linux-kernel - Re: [PATCH 2/4] Bug Fix drivers/pci/intel-iommu.c: secure sg

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Message-Id: <1249459799.9324.348.camel@macbook.infradead.org>
Date:	Wed, 05 Aug 2009 09:09:59 +0100
From:	David Woodhouse <dwmw2@...radead.org>
To:	Fenghua Yu <fenghua.yu@...el.com>
Cc:	Tony Luck <tony.luck@...el.com>, iommu@...ts.linux-foundation.org,
	linux-ia64@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] Bug Fix drivers/pci/intel-iommu.c: secure
 sg_next() calling

On Tue, 2009-08-04 at 15:10 -0700, Fenghua Yu wrote:
> sg_next() is called only when sg is not NULL. This solves a kernel panic on
> some platforms (e.g. ia64).

Is this still necessary after we fix the other bugs? When does it
happen? And is this fix sufficient (ignore the first hunk; it's just a
cleanup that the fix allows me to make, which is why I'd prefer to do it
this way):

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 11b317a..c9bdb0b 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -1675,7 +1675,7 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
 	if (sg)
 		sg_res = 0;
 	else {
-		sg_res = nr_pages + 1;
+		sg_res = nr_pages;
 		pteval = ((phys_addr_t)phys_pfn << VTD_PAGE_SHIFT) | prot;
 	}
 
@@ -1716,7 +1716,7 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
 		iov_pfn++;
 		pteval += VTD_PAGE_SIZE;
 		sg_res--;
-		if (!sg_res)
+		if (nr_pages && !sg_res)
 			sg = sg_next(sg);
 	}
 	return 0;


-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@...el.com                              Intel Corporation

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