[PATCH pm-freezer 4/4] freezer: use lock_task_sighand() in fake_signal_wake_up()
Tejun Heo
tj at kernel.org
Wed Aug 31 03:22:37 PDT 2011
cgroup_freezer calls freeze_task() without holding tasklist_lock and,
if the task is exiting, its ->sighand may be gone by the time
fake_signal_wake_up() is called. Use lock_task_sighand() instead of
accessing ->sighand directly.
Signed-off-by: Tejun Heo <tj at kernel.org>
Reported-by: Oleg Nesterov <oleg at redhat.com>
Cc: "Rafael J. Wysocki" <rjw at sisk.pl>
Cc: Paul Menage <paul at paulmenage.org>
---
kernel/freezer.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
Index: work/kernel/freezer.c
===================================================================
--- work.orig/kernel/freezer.c
+++ work/kernel/freezer.c
@@ -95,9 +95,10 @@ static void fake_signal_wake_up(struct t
{
unsigned long flags;
- spin_lock_irqsave(&p->sighand->siglock, flags);
- signal_wake_up(p, 0);
- spin_unlock_irqrestore(&p->sighand->siglock, flags);
+ if (lock_task_sighand(p, &flags)) {
+ signal_wake_up(p, 0);
+ unlock_task_sighand(p, &flags);
+ }
}
/**
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