From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754207Ab1CQMQ5 (ORCPT ); Thu, 17 Mar 2011 08:16:57 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:9482 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753846Ab1CQMQ4 (ORCPT ); Thu, 17 Mar 2011 08:16:56 -0400 Subject: [PATCH] RPC: killing RPC tasks races fixed To: Trond.Myklebust@netapp.com From: Stanislav Kinsbursky Cc: linux-nfs@vger.kernel.org, xemul@parallels.com, neilb@suse.de, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bfields@fieldses.org, davem@davemloft.net, skinsbursky@openvz.org Date: Thu, 17 Mar 2011 15:16:55 +0300 Message-ID: <20110317121638.15035.39410.stgit@localhost6.localdomain6> User-Agent: StGit/0.15 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org task->tk_waitqueue must be checked for NULL before trying to wake up task in rpc_killall_tasks() because it can be NULL. Here is an example: CPU 0 CPU 1 CPU 2 -------------------- --------------------- -------------------------- nfs4_run_open_task rpc_run_task rpc_execute rpc_set_active rpc_make_runnable (waiting) rpc_async_schedule nfs4_open_prepare nfs_wait_on_sequence nfs_umount_begin rpc_killall_tasks rpc_wake_up_task rpc_wake_up_queued_task spin_lock(tk_waitqueue == NULL) BUG() rpc_sleep_on spin_lock(&q->lock) __rpc_sleep_on task->tk_waitqueue = q Signed-off-by: Stanislav Kinsbursky --- net/sunrpc/clnt.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 57d344c..24039fe 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -436,7 +436,9 @@ void rpc_killall_tasks(struct rpc_clnt *clnt) if (!(rovr->tk_flags & RPC_TASK_KILLED)) { rovr->tk_flags |= RPC_TASK_KILLED; rpc_exit(rovr, -EIO); - rpc_wake_up_queued_task(rovr->tk_waitqueue, rovr); + if (rovr->tk_waitqueue) + rpc_wake_up_queued_task(rovr->tk_waitqueue, + rovr); } } spin_unlock(&clnt->cl_lock);