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[4/6] freezer: use lock_task_sighand() in fake_signal_wake_up()

Message ID 1314988070-12244-5-git-send-email-tj@kernel.org (mailing list archive)
State Not Applicable, archived
Headers show

Commit Message

Tejun Heo Sept. 2, 2011, 6:27 p.m. UTC
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@kernel.org>
Reported-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Paul Menage <paul@paulmenage.org>
---
 kernel/freezer.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)
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Patch

diff --git a/kernel/freezer.c b/kernel/freezer.c
index ebee1ab..9846133 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -93,9 +93,10 @@  static void fake_signal_wake_up(struct task_struct *p)
 {
 	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);
+	}
 }
 
 /**