linux-kernel - [PATCH 3.16.y-ckt 066/130] net: pktgen: fix race between pktgen_thread_worker() and kthread

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Date:	Fri,  4 Sep 2015 14:07:34 +0100
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Oleg Nesterov <oleg@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 066/130] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop()

3.16.7-ckt17 -stable review patch.  If anyone has any objections, please let me know.

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

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

commit fecdf8be2d91e04b0a9a4f79ff06499a36f5d14f upstream.

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: Luis Henriques <luis.henriques@...onical.com>
---
 net/core/pktgen.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 0e5719c20d61..0234ae038a62 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -3470,8 +3470,10 @@ static int pktgen_thread_worker(void *arg)
 	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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