linux-kernel - [PATCH 1/2] net: pktgen: fix race between pktgen_thread_worker() and kthread

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Date:	Wed, 8 Jul 2015 21:42:11 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Alexei Starovoitov <ast@...mgrid.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>
Cc:	Jan Stancek <jstancek@...hat.com>,
	Marcelo Leitner <mleitner@...hat.com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] net: pktgen: fix race between pktgen_thread_worker()
	and kthread_stop()

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>
---
 net/core/pktgen.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 508155b..043ea18 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -3490,8 +3490,10 @@ 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);
-- 
1.5.5.1

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