From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752594AbXLDJqA (ORCPT ); Tue, 4 Dec 2007 04:46:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752047AbXLDJpw (ORCPT ); Tue, 4 Dec 2007 04:45:52 -0500 Received: from smtp2.linux-foundation.org ([207.189.120.14]:57502 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751973AbXLDJpw (ORCPT ); Tue, 4 Dec 2007 04:45:52 -0500 Date: Tue, 4 Dec 2007 01:45:49 -0800 From: Andrew Morton To: Pavel Emelyanov Cc: ebiederm@xmission.com, linux-kernel@vger.kernel.org, devel@openvz.org Subject: Re: [PATCH 1/7][QUOTA] Move sysctl management code under ifdef CONFIG_SYSCTL Message-Id: <20071204014549.8fe47f7f.akpm@linux-foundation.org> In-Reply-To: <47551E79.6080802@openvz.org> References: <475008F5.3000506@openvz.org> <475009FA.20409@openvz.org> <20071203133844.40804dab.akpm@linux-foundation.org> <475516B6.5000504@openvz.org> <20071204012301.4349bbd0.akpm@linux-foundation.org> <47551E79.6080802@openvz.org> X-Mailer: Sylpheed 2.4.1 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 04 Dec 2007 12:31:37 +0300 Pavel Emelyanov wrote: > Andrew Morton wrote: > > On Tue, 04 Dec 2007 11:58:30 +0300 Pavel Emelyanov wrote: > > > >>>> +#ifdef CONFIG_SYSCTL > >>>> register_sysctl_table(sys_table); > >>>> +#endif > >>>> > >>>> dquot_cachep = kmem_cache_create("dquot", > >>>> sizeof(struct dquot), sizeof(unsigned long) * 4, > >>> We should avoid the ifdefs around the register_sysctl_table() call. > >>> > >>> At present the !CONFIG_SYSCTL implementation of register_sysctl_table() is > >>> a non-inlined NULL-returning stub. All we have to do is to inline that stub > >>> then these ifdefs can go away. > >> What if some code checks for the return value to be not-NULL? In case > >> CONFIG_SYSCTL=n this code will always think, that the registration failed. > > > > The stub function should return success? > > Well, I think yes. If some functionality is turned off, then the > caller should think that everything is going fine (or he should > explicitly removes the call to it with some other ifdef). > > At least this is true for stubs that return the error code, not > the pointer. E.g. copy_semundo() always returns success if SYSVIPC > is off, or namespaces cloning routines act in a similar way. > > Thus I though, that routines, that return pointers should better > report that everything is OK (somehow) to reduce the number of > "helpers" in the outer code. No? > Dunno. Returning NULL should be OK. If anyone is dereferenceing that pointer with CONFIG_SYSCTL=n then they might need some attention?