Return-path: Received: from charlotte.tuxdriver.com ([70.61.120.58]:41535 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753376AbZFETPb (ORCPT ); Fri, 5 Jun 2009 15:15:31 -0400 Date: Fri, 5 Jun 2009 15:08:56 -0400 From: "John W. Linville" To: castet.matthieu@free.fr Cc: Michael Buesch , linux-wireless@vger.kernel.org, bcm43xx-dev@lists.berlios.de Subject: Re: [PATCH] b43: Fix possible unaligned u32 access Message-ID: <20090605190855.GC7361@tuxdriver.com> References: <200906042318.33895.mb@bu3sch.de> <20090605122503.GA2791@tuxdriver.com> <1244214237.4a2933dda6634@imp.free.fr> <20090605185307.GB7361@tuxdriver.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20090605185307.GB7361@tuxdriver.com> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Fri, Jun 05, 2009 at 02:53:07PM -0400, John W. Linville wrote: > On Fri, Jun 05, 2009 at 05:03:57PM +0200, castet.matthieu@free.fr wrote: > > Quoting "John W. Linville" : > > > > > On Thu, Jun 04, 2009 at 11:18:33PM +0200, Michael Buesch wrote: > > > > From: Matthieu CASTET > > > > > > > > Fix possible unaligned u32 access in b43_generate_plcp_hdr(). > > > > Unaligned data is read/write with a u32 pointer instead of using the > > > > packed structure. Some versions of gcc ignore the "packed" attribute, if > > > the > > > > structure element is accessed through a local pointer. > > > > > > > > Signed-off-by: Matthieu CASTET > > > > Signed-off-by: Michael Buesch > > > > > > That seems pretty brain-dead...can you cite a source for this > > > information? > > The test I did with the attached test case in the first post. > > Link? > > > I don't see why gcc should propagate packed structure info to assignment. > > That will be impossible to handle (think of passing it to function parameter). > > Perhaps this is obvious to you, but it isn't to me. OK, I got an explanation from Kyle McMartin that I grok... > > > > > The patch seems like a no-op... > > At least the code produced on mips is different. > > Then why aren't you trying to get the mips gcc guys to fix it? Still worth wondering...anyway, the patch is fine -- I just didn't grok the explanation. John -- John W. Linville Someday the world will need a hero, and you linville@tuxdriver.com might be all we have. Be ready.