iommu/amd: Clean up the cmpxchg64 invocation

Change it as it's designed for and keep it consistent with other
places.

Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index bebe728019af..897940c79a54 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1342,7 +1342,8 @@ static u64 *alloc_pte(struct protection_domain *domain,
 
                         __npte = PM_LEVEL_PDE(level, virt_to_phys(page));
 
-                        if (cmpxchg64(pte, __pte, __npte)) {
+                        /* pte could have been changed somewhere. */
+                        if (cmpxchg64(pte, __pte, __npte) != __pte) {
                                 free_page((unsigned long)page);
                                 continue;
                         }