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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Joerg Roedel <joro@8bytes.org>,
        Jerry Snitselaar <jsnitsel@redhat.com>,
        Joerg Roedel <jroedel@suse.de>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.20 014/171] iommu/amd: Unmap all mapped pages in error path of map_sg
Date:   Tue, 12 Mar 2019 10:06:34 -0700
Message-Id: <20190312170349.125089328@linuxfoundation.org>
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4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit f1724c0883bb0ce93b8dcb94b53dcca3b75ac9a7 ]

In the error path of map_sg there is an incorrect if condition
for breaking out of the loop that searches the scatterlist
for mapped pages to unmap. Instead of breaking out of the
loop once all the pages that were mapped have been unmapped,
it will break out of the loop after it has unmapped 1 page.
Fix the condition, so it breaks out of the loop only after
all the mapped pages have been unmapped.

Fixes: 80187fd39dcb ("iommu/amd: Optimize map_sg and unmap_sg")
Cc: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/iommu/amd_iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 5f33f843d30a..ca3a250d8fa7 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -2555,7 +2555,7 @@ static int map_sg(struct device *dev, struct scatterlist *sglist,
 			bus_addr  = address + s->dma_address + (j << PAGE_SHIFT);
 			iommu_unmap_page(domain, bus_addr, PAGE_SIZE);
 
-			if (--mapped_pages)
+			if (--mapped_pages == 0)
 				goto out_free_iova;
 		}
 	}
-- 
2.19.1