Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964843AbXBUEG5 (ORCPT ); Tue, 20 Feb 2007 23:06:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965113AbXBUEG5 (ORCPT ); Tue, 20 Feb 2007 23:06:57 -0500 Received: from cantor2.suse.de ([195.135.220.15]:39566 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964843AbXBUEG4 (ORCPT ); Tue, 20 Feb 2007 23:06:56 -0500 Date: Tue, 20 Feb 2007 20:05:26 -0800 From: Greg KH To: Jan Engelhardt Cc: "Serge E. Hallyn" , Linux Kernel Mailing List Subject: Re: securityfs_create_dir strange comment Message-ID: <20070221040526.GA8207@kroah.com> References: <20070220211849.GA3416@vino.hallyn.com> <20070220222652.GB21696@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2102 Lines: 65 On Wed, Feb 21, 2007 at 12:45:40AM +0100, Jan Engelhardt wrote: > > On Feb 20 2007 14:26, Greg KH wrote: > >On Tue, Feb 20, 2007 at 03:18:49PM -0600, Serge E. Hallyn wrote: > >> Quoting Jan Engelhardt (jengelh@linux01.gwdg.de): > >> > Hello list, > >> > > >> > > >> > in security/inode.c, the comment for securityfs_create_dir() reads: > >> > > >> > If securityfs is not enabled in the kernel, the value -ENODEV > >> > will be returned. It is not wise to check for this value, but > >> > rather, check for NULL or !NULL instead as to eliminate the need > >> > for #ifdef in the calling code. > >> > > >> > What is the actual callee that can return NULL - and what should > >> > module_init() of a module return when securityfs_create_dir() returns > >> > NULL? > >> > >> Hmm, this came from GregKH. It does seem based on the code that > >> checking for -ENODEV is necessary, so I don't understand the comment. > > > >If securityfs_create_dir() returns NULL, then something bad happened and > >your code needs to properly recover from it. > > > >Other than that, I don't understand the issue here. > > Consider: > > static __init int mymodule_init(void) > { > struct dentry *de; > de = securityfs_create_dir("foobar", NULL); > > /* case 1 */ > if(IS_ERR(de)) > return PTR_ERR(de); > > /* case 2 */ > if(de == NULL) > return WHAT_HERE; /* -EIO? */ > } > > There are two error cases. One: when the function gives us an error code. > Two: When it returns NULL, without an error code. This looks bogus to me. > What error is it, when there is no error? - And what should I return to > modprobe in that case? Try this instead: if (!de) return -ENOMEM; if ((IS_ERR(de)) && (PTR_ERR(de) != -ENODEV)) return PTR_ERR(de); return 0; That should cover everything properly, right? thanks, greg k-h - 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/