From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755041Ab3AXDkN (ORCPT ); Wed, 23 Jan 2013 22:40:13 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:44280 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754371Ab3AXD3z (ORCPT ); Wed, 23 Jan 2013 22:29:55 -0500 From: Herton Ronaldo Krzesinski To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Trond Myklebust , Herton Ronaldo Krzesinski Subject: [PATCH 36/74] SUNRPC: Ensure we release the socket write lock if the rpc_task exits early Date: Thu, 24 Jan 2013 01:26:48 -0200 Message-Id: <1358998046-613-37-git-send-email-herton.krzesinski@canonical.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1358998046-613-1-git-send-email-herton.krzesinski@canonical.com> References: <1358998046-613-1-git-send-email-herton.krzesinski@canonical.com> X-Extended-Stable: 3.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.5.7.4 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Trond Myklebust commit 87ed50036b866db2ec2ba16b2a7aec4a2b0b7c39 upstream. If the rpc_task exits while holding the socket write lock before it has allocated an rpc slot, then the usual mechanism for releasing the write lock in xprt_release() is defeated. The problem occurs if the call to xprt_lock_write() initially fails, so that the rpc_task is put on the xprt->sending wait queue. If the task exits after being assigned the lock by __xprt_lock_write_func, but before it has retried the call to xprt_lock_and_alloc_slot(), then it calls xprt_release() while holding the write lock, but will immediately exit due to the test for task->tk_rqstp != NULL. Reported-by: Chris Perl Signed-off-by: Trond Myklebust Signed-off-by: Herton Ronaldo Krzesinski --- net/sunrpc/sched.c | 3 +-- net/sunrpc/xprt.c | 12 ++++++++++-- 2 files changed, 11 insertions(+), 4 deletions(-) diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index fe2cf2f..85b9235 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -953,8 +953,7 @@ static void rpc_async_release(struct work_struct *work) static void rpc_release_resources_task(struct rpc_task *task) { - if (task->tk_rqstp) - xprt_release(task); + xprt_release(task); if (task->tk_msg.rpc_cred) { put_rpccred(task->tk_msg.rpc_cred); task->tk_msg.rpc_cred = NULL; diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index 2d5b811..6329ff3 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -1139,10 +1139,18 @@ static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt) void xprt_release(struct rpc_task *task) { struct rpc_xprt *xprt; - struct rpc_rqst *req; + struct rpc_rqst *req = task->tk_rqstp; - if (!(req = task->tk_rqstp)) + if (req == NULL) { + if (task->tk_client) { + rcu_read_lock(); + xprt = rcu_dereference(task->tk_client->cl_xprt); + if (xprt->snd_task == task) + xprt_release_write(xprt, task); + rcu_read_unlock(); + } return; + } xprt = req->rq_xprt; if (task->tk_ops->rpc_count_stats != NULL) -- 1.7.9.5