From mboxrd@z Thu Jan 1 00:00:00 1970 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=-16.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 6E627C07E99 for ; Fri, 9 Jul 2021 12:27:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 51D166124C for ; Fri, 9 Jul 2021 12:27:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231384AbhGIMaJ (ORCPT ); Fri, 9 Jul 2021 08:30:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60158 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231371AbhGIMaI (ORCPT ); Fri, 9 Jul 2021 08:30:08 -0400 Received: from mail-pf1-x432.google.com (mail-pf1-x432.google.com [IPv6:2607:f8b0:4864:20::432]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A6180C0613DD for ; Fri, 9 Jul 2021 05:27:23 -0700 (PDT) Received: by mail-pf1-x432.google.com with SMTP id b12so8573762pfv.6 for ; Fri, 09 Jul 2021 05:27:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=fE0Dne1h5bAxI4O1/CQzPMn/t0RrZprT0Cm6d5DM/Zs=; b=E5ff6SHHXOqKedBxsbjEoWoyB1JCax2IKfLx+Q7nq+RpHvUcgZdvB0FtgiI0gNpIbR 61F5C5weVZsQNmuN1nFAiiPKBztcykQfdAnktW0JyW7XKdTClGfoJE1RxclHW1NWU8Sv 98RT8gKPqv9CNMc80or06upJxbBmd7GT2If1dvdJgBpYVpbZbo1s5Dp5peEh6wRXI73W 2+MuIZYFNJlsraqeUzIsSzwdsC+97QKmQd702aM9nEzgPyg8C2oOveH9Bk4gUjBSN2rT t8hdHC7ZMoKgkc2lzVonXOg+QkTF7enyOKYFMuKTsfCtgqxOQGk+GITOcWz3Z/IYs9+a +JYg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=fE0Dne1h5bAxI4O1/CQzPMn/t0RrZprT0Cm6d5DM/Zs=; b=FzUUsrRl2UxTg7hkQj0HiVHWZrNlTufCJCp7lk19DJceJG5PQvk+rNlDxBmiHg2Tc+ reoc/fmozTgxQ1dysQZuITXtPhGWSSM3F6wrfGBbVyohWoRCi4CvDNrOVJCQJpNFsxRb d9ISuI4oORvZ4Vw/NO04MXWd5GKmMd1p6eN6/xsJ/Jmc6a+jqkx1eXc8kjnEaln8INYH PAwIQpGFr6VK5wkSuHJc1Cvlr04UKrCTJHVXG23TJuDE5W/LcgHu52GR5+I9Q961WDNs 37tNek7FjDncseT+cLWvpCDDRsnEO3VcerSonGFqMM/fcNHAtXyAx4DfRz7WNy5X1GyT AkRQ== X-Gm-Message-State: AOAM530Klqoa2LhORK/kX0Jrapt8d1o6p+hSKf1SvsPlWTrIu12SHgMs wW4/e5A3emy9t+/9qVNQ7TI= X-Google-Smtp-Source: ABdhPJwJFVIItO27Z7piUEFt7/ryxpcK40iEMKLc5/nm1ZwQBuLckO8JKCPt0xFyLv3V5B020gOo5g== X-Received: by 2002:a05:6a00:bd5:b029:328:92ef:d3d8 with SMTP id x21-20020a056a000bd5b029032892efd3d8mr4747415pfu.51.1625833643284; Fri, 09 Jul 2021 05:27:23 -0700 (PDT) Received: from localhost.localdomain (f.a4.5177.ip4.static.sl-reverse.com. [119.81.164.15]) by smtp.gmail.com with ESMTPSA id g7sm3885986pfm.5.2021.07.09.05.27.21 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 09 Jul 2021 05:27:23 -0700 (PDT) From: yaozhenguo To: axboe@kernel.dk, oleg@redhat.comm Cc: linux-kernel@vger.kernel.org, yaozhenguo@jd.com, yaozhenguo Subject: [PATCH] task_work: return -EBUSY when adding same work Date: Fri, 9 Jul 2021 20:27:12 +0800 Message-Id: <20210709122712.42844-1-yaozhenguo1@gmail.com> X-Mailer: git-send-email 2.32.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org when same work is added to task->task_works list one by one, the list becomes endless loop. So return -EBUSY when this situation happen. Signed-off-by: yaozhenguo --- kernel/task_work.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/task_work.c b/kernel/task_work.c index 1698fbe..5061ebf 100644 --- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -27,7 +27,7 @@ * list is LIFO. * * RETURNS: - * 0 if succeeds or -ESRCH. + * 0 if succeeds or -ESRCH, -EBUSY. */ int task_work_add(struct task_struct *task, struct callback_head *work, enum task_work_notify_mode notify) @@ -41,6 +41,8 @@ int task_work_add(struct task_struct *task, struct callback_head *work, head = READ_ONCE(task->task_works); if (unlikely(head == &work_exited)) return -ESRCH; + if (unlikely(head == work)) + return -EBUSY; work->next = head; } while (cmpxchg(&task->task_works, head, work) != head); -- 1.8.3.1