[PATCH] iommu: Up front sanity check in the arm_lpae_map

[Keqian Zhu]

... then we have more chance to detect wrong code logic.

Signed-off-by: Keqian Zhu <zhukeqian1 at huawei.com>
---
 drivers/iommu/io-pgtable-arm.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index a7a9bc08dcd1..8ade72adab31 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -444,10 +444,6 @@ static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova,
 	arm_lpae_iopte prot;
 	long iaext = (s64)iova >> cfg->ias;
 
-	/* If no access, then nothing to do */
-	if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
-		return 0;
-
 	if (WARN_ON(!size || (size & cfg->pgsize_bitmap) != size))
 		return -EINVAL;
 
@@ -456,6 +452,10 @@ static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova,
 	if (WARN_ON(iaext || paddr >> cfg->oas))
 		return -ERANGE;
 
+	/* If no access, then nothing to do */
+	if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
+		return 0;
+
 	prot = arm_lpae_prot_to_pte(data, iommu_prot);
 	ret = __arm_lpae_map(data, iova, paddr, size, prot, lvl, ptep, gfp);
 	/*
-- 
2.23.0