[PATCH 3.2 036/101] x86/pci-calgary: Fix iommu_free() comparison of unsigned expression >= 0

[PATCH 3.2 036/101] x86/pci-calgary: Fix iommu_free() comparison of unsigned expression >= 0

[Ben Hutchings]

3.2.89-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Nikola Pajkovsky <npajkovsky@suse.cz>

commit 68dee8e2f2cacc54d038394e70d22411dee89da2 upstream.

commit 8fd524b355da ("x86: Kill bad_dma_address variable") has killed
bad_dma_address variable and used instead of macro DMA_ERROR_CODE
which is always zero. Since dma_addr is unsigned, the statement

   dma_addr >= DMA_ERROR_CODE

is always true, and not needed.

arch/x86/kernel/pci-calgary_64.c: In function ‘iommu_free’:
arch/x86/kernel/pci-calgary_64.c:299:2: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
  if (unlikely((dma_addr >= DMA_ERROR_CODE) && (dma_addr < badend))) {

Fixes: 8fd524b355da ("x86: Kill bad_dma_address variable")
Signed-off-by: Nikola Pajkovsky <npajkovsky@suse.cz>
Cc: iommu@lists.linux-foundation.org
Cc: Jon Mason <jdmason@kudzu.us>
Cc: Muli Ben-Yehuda <mulix@mulix.org>
Link: http://lkml.kernel.org/r/7612c0f9dd7c1290407dbf8e809def922006920b.1479161177.git.npajkovsky@suse.cz
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 arch/x86/kernel/pci-calgary_64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kernel/pci-calgary_64.c
+++ b/arch/x86/kernel/pci-calgary_64.c
@@ -295,7 +295,7 @@ static void iommu_free(struct iommu_tabl
 
 	/* were we called with bad_dma_address? */
 	badend = DMA_ERROR_CODE + (EMERGENCY_PAGES * PAGE_SIZE);
-	if (unlikely((dma_addr >= DMA_ERROR_CODE) && (dma_addr < badend))) {
+	if (unlikely(dma_addr < badend)) {
 		WARN(1, KERN_ERR "Calgary: driver tried unmapping bad DMA "
 		       "address 0x%Lx\n", dma_addr);
 		return;

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