[PATCH] i386: make pci_map_single/pci_map_sg warn for zero length.

As suggested by Linus.

This catches driver bugs that could cause corruption on IOMMU architectures.

Also I converted the BUGs to out_of_line_bug()s to save a bit
of text space.

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

1 files changed, 9 insertions, 3 deletions

diff --git a/include/asm-i386/dma-mapping.h b/include/asm-i386/dma-mapping.h
index 6c37a9ab8d60..9cf20cacf76e 100644
--- a/include/asm-i386/dma-mapping.h
+++ b/include/asm-i386/dma-mapping.h
@@ -6,6 +6,7 @@
 #include <asm/cache.h>
 #include <asm/io.h>
 #include <asm/scatterlist.h>
+#include <asm/bug.h>
 
 #define dma_alloc_noncoherent(d, s, h, f) dma_alloc_coherent(d, s, h, f)
 #define dma_free_noncoherent(d, s, v, h) dma_free_coherent(d, s, v, h)
@@ -20,7 +21,9 @@ static inline dma_addr_t
 dma_map_single(struct device *dev, void *ptr, size_t size,
                enum dma_data_direction direction)
 {
-        BUG_ON(direction == DMA_NONE);
+        if (direction == DMA_NONE)
+                BUG();
+        WARN_ON(size == 0);
         flush_write_buffers();
         return virt_to_phys(ptr);
 }
@@ -29,7 +32,8 @@ static inline void
 dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
                  enum dma_data_direction direction)
 {
-        BUG_ON(direction == DMA_NONE);
+        if (direction == DMA_NONE)
+                BUG();
 }
 
 static inline int
@@ -38,7 +42,9 @@ dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 {
         int i;
 
-        BUG_ON(direction == DMA_NONE);
+        if (direction == DMA_NONE)
+                BUG();
+        WARN_ON(nents == 0 || sg[0].length == 0);
 
         for (i = 0; i < nents; i++ ) {
                 BUG_ON(!sg[i].page);