[PATCH] x86_64: GART DMA merging fix

Don't touch the non DMA members in the sg list in dma_map_sg in the IOMMU

Some drivers (in particular ST) ran into problems because they reused the sg
lists after passing them to pci_map_sg().  The merging procedure in the K8
GART IOMMU corrupted the state.  This patch changes it to only touch the dma*
entries during merging, but not the other fields.  Approach suggested by Dave
Miller.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 4 deletions

diff --git a/arch/x86_64/kernel/pci-gart.c b/arch/x86_64/kernel/pci-gart.c
index 2fe23a6c361b..dd0718dc178b 100644
--- a/arch/x86_64/kernel/pci-gart.c
+++ b/arch/x86_64/kernel/pci-gart.c
@@ -310,7 +310,7 @@ void gart_unmap_sg(struct device *dev, struct scatterlist *sg, int nents, int di
 
         for (i = 0; i < nents; i++) {
                 struct scatterlist *s = &sg[i];
-                if (!s->dma_length || !s->length)
+                if (!s->dma_length)
                         break;
                 dma_unmap_single(dev, s->dma_address, s->dma_length, dir);
         }
@@ -364,7 +364,6 @@ static int __dma_map_cont(struct scatterlist *sg, int start, int stopat,
                 
                 BUG_ON(i > start && s->offset);
                 if (i == start) {
-                        *sout = *s; 
                         sout->dma_address = iommu_bus_base;
                         sout->dma_address += iommu_page*PAGE_SIZE + s->offset;
                         sout->dma_length = s->length;
@@ -379,7 +378,7 @@ static int __dma_map_cont(struct scatterlist *sg, int start, int stopat,
                         SET_LEAK(iommu_page);
                         addr += PAGE_SIZE;
                         iommu_page++;
-        } 
+                }
         } 
         BUG_ON(iommu_page - iommu_start != pages);      
         return 0;
@@ -391,7 +390,6 @@ static inline int dma_map_cont(struct scatterlist *sg, int start, int stopat,
 {
         if (!need) { 
                 BUG_ON(stopat - start != 1);
-                *sout = sg[start]; 
                 sout->dma_length = sg[start].length; 
                 return 0;
         }