From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759248AbYAPHe3 (ORCPT ); Wed, 16 Jan 2008 02:34:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753582AbYAPHeV (ORCPT ); Wed, 16 Jan 2008 02:34:21 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:40318 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752753AbYAPHeU (ORCPT ); Wed, 16 Jan 2008 02:34:20 -0500 Date: Wed, 16 Jan 2008 08:33:22 +0100 From: Ingo Molnar To: venkatesh.pallipadi@intel.com Cc: ak@muc.de, ebiederm@xmission.com, rdreier@cisco.com, torvalds@linux-foundation.org, gregkh@suse.de, airlied@skynet.ie, davej@redhat.com, tglx@linutronix.de, hpa@zytor.com, akpm@linux-foundation.org, arjan@infradead.org, jesse.barnes@intel.com, davem@davemloft.net, linux-kernel@vger.kernel.org, Suresh Siddha Subject: Re: [patch 4/4] x86: PAT followup - use ioremap for devmem read of reserved regions Message-ID: <20080116073322.GE30950@elte.hu> References: <20080116023955.597433000@intel.com> <20080116024112.291093000@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080116024112.291093000@intel.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * venkatesh.pallipadi@intel.com wrote: > --- linux-2.6.git.orig/drivers/char/mem.c 2008-01-15 10:05:13.000000000 -0800 > +++ linux-2.6.git/drivers/char/mem.c 2008-01-15 10:05:51.000000000 -0800 > @@ -127,9 +127,14 @@ > * by the kernel or data corruption may occur > */ > ptr = xlate_dev_mem_ptr(p); > + if (!ptr) > + return -EFAULT; > > if (copy_to_user(buf, ptr, sz)) > return -EFAULT; > + > + unxlate_dev_mem_ptr(p, ptr); sidenote: drivers/char/mem.c has no locking here, are you sure it's safe to create a possibly large number of aliases here? At least on 32-bit it could deplete the vmalloc area. (where all ioremaps go) since /dev/mem access is strongly discouraged anyway (except perhaps for debugging purposes), wouldnt it be safer to stick a mutex around these areas? Ingo