From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756308Ab0JALHO (ORCPT ); Fri, 1 Oct 2010 07:07:14 -0400 Received: from smtp.nokia.com ([192.100.122.233]:53021 "EHLO mgw-mx06.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754587Ab0JALHM (ORCPT ); Fri, 1 Oct 2010 07:07:12 -0400 Date: Fri, 1 Oct 2010 13:57:11 +0300 From: David Cohen To: ext Fernando Guzman Lugo Cc: "Doyu Hiroshi (Nokia-MS/Espoo)" , "Contreras Felipe (Nokia-MS/Helsinki)" , "Palande Ameya (Nokia-MS/Helsinki)" , "linux-kernel@vger.kernel.org" , "andy.shevchenko@gmail.com" , "linux-omap@vger.kernel.org" Subject: Re: [PATCH 2/4] iovmm: fix roundup for next area and end check for the last area Message-ID: <20101001105711.GA11617@esdhcp036161.research.nokia.com> References: <1285902536-7043-1-git-send-email-x0095840@ti.com> <1285902536-7043-2-git-send-email-x0095840@ti.com> <1285902536-7043-3-git-send-email-x0095840@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1285902536-7043-3-git-send-email-x0095840@ti.com> User-Agent: Mutt/1.5.20 (2009-06-14) X-OriginalArrivalTime: 01 Oct 2010 11:06:59.0161 (UTC) FILETIME=[C47B1C90:01CB6158] X-Nokia-AV: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Fri, Oct 01, 2010 at 05:08:53AM +0200, ext Fernando Guzman Lugo wrote: > As da_end does not belongs to the area the roundup should > be done to da_end and not to da_end + 1. > Also the end check for the last area should be > ULONG_MAX - start + 1 >= bytes. > > Signed-off-by: Fernando Guzman Lugo > --- > arch/arm/plat-omap/iovmm.c | 6 +++--- > 1 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/arm/plat-omap/iovmm.c b/arch/arm/plat-omap/iovmm.c > index 24ca9c4..fc6b109 100644 > --- a/arch/arm/plat-omap/iovmm.c > +++ b/arch/arm/plat-omap/iovmm.c > @@ -289,19 +289,19 @@ static struct iovm_struct *alloc_iovm_area(struct iommu *obj, u32 da, > prev_end = 0; > list_for_each_entry(tmp, &obj->mmap, list) { > > - if (prev_end >= start) > + if (prev_end > start) > break; > > if (start + bytes <= tmp->da_start) > goto found; > > if (flags & IOVMF_DA_ANON) > - start = roundup(tmp->da_end + 1, alignement); > + start = roundup(tmp->da_end, alignement); There's a lack of comment here, but the purpose of tmp->da_end + 1 is to create a gap between iovm areas to force to trigger iommu faults when some access exceeds a valid area. Without this gap, such situation may produce data corruption which is much more difficult to track. Br, David > > prev_end = tmp->da_end; > } > > - if ((start > prev_end) && (ULONG_MAX - start >= bytes)) > + if ((start >= prev_end) && (ULONG_MAX - start + 1 >= bytes)) > goto found; > > dev_dbg(obj->dev, "%s: no space to fit %08x(%x) flags: %08x\n", > -- > 1.6.3.3 > > -- > 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/