linux-kernel - [PATCH 1/4] iommu/amd: clean up the cmpxchg64 invocation

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Message-Id: <1473929453-3533-2-git-send-email-bhe@redhat.com>
Date:   Thu, 15 Sep 2016 16:50:50 +0800
From:   Baoquan He <bhe@...hat.com>
To:     joro@...tes.org
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        dyoung@...hat.com, xlpang@...hat.com, Vincent.Wan@....com,
        Baoquan He <bhe@...hat.com>
Subject: [PATCH 1/4] 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@...hat.com>
---
 drivers/iommu/amd_iommu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 96de97a..160fc6a 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1274,7 +1274,8 @@ 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;
 			}
-- 
2.5.5