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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 25D8CC606BD for ; Mon, 8 Jul 2019 17:31:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EE0A4216FD for ; Mon, 8 Jul 2019 17:31:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562607102; bh=GDXQTiVeUiU/VwsdCmMiL7pxP6SiviFJVgivXw6p7T0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=sMq+r41WpEQ0DroUdesTYBhi1w5AnZCaAJKjQzhRLcm0lMQlYBGqx4890R4J4oKEc wI9zrU7I3dfxDfj+6o8q7IkQQCqF8XO0u+WWa41mw1P0NzK7IibLlvcVzJfwS28mtv Hj0vRK5KzYBPjXT8ODLSMHL3uaXDZ9waERyKrtSg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390207AbfGHRbk (ORCPT ); Mon, 8 Jul 2019 13:31:40 -0400 Received: from mail-qt1-f193.google.com ([209.85.160.193]:36013 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726997AbfGHRbk (ORCPT ); Mon, 8 Jul 2019 13:31:40 -0400 Received: by mail-qt1-f193.google.com with SMTP id z4so15385399qtc.3; Mon, 08 Jul 2019 10:31:39 -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=F3Z8ODmIuThf6qIMsRJ9IwagYSAnPtGl9RN+7VHHChg=; b=aqE1xvZMtT7tlMKN0uI2aPhS+B7q7NPQx57ZzTXE3rm2BGvJMUQYHZdGbsSR+ZNHfg KfCyif2Z5T+CAzVEI8+uNEiuZ86jaLvvcnbumD1DftZwskChw61iCaejgttVDYeo+puX EMcYe4mqQRkut1balpM3jphqF+6LvTpJVgsDGjeKNcaL2HrtEEceP6faQACtVF2GbCnH EnfW9OChjLrUTnLaic14bALWa2BZWvwWjb4HbOhssw6ZZDbanIOucVyKb3DXFQID3zzN 6PaxqH4Gy69wl4Cd+/ST6a+M1Yks+kZdteW72v8EtAfrgEC6A0/zqxo7tvMMEc0VlKUl /AcA== 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=F3Z8ODmIuThf6qIMsRJ9IwagYSAnPtGl9RN+7VHHChg=; b=BVMfdo+CNJi8nbWz7KKml47a5Goq8IzdzN0kmr9EBWQqncPfGlMzMqYUowBqKdGVeB 8qdt6Nv3z5pXjJ6szNvoLpLjfjntkeIHN0cL1sAfyrHjvgNFHfpLdXJbNN8mI0xIrz+O aRJ1MnkGgFn6Spd4pH1LFcH8ipprfkPUprraD3Nvpkr1XLOu3YFbIJla7NWEIlFA5RRd XN2B8/PvPhBU+LzACo3M7ruKrnk78u5CC7xqfIoHBCcyaJKZzvjv2IL+6fcxtfvUse11 5VqHPUqaRUbuOIHDSzp9LZ1KfAtJJ11rJDqgbNu57uh6IEdIdA/vZPbjYkrCzVJQ33mt 1cIA== X-Gm-Message-State: APjAAAU9IjvhyNawQP2RDl2yx19ZZI1iChyKlUqO6Z5IsyuoFh1h2KBO oTn1wYTf1WuRwKBNnJXS8Ro= X-Google-Smtp-Source: APXvYqzGrhEv1gxKVd1/9J9mYvxXMWJHhzWdHoqmqPs9JYDKKxlkOivbY+dTn6S37VhKMXYfjeiwoA== X-Received: by 2002:aed:2d67:: with SMTP id h94mr10495706qtd.154.1562607099035; Mon, 08 Jul 2019 10:31:39 -0700 (PDT) Received: from localhost ([2620:10d:c091:500::2:fa50]) by smtp.gmail.com with ESMTPSA id m44sm8984785qtm.54.2019.07.08.10.31.38 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 08 Jul 2019 10:31:38 -0700 (PDT) Date: Mon, 8 Jul 2019 10:31:37 -0700 From: Tejun Heo To: Roman Gushchin Cc: Peng Wang , "lizefan@huawei.com" , "hannes@cmpxchg.org" , "cgroups@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] cgroup: minor tweak for logic to get cgroup css Message-ID: <20190708173137.GH657710@devbig004.ftw2.facebook.com> References: <20190703020749.22988-1-rocking@whu.edu.cn> <20190708164243.GE657710@devbig004.ftw2.facebook.com> <20190708172944.GA24662@tower.DHCP.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190708172944.GA24662@tower.DHCP.thefacebook.com> 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 Mon, Jul 08, 2019 at 05:29:49PM +0000, Roman Gushchin wrote: > On Mon, Jul 08, 2019 at 09:42:43AM -0700, Tejun Heo wrote: > > On Wed, Jul 03, 2019 at 10:07:49AM +0800, Peng Wang wrote: > > > We could only handle the case that css exists > > > and css_try_get_online() fails. > > > > As css_tryget_online() can't handle NULL input, this is a bug fix. > > Can you please clarify that in the description? > > - if (!css || !css_tryget_online(css)) > + if (css && !css_tryget_online(css)) > > If css == NULL, !css is true, and the second part of the || statement > will not be evaluated. So it's not a bug fix. Ah right, it's just confusing. Will apply after the merge window. Thanks. -- tejun