linux-kernel - [PATCH 3.2 096/107] net: pktgen: fix race between pktgen_thread_worker() and kthread

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Message-ID: <lsq.1444349548.442105790@decadent.org.uk>
Date:	Fri, 09 Oct 2015 01:12:28 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Oleg Nesterov" <oleg@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	"Marcelo Leitner" <mleitner@...hat.com>,
	"Jan Stancek" <jstancek@...hat.com>
Subject: [PATCH 3.2 096/107] net: pktgen: fix race between pktgen_thread_worker()
  and kthread_stop()

3.2.72-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Oleg Nesterov <oleg@...hat.com>

[ Upstream commit fecdf8be2d91e04b0a9a4f79ff06499a36f5d14f ]

pktgen_thread_worker() is obviously racy, kthread_stop() can come
between the kthread_should_stop() check and set_current_state().

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Reported-by: Jan Stancek <jstancek@...hat.com>
Reported-by: Marcelo Leitner <mleitner@...hat.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/core/pktgen.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -3481,8 +3481,10 @@ static int pktgen_thread_worker(void *ar
 	pktgen_rem_thread(t);
 
 	/* Wait for kthread_stop */
-	while (!kthread_should_stop()) {
+	for (;;) {
 		set_current_state(TASK_INTERRUPTIBLE);
+		if (kthread_should_stop())
+			break;
 		schedule();
 	}
 	__set_current_state(TASK_RUNNING);

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