From patchwork Sat Oct 28 12:58:22 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hou Tao X-Patchwork-Id: 10030987 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 77B486032C for ; Sat, 28 Oct 2017 12:54:15 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6AC362883B for ; Sat, 28 Oct 2017 12:54:15 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5FB1228ADF; Sat, 28 Oct 2017 12:54:15 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4CE9628ADE for ; Sat, 28 Oct 2017 12:54:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751345AbdJ1Mwh (ORCPT ); Sat, 28 Oct 2017 08:52:37 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:9536 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751156AbdJ1Mwc (ORCPT ); Sat, 28 Oct 2017 08:52:32 -0400 Received: from 172.30.72.59 (EHLO DGGEMS408-HUB.china.huawei.com) ([172.30.72.59]) by dggrg05-dlp.huawei.com (MOS 4.4.6-GA FastPath queued) with ESMTP id DKB13573; Sat, 28 Oct 2017 20:52:16 +0800 (CST) Received: from huawei.com (10.175.124.28) by DGGEMS408-HUB.china.huawei.com (10.3.19.208) with Microsoft SMTP Server id 14.3.361.1; Sat, 28 Oct 2017 20:52:13 +0800 From: Hou Tao To: CC: , , , , , Subject: [RFC][PATCH 3/8] epoll: remove file from tfile_check_list when releasing file Date: Sat, 28 Oct 2017 20:58:22 +0800 Message-ID: <1509195507-29037-4-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 X-Originating-IP: [10.175.124.28] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A090203.59F47D80.0073, 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: 9aed945cc579ad36002a71c745d737c2 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Before the removal of epmutex, the acquisition of epmutex in eventpoll_release_file() will prevent the freeing of file, so it's OK to iterate files in tfile_check_list. And now epmutex is removed, so when releasing file, we need to remove file from tfile_check_list to ensure the validity of file. Signed-off-by: Hou Tao --- fs/eventpoll.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 44ea587..998c635 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1029,6 +1029,18 @@ void eventpoll_release_file(struct file *file) ep_remove(ep, epi); mutex_unlock(&ep->mtx); } + + /* + * The file can not been added to tfile_check_list again, because + * (1) its refcnt has been zero, so ep_ctrl() can no longer get its reference + * (2) its related ep items have been removed, so ep_loop_check_proc() + * can not get the file by ep->rbr + */ + if (!list_empty_careful(&file->f_tfile_llink)) { + mutex_lock(&epmutex); + list_del_init(&file->f_tfile_llink); + mutex_unlock(&epmutex); + } } static int ep_alloc(struct eventpoll **pep)