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-rw-r--r--include/linux/freezer.h10
1 files changed, 10 insertions, 0 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;
}