[PATCH] Fix swiotlb pci_map_sg error handling

The overflow checking condition in lib/swiotlb.c was wrong.
It would first run a NULL pointer through virt_to_phys before
testing it. Since pci_map_sg overflow is not that uncommon
and causes data corruption (including broken file systems) when not
properly detected I think it's better to fix it in 2.6.15.

This affects x86-64 and IA64.

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

1 files changed, 3 insertions, 2 deletions

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 57216f3544ca..1ff8dcebf7c6 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -704,8 +704,9 @@ swiotlb_map_sg(struct device *hwdev, struct scatterlist *sg, int nelems,
                 addr = SG_ENT_VIRT_ADDRESS(sg);
                 dev_addr = virt_to_phys(addr);
                 if (swiotlb_force || address_needs_mapping(hwdev, dev_addr)) {
-                        sg->dma_address = (dma_addr_t) virt_to_phys(map_single(hwdev, addr, sg->length, dir));
-                        if (!sg->dma_address) {
+                        void *map = map_single(hwdev, addr, sg->length, dir);
+                        sg->dma_address = virt_to_bus(map);
+                        if (!map) {
                                 /* Don't panic here, we expect map_sg users
                                    to do proper error handling. */
                                 swiotlb_full(hwdev, sg->length, dir, 0);