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-rw-r--r--include/linux/freezer.h10
-rw-r--r--kernel/power/process.c12
2 files changed, 21 insertions, 1 deletions
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index 5e75e26..db5423e 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -37,14 +37,24 @@ static inline void do_not_freeze(struct task_struct *p)
/*
* Wake up a frozen process
+ *
+ * task_lock() is taken to prevent the race with refrigerator() which may
+ * occur if the freezing of tasks fails. Namely, without the lock, if the
+ * freezing of tasks failed, thaw_tasks() might have run before a task in
+ * refrigerator() could call frozen_process(), in which case the task would be
+ * frozen and no one would thaw it.
*/
static inline int thaw_process(struct task_struct *p)
{
+ task_lock(p);
if (frozen(p)) {
p->flags &= ~PF_FROZEN;
+ task_unlock(p);
wake_up_process(p);
return 1;
}
+ clear_tsk_thread_flag(p, TIF_FREEZE);
+ task_unlock(p);
return 0;
}
diff --git a/kernel/power/process.c b/kernel/power/process.c
index 0884193..02e490e 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -37,10 +37,18 @@ 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(current);
+ task_unlock(current);
+ } else {
+ task_unlock(current);
+ return;
+ }
save = current->state;
pr_debug("%s entered refrigerator\n", current->comm);
- frozen_process(current);
spin_lock_irq(&current->sighand->siglock);
recalc_sigpending(); /* We sent fake signal, clean it up */
spin_unlock_irq(&current->sighand->siglock);
@@ -152,10 +160,12 @@ static unsigned int try_to_freeze_tasks(int freeze_user_space)
if (is_user_space(p) == !freeze_user_space)
continue;
+ task_lock(p);
if (freezeable(p) && !frozen(p))
printk(KERN_ERR " %s\n", p->comm);
cancel_freezing(p);
+ task_unlock(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
}
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