Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757225AbYJQPVe (ORCPT ); Fri, 17 Oct 2008 11:21:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754938AbYJQPVY (ORCPT ); Fri, 17 Oct 2008 11:21:24 -0400 Received: from ns1.suse.de ([195.135.220.2]:46616 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755092AbYJQPVX (ORCPT ); Fri, 17 Oct 2008 11:21:23 -0400 Date: Fri, 17 Oct 2008 17:21:21 +0200 Message-ID: From: Takashi Iwai To: Mark Brown Cc: Zhaolei , alsa-devel@alsa-project.org, "linux-kernel@vger.kernel.org" , lrg@slimlogic.co.uk Subject: Re: [alsa-devel] [PATCH] Fix debugfs_create_dir's error checking method for sound/soc/ In-Reply-To: <20081017132340.GF2546@sirena.org.uk> References: <48F88D77.2080106@cn.fujitsu.com> <20081017132340.GF2546@sirena.org.uk> User-Agent: Wanderlust/2.12.0 (Your Wildest Dreams) SEMI/1.14.6 (Maruoka) FLIM/1.14.7 (=?ISO-8859-4?Q?Sanj=F2?=) APEL/10.6 Emacs/22.3 (x86_64-suse-linux-gnu) MULE/5.0 (SAKAKI) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1365 Lines: 39 At Fri, 17 Oct 2008 14:23:42 +0100, Mark Brown wrote: > > On Fri, Oct 17, 2008 at 09:04:55PM +0800, Zhaolei wrote: > > > debugfs_create_dir() returns NULL if an error occurs, returns -ENODEV > > when debugfs is not enabled in the kernel. > > ... > > > asoc_debugfs = debugfs_create_dir("asoc", NULL); > > - if (!IS_ERR(asoc_debugfs)) > > + if (!IS_ERR(asoc_debugfs) && asoc_debugfs) > > debugfs_create_u32("dapm_pop_time", 0744, asoc_debugfs, > > &pop_time); > > Hrmpf. This looks like something that should be fixed in debugfs - > using both error reporting strategies is rather unhelpful and we're > actually loosing information in the case where debugfs is built. I'll > send a patch and see what people thing. This looks like a design. In linux/debugfs.h: /* * We do not return NULL from these functions if CONFIG_DEBUG_FS is not enabled * so users have a chance to detect if there was a real error or not. We don't * want to duplicate the design decision mistakes of procfs and devfs again. */ Though, I agree that the detailed error information is lost by returning NULL... Takashi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/