Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754652AbZGKL6T (ORCPT ); Sat, 11 Jul 2009 07:58:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752888AbZGKL6K (ORCPT ); Sat, 11 Jul 2009 07:58:10 -0400 Received: from mgw1.diku.dk ([130.225.96.91]:41167 "EHLO mgw1.diku.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752697AbZGKL6J (ORCPT ); Sat, 11 Jul 2009 07:58:09 -0400 Date: Sat, 11 Jul 2009 13:58:05 +0200 (CEST) From: Julia Lawall To: Jiri Slaby Cc: Jaswinder Singh Rajput , gregkh@suse.de, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: Re: [PATCH 5/5] staging/otus: Move a dereference below a NULL test In-Reply-To: Message-ID: References: <4A584A94.5010105@gmail.com> <1247307444.3032.2.camel@hpdv5.satnam> <4A587245.1080304@gmail.com> MIME-Version: 1.0 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: 1368 Lines: 40 On Sat, 11 Jul 2009, Julia Lawall wrote: > On Sat, 11 Jul 2009, Jiri Slaby wrote: > > > On 07/11/2009 12:17 PM, Jaswinder Singh Rajput wrote: > > > On Sat, 2009-07-11 at 10:17 +0200, Jiri Slaby wrote: > > >> On 07/11/2009 09:51 AM, Julia Lawall wrote: > > >>> --- a/drivers/staging/otus/wwrap.c > > >>> +++ b/drivers/staging/otus/wwrap.c > > >>> @@ -1016,12 +1016,13 @@ void kevent(struct work_struct *work) > > >>> { > > >>> struct usbdrv_private *macp = > > >>> container_of(work, struct usbdrv_private, kevent); > > >>> - zdev_t *dev = macp->device; > > >>> + zdev_t *dev; > > >>> > > >>> if (macp == NULL) > > >>> { > > >>> return; > > >>> } > > >> > > >> The test is rather useless here. > > >> > > > > > > Why useless, it should be non-null before setting to dev. > > > > Even if work was NULL, macp won't be NULL. > > work could be a small negative number such that calling container_of would > return 0. On the other hand, that does not seem to be possible in this case, since work is passed through INIT_WORK, which dereferences the work value. julia -- 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/