From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E32D92C1AC; Mon, 26 Aug 2024 18:35:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724697305; cv=none; b=A3oc1UkJFLAjwa/cPgl4lkwTeeRiTghvEQcDUvOP+jyChq0Xsb06s27P1PhAUDhU5LhKYi6BMZVEjG/wyYYsVylNVsoraYjF6sg8owMhnY+60vN9SDgQirhVSJaIB1flYCgI+62oLqE+W0PzBmn/KGeLmuv582+8qz9sOSO8wMo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724697305; c=relaxed/simple; bh=WJUAZ2Dnc20rY85yKNE4tfrmUEmCUGOXJQaQKBPAr9E=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QPOUZJTjANCej56hPA9IceaD5QyJKDsn3DdIFtg7FrSb99w+UcXVl1aSvHVNph2Nvmh6ioLs8zrUdFszb/e13TNgMbSsnmRAVApaeoUyyiwH0/EklB9yifBZPu6l2BaBw8/5g1QIDrnAAfe2CQwSr0/uF2WGztE8Mx0qh+0br6g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=s9kNKGik; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="s9kNKGik" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4ED00C4DDF5; Mon, 26 Aug 2024 18:35:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724697304; bh=WJUAZ2Dnc20rY85yKNE4tfrmUEmCUGOXJQaQKBPAr9E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=s9kNKGikqxa2n8dwiS0KYPv3mxnWfzvEtamLt2bCcvBMrVu0riREh5f9h7nO+MnOy EgJp6E6VI9dLYmWYOYwv1fx7J23oOqWmFbbG81eMF5JCe56UUH18cmd3e/pKPkD+zI kfYj0NE5LJ79JFD63oED2A8g32ucuPF6imZ57daUJJf8I/OKzeL+FNCOaKw9lDBr6b IJfRdLn/p4mgr0e4/toMcTlfJodHPAi/bKVnD0yXH/wa9hAo+FFWrIElsY33vmbJi7 +Hzzp60KT6vyImJDzxyLFx2o8Sq6a8Hnf3EU/Cz9hPNropubo5BYFDwdG9cr6dMvPL ediOM5/42em0A== Date: Mon, 26 Aug 2024 08:35:03 -1000 From: Tejun Heo To: Michal =?iso-8859-1?Q?Koutn=FD?= Cc: void@manifault.com, peterz@infradead.org, mingo@redhat.com, cgroups@vger.kernel.org, lizefan.x@bytedance.com, hannes@cmpxchg.org, kernel-team@meta.com, linux-kernel@vger.kernel.org, David Vernet , Josh Don , Hao Luo , Barret Rhoden Subject: Re: [PATCH 1/7] cgroup: Implement cgroup_show_cftypes() Message-ID: References: <20240808002550.731248-1-tj@kernel.org> <20240808002550.731248-2-tj@kernel.org> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Hello, Michal. On Tue, Aug 20, 2024 at 04:38:40PM +0200, Michal Koutný wrote: > On Wed, Aug 07, 2024 at 02:25:23PM GMT, Tejun Heo wrote: > > +void cgroup_show_cftype(struct cftype *cft, bool show) > > +{ > > + struct cgroup_subsys *ss = cft->ss; > > + struct cgroup *root = ss ? &ss->root->cgrp : &cgrp_dfl_root.cgrp; > > Strictly speaking, this (v1) cgroup_root dereference should be guarded > with cgroup_mutex too (should be the root destroy concurrently). Ah, right. I think I might just drop this patch. Hiding and showing the interface files dynamically doesn't seem to work that well in practive (ie. it causes more production problems than it solves). Something a bit more boring like triggering a warning when a unimplemented feature is used is probably better here. Thanks. -- tejun