From patchwork Tue Mar 9 03:06:02 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zheng Yejian X-Patchwork-Id: 396591 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham 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 3DED8C433E0 for ; Tue, 9 Mar 2021 03:00:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 01BA56528D for ; Tue, 9 Mar 2021 02:59:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229904AbhCIC70 (ORCPT ); Mon, 8 Mar 2021 21:59:26 -0500 Received: from szxga07-in.huawei.com ([45.249.212.35]:13873 "EHLO szxga07-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229599AbhCIC7Q (ORCPT ); Mon, 8 Mar 2021 21:59:16 -0500 Received: from DGGEMS410-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga07-in.huawei.com (SkyGuard) with ESMTP id 4DvfyJ6HPqz8vQn; Tue, 9 Mar 2021 10:57:28 +0800 (CST) Received: from code-website.localdomain (10.175.127.227) by DGGEMS410-HUB.china.huawei.com (10.3.19.210) with Microsoft SMTP Server id 14.3.498.0; Tue, 9 Mar 2021 10:59:04 +0800 From: Zheng Yejian To: , , , CC: , , , , Subject: [PATCH 4.4 0/3] Backport patch series to update Futex from 4.9 Date: Tue, 9 Mar 2021 11:06:02 +0800 Message-ID: <20210309030605.3295183-1-zhengyejian1@huawei.com> X-Mailer: git-send-email 2.25.4 MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org Lee sent a patchset to update Futex for 4.9, see https://www.spinics.net/lists/stable/msg443081.html, Then Xiaoming sent a follow-up patch for it, see https://lore.kernel.org/lkml/20210225093120.GD641347@dell/. These patchsets may also resolve following issues in 4.4.260 which have been reported in 4.9, see https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/?h=linux-4.4.y&id=319f66f08de1083c1fe271261665c209009dd65a > /* > * The task is on the way out. When the futex state is > * FUTEX_STATE_DEAD, we know that the task has finished > * the cleanup: > */ > int ret = (p->futex_state = FUTEX_STATE_DEAD) ? -ESRCH : -EAGAIN; Here may be: int ret = (p->futex_state == FUTEX_STATE_DEAD) ? -ESRCH : -EAGAIN; > raw_spin_unlock_irq(&p->pi_lock); > /* > * If the owner task is between FUTEX_STATE_EXITING and > * FUTEX_STATE_DEAD then store the task pointer and keep > * the reference on the task struct. The calling code will > * drop all locks, wait for the task to reach > * FUTEX_STATE_DEAD and then drop the refcount. This is > * required to prevent a live lock when the current task > * preempted the exiting task between the two states. > */ > if (ret == -EBUSY) And here, the variable "ret" may only be "-ESRCH" or "-EAGAIN", but not "-EBUSY". > *exiting = p; > else > put_task_struct(p); Since 074e7d515783 ("futex: Ensure the correct return value from futex_lock_pi()") has been merged in 4.4.260, I send the remain 3 patches. Peter Zijlstra (1): futex: Change locking rules Thomas Gleixner (2): futex: Cure exit race futex: fix dead code in attach_to_pi_owner() kernel/futex.c | 209 +++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 177 insertions(+), 32 deletions(-)