On 2018/5/31 21:03, Robin Murphy wrote:

On 31/05/18 08:42, Zhen Lei wrote:

quoted

The static function iova_reserve_iommu_regions is only called by function
iommu_dma_init_domain, and the 'if (!dev)' check in iommu_dma_init_domain
affect it only, so we can safely move the check into it. I think it looks
more natural.

As before, I disagree - the logic of iommu_dma_init_domain() is "we expect to have a valid device, but stop here if we don't", and moving the check just needlessly obfuscates that. It is not a coincidence that the arguments of both functions are in effective order of importance.

OK

quoted

In addition, the local variable 'ret' is only assigned in the branch of
'if (region->type == IOMMU_RESV_MSI)', so the 'if (ret)' should also only
take effect in the branch, add a brace to enclose it.

'ret' is clearly also assigned at its declaration, to cover the (very likely) case where we don't enter the loop at all. Thus testing it in the loop is harmless, and cluttering that up with extra tabs and braces is just noise.

OK, I will drop this patch in v2

Robin.

quoted

No functional changes.

Signed-off-by: Zhen Lei <redacted>
---
  drivers/iommu/dma-iommu.c | 12 +++++++-----
  1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index ddcbbdb..4e885f7 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c

@@ -231,6 +231,9 @@ static int iova_reserve_iommu_regions(struct device *dev,
      LIST_HEAD(resv_regions);
      int ret = 0;
  +    if (!dev)
+        return 0;
+
      if (dev_is_pci(dev))
          iova_reserve_pci_windows(to_pci_dev(dev), iovad);
  @@ -246,11 +249,12 @@ static int iova_reserve_iommu_regions(struct device *dev,
          hi = iova_pfn(iovad, region->start + region->length - 1);
          reserve_iova(iovad, lo, hi);
  -        if (region->type == IOMMU_RESV_MSI)
+        if (region->type == IOMMU_RESV_MSI) {
              ret = cookie_init_hw_msi_region(cookie, region->start,
                      region->start + region->length);
-        if (ret)
-            break;
+            if (ret)
+                break;
+        }
      }
      iommu_put_resv_regions(dev, &resv_regions);
  @@ -308,8 +312,6 @@ int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
      }
        init_iova_domain(iovad, 1UL << order, base_pfn);
-    if (!dev)
-        return 0;
        return iova_reserve_iommu_regions(dev, domain);
  }

.

-- 
Thanks!
BestRegards