From 944629794b0b3845929ad98e89e1fff381add883 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@redhat.com>
Date: Mon, 10 Nov 2008 15:39:30 +0100
Subject: [PATCH] --- yaml --- r: 118767 b: refs/heads/master c:
 ad474caca3e2a0550b7ce0706527ad5ab389a4d4 h: refs/heads/master i:   118765:
 422f00e198f6a5edd67af428e3f895259a65722d   118763:
 0cd7c57dec77b389128a53909382be15ad58b0ef   118759:
 742c56a85c0bb20f84708ba246626cf4025900a0   118751:
 c19cbaca19520ff7f38deb3bbc47bef195d18989 v: v3

---
 [refs]                      | 2 +-
 trunk/include/linux/sched.h | 1 +
 trunk/kernel/exit.c         | 5 +++++
 trunk/kernel/sched.c        | 8 ++++++++
 4 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index d84bac85be38..bc017b9f9bad 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 5ac5c4d604bf894ef672a7971d03fefdc7ea7e49
+refs/heads/master: ad474caca3e2a0550b7ce0706527ad5ab389a4d4
diff --git a/trunk/include/linux/sched.h b/trunk/include/linux/sched.h
index 295b7c756ca6..644ffbda17ca 100644
--- a/trunk/include/linux/sched.h
+++ b/trunk/include/linux/sched.h
@@ -247,6 +247,7 @@ extern void init_idle(struct task_struct *idle, int cpu);
 extern void init_idle_bootup_task(struct task_struct *idle);
 
 extern int runqueue_is_locked(void);
+extern void task_rq_unlock_wait(struct task_struct *p);
 
 extern cpumask_t nohz_cpu_mask;
 #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ)
diff --git a/trunk/kernel/exit.c b/trunk/kernel/exit.c
index 80137a5d9467..ae2b92be5fae 100644
--- a/trunk/kernel/exit.c
+++ b/trunk/kernel/exit.c
@@ -141,6 +141,11 @@ static void __exit_signal(struct task_struct *tsk)
 	if (sig) {
 		flush_sigqueue(&sig->shared_pending);
 		taskstats_tgid_free(sig);
+		/*
+		 * Make sure ->signal can't go away under rq->lock,
+		 * see account_group_exec_runtime().
+		 */
+		task_rq_unlock_wait(tsk);
 		__cleanup_signal(sig);
 	}
 }
diff --git a/trunk/kernel/sched.c b/trunk/kernel/sched.c
index f3149244e324..50a21f964679 100644
--- a/trunk/kernel/sched.c
+++ b/trunk/kernel/sched.c
@@ -969,6 +969,14 @@ static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
 	}
 }
 
+void task_rq_unlock_wait(struct task_struct *p)
+{
+	struct rq *rq = task_rq(p);
+
+	smp_mb(); /* spin-unlock-wait is not a full memory barrier */
+	spin_unlock_wait(&rq->lock);
+}
+
 static void __task_rq_unlock(struct rq *rq)
 	__releases(rq->lock)
 {