[3.16.y-ckt stable] Patch "net: pktgen: fix race between pktgen_thread_worker() and kthread_stop()" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    net: pktgen: fix race between pktgen_thread_worker() and kthread_stop()

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt17.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From f99d8ce5b9d92ab1e7a4e9a2dc24076f94df4e52 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg at redhat.com>
Date: Wed, 8 Jul 2015 21:42:11 +0200
Subject: net: pktgen: fix race between pktgen_thread_worker() and
 kthread_stop()

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 at redhat.com>
Reported-by: Jan Stancek <jstancek at redhat.com>
Reported-by: Marcelo Leitner <mleitner at redhat.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.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);