From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A1770C169C4 for ; Sun, 3 Feb 2019 13:53:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6C612218D8 for ; Sun, 3 Feb 2019 13:53:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728843AbfBCNxr (ORCPT ); Sun, 3 Feb 2019 08:53:47 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:54090 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728448AbfBCNuG (ORCPT ); Sun, 3 Feb 2019 08:50:06 -0500 Received: from cable-78.29.236.164.coditel.net ([78.29.236.164] helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gqI9s-0003tl-4d; Sun, 03 Feb 2019 13:50:04 +0000 Received: from ben by deadeye with local (Exim 4.92-RC4) (envelope-from ) id 1gqI9o-0007Lk-DA; Sun, 03 Feb 2019 14:50:00 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Trond Myklebust" Date: Sun, 03 Feb 2019 14:45:08 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 252/305] SUNRPC: Fix a potential race in xprt_connect() In-Reply-To: X-SA-Exim-Connect-IP: 78.29.236.164 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.63-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Trond Myklebust commit 0a9a4304f3614e25d9de9b63502ca633c01c0d70 upstream. 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: Ben Hutchings --- net/sunrpc/xprt.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -721,8 +721,15 @@ 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); + } } }