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=-2.4 required=3.0 tests=DKIM_SIGNED, MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID,URIBL_BLOCKED,USER_AGENT_MUTT 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 361A1C4321D for ; Tue, 21 Aug 2018 16:09:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E795520685 for ; Tue, 21 Aug 2018 16:09:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="SYCJamep" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E795520685 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728282AbeHUTaC (ORCPT ); Tue, 21 Aug 2018 15:30:02 -0400 Received: from mail-yb0-f193.google.com ([209.85.213.193]:43527 "EHLO mail-yb0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727484AbeHUTaC (ORCPT ); Tue, 21 Aug 2018 15:30:02 -0400 Received: by mail-yb0-f193.google.com with SMTP id k5-v6so3118001ybo.10; Tue, 21 Aug 2018 09:09:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=gI/qP9Vpnqz/vHqt9Lw9NT8dYlKXOkn3YNDTTsR5BNk=; b=SYCJamep34LLMkYLJwx5TFGOMvutkLKgb6hOxtJ8PjkBTZl/OKvzihJ11MdoYHWnb4 plVpZcOYjwH/8WEVAn0XbsR9QrmhxNV6zmA6xsKbspUgKprGrj5eh+A2ceQaDWjIL4ei Hi2KqfpQSlu4s2tLlawbrIaz0keZ5LiISc4zE7MAZaFWcTWw4Udn/dDpLT+xrAFZKtCf aj7byUNI9tj3Tt0QD0WO22Pw0p3bpG3DvcsY8Z5udEG8qyrmwaze3oyhQUE3xSHLmHIZ 1IpRoNqdiYuzNxTz/JG7hkgXCbNfsVBPzEzx7IsJY/ZqJ/OtkpiliSdRUuG5XZn3LcEw cFsg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=gI/qP9Vpnqz/vHqt9Lw9NT8dYlKXOkn3YNDTTsR5BNk=; b=j+2AD9ARyZ7C9lnDbQTb0zGkZTfa2C5di+mcHVsOTsqyPkVqTFn3Ex3u+5tKWnM7hX 1gkbajjVNyNCUy4X8hbydpW125Njbe5knsgy3hnMGRYQkyTkGJzOfV0eDhjnfpiOB17i 5vP187pYaAmOgzk0eGmL1kG2EPVxrZvKydTxCh1TcQJ1KKdNsxEa84fEZquZ4AFLSBBB 88Eq26uirWzHLkFP0jz4J3E4rK0dkrXeW/JiuZs6aBgdgIdR3XeNNEPuP3eFtYsVzVQk ToB2taaXG7pN4oI5d/30cpvnrFsk4NRzk2rTvjfH3s/CdvB2zwttuDBOhCkjCTqt+ad6 xp6A== X-Gm-Message-State: AOUpUlE9PDqFGyESe7Pz65aPIx5Hwce8YcsWxJXYEXzf5uQMJ2/ws4rY KBbiCByjh9oLUr63fyibYY4= X-Google-Smtp-Source: AA+uWPyAGSXN0GUkvVUhAwFpaJLNwqHmbb+cfTNjQu88EGfKTcp5QStsWU+D2Rwq32JW4u0zkDzjpA== X-Received: by 2002:a25:a28b:: with SMTP id c11-v6mr9616371ybi.478.1534867757129; Tue, 21 Aug 2018 09:09:17 -0700 (PDT) Received: from localhost ([2620:10d:c091:200::1:9c5d]) by smtp.gmail.com with ESMTPSA id n187-v6sm9559934ywn.76.2018.08.21.09.09.16 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 21 Aug 2018 09:09:16 -0700 (PDT) Date: Tue, 21 Aug 2018 09:09:14 -0700 From: Tejun Heo To: Johannes Berg Cc: Lai Jiangshan , linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, Johannes Berg Subject: Re: [PATCH 2/2] workqueue: create lockdep dependency in flush_work() Message-ID: <20180821160914.GQ3978217@devbig004.ftw2.facebook.com> References: <20180821120317.4115-1-johannes@sipsolutions.net> <20180821120317.4115-3-johannes@sipsolutions.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180821120317.4115-3-johannes@sipsolutions.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 21, 2018 at 02:03:17PM +0200, Johannes Berg wrote: > From: Johannes Berg > > In flush_work(), we need to create a lockdep dependency so that > the following scenario is appropriately tagged as a problem: > > work_function() > { > mutex_lock(&mutex); > ... > } > > other_function() > { > mutex_lock(&mutex); > flush_work(&work); // or cancel_work_sync(&work); > } > > This is a problem since the work might be running and be blocked > on trying to acquire the mutex. > > Signed-off-by: Johannes Berg This makes sense to me. Did you notice any extra lockdep warnings with this? Thanks. -- tejun