From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757293Ab1ERQIO (ORCPT ); Wed, 18 May 2011 12:08:14 -0400 Received: from mail-bw0-f46.google.com ([209.85.214.46]:55560 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757122Ab1ERQIM convert rfc822-to-8bit (ORCPT ); Wed, 18 May 2011 12:08:12 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=from:to:subject:date:user-agent:cc:references:in-reply-to :mime-version:content-type:content-transfer-encoding:message-id; b=Qy9P1SwGAPCNOUN9yzR/GPF7BOGwC7qfcE3ppty2H3RwurA/0bS7FUmcdHERQVXXjV mLX6Hvf+GXYfna6pRCayi5UjfeZZdpcTcn8H04sn3I319xGLxSlWprxdP2JKtym6zVu3 yGRm8AqAKDoJuYPe5cnhYf4PVW79rJ1jkdFy4= From: Christian Lamparter To: =?iso-8859-1?q?=C9ric_Piel?= Subject: Re: [RFC v2] lis3lv02d: avoid divide by zero due to unchecked register read Date: Wed, 18 May 2011 18:03:08 +0200 User-Agent: KMail/1.13.5 (Linux/2.6.39-rc7-wl+; KDE/4.4.5; x86_64; ; ) Cc: linux-kernel@vger.kernel.org References: <201105160046.31019.chunkeey@googlemail.com> <201105181747.12356.chunkeey@googlemail.com> <4DD3EC22.7060907@tremplin-utc.net> In-Reply-To: <4DD3EC22.7060907@tremplin-utc.net> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Message-Id: <201105181803.08972.chunkeey@googlemail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 18 May 2011 17:56:18 Éric Piel wrote: > Op 18-05-11 17:47, Christian Lamparter schreef: > > On Tuesday 17 May 2011 23:46:00 Éric Piel wrote: > >> Op 16-05-11 23:36, Christian Lamparter schreef: > >>> On Monday 16 May 2011 13:16:46 Éric Piel wrote: > >>> Do you know how "volatile" this data rate is? If it never changes > >>> [at least it doesn't here?] then why not read it once in init_device > >>> and store it in the device context? > >> It is not normally changing, normally it is set just at init/unsuspend > >> (where the bios can also interfere sometimes) and when the user changes > >> it. > > Uh, "bios can also interfere"... this sounds very bad. At least for > > my x41t the bios doesn't care about hdaps once the OS is running. > > > >> So definitely within the same function it's not going to suddenly > >> change. > > a SMM can happen at any time and if a faulty BIOS [likely, since I got > > a new laptop] is what caused the crash, I wouldn't bet on "const within > > a function context". > Yes, at least on the HP laptop I have the bios enjoys re-initialising > the hardware at some default value whenever suspend/resume happens. > > >> We could avoid calculating/checking it twice in > >> lis3lv02d_selftest(). Care to do a third version with this little clean up? > > I have my doubts, but ok if you say so... Just one thing: need to do some Q&A > > on the code above, I haven't tested it extensively yet. > I didn't know about the SMM... well, then let's keep the code as is. > > I'll try to test it on my laptop in the coming days. On which hardware > have you tested it? I've a dv6-6003eg, it's fairly new. Regards, Chr