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[68.40.195.73]) by smtp.gmail.com with ESMTPSA id p19sm2376777itp.13.2018.12.02.06.43.29 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sun, 02 Dec 2018 06:43:30 -0800 (PST) From: Trond Myklebust X-Google-Original-From: Trond Myklebust To: Chuck Lever Cc: linux-nfs@vger.kernel.org Subject: [PATCH] SUNRPC: Fix a potential race in xprt_connect() Date: Sun, 2 Dec 2018 09:42:23 -0500 Message-Id: <20181202144223.42562-1-trond.myklebust@hammerspace.com> X-Mailer: git-send-email 2.19.2 MIME-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 --- 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 122c91c28e7c..ce927002862a 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -826,8 +826,15 @@ 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); }