From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751557AbdJ1Mwr (ORCPT ); Sat, 28 Oct 2017 08:52:47 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:9466 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751283AbdJ1Mwc (ORCPT ); Sat, 28 Oct 2017 08:52:32 -0400 From: Hou Tao To: CC: , , , , , Subject: [RFC][PATCH 8/8] epoll: protect the iteration of ep->rbr by ep->mtx in ep_free() Date: Sat, 28 Oct 2017 20:58:27 +0800 Message-ID: <1509195507-29037-9-git-send-email-houtao1@huawei.com> X-Mailer: git-send-email 2.7.5 In-Reply-To: <1509195507-29037-1-git-send-email-houtao1@huawei.com> References: <1509195507-29037-1-git-send-email-houtao1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.175.124.28] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A090204.59F47D84.0066,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 600dc33d7dab2bfca1e7903193844e69 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When ep_free() iterates the epi in ep->rbr, the epi may be removed by eventpoll_release_file(). To protect again the case, acquiring ep->mtx before the iteration of ep->rbr. Signed-off-by: Hou Tao --- fs/eventpoll.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index cd7a9f4..7618fb5 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -870,6 +870,7 @@ static void ep_free(struct eventpoll *ep) /* * Walks through the whole tree by unregistering poll callbacks. */ + mutex_lock(&ep->mtx); for (rbp = rb_first_cached(&ep->rbr); rbp; rbp = rb_next(rbp)) { epi = rb_entry(rbp, struct epitem, rbn); @@ -885,7 +886,6 @@ static void ep_free(struct eventpoll *ep) * We do not need to lock ep->mtx, either, we only do it to prevent * a lockdep warning. */ - mutex_lock(&ep->mtx); while ((rbp = rb_first_cached(&ep->rbr)) != NULL) { epi = rb_entry(rbp, struct epitem, rbn); ep_remove(ep, epi); -- 2.7.5