From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: [PATCH AUTOSEL 4.9 10/34] SUNRPC: Fix a potential race in xprt_connect() Date: Wed, 12 Dec 2018 23:31:36 -0500 Message-ID: <20181213043200.76295-10-sashal@kernel.org> References: <20181213043200.76295-1-sashal@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Cc: Trond Myklebust , Sasha Levin , linux-nfs@vger.kernel.org, netdev@vger.kernel.org To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Return-path: In-Reply-To: <20181213043200.76295-1-sashal@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Trond Myklebust [ Upstream commit 0a9a4304f3614e25d9de9b63502ca633c01c0d70 ] If an asynchronous connection attempt completes while another task is in xprt_connect(), then the call to rpc_sleep_on() could end up racing with the call to xprt_wake_pending_tasks(). So add a second test of the connection state after we've put the task to sleep and set the XPRT_CONNECTING flag, when we know that there can be no asynchronous connection attempts still in progress. Fixes: 0b9e79431377d ("SUNRPC: Move the test for XPRT_CONNECTING into...") Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin --- net/sunrpc/xprt.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index 685e6d225414..1a8df242d26a 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -778,8 +778,15 @@ void xprt_connect(struct rpc_task *task) return; if (xprt_test_and_set_connecting(xprt)) return; - xprt->stat.connect_start = jiffies; - xprt->ops->connect(xprt, task); + /* Race breaker */ + if (!xprt_connected(xprt)) { + xprt->stat.connect_start = jiffies; + xprt->ops->connect(xprt, task); + } else { + xprt_clear_connecting(xprt); + task->tk_status = 0; + rpc_wake_up_queued_task(&xprt->pending, task); + } } xprt_release_write(xprt, task); } -- 2.19.1