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Re: [PATCH v1 4/7] iommu/vt-d: Remove unnecessary local variable initializations




Hi,

On 2/9/19 6:06 AM, Bjorn Helgaas wrote:
From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

A local variable initialization is a hint that the variable will be used in
an unusual way.  If the initialization is unnecessary, that hint becomes a
distraction.

Remove unnecessary initializations.  No functional change intended.

Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
---
  drivers/iommu/intel-iommu.c |   27 +++++++++++++--------------
  1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 81077803880f..2acd08c82cdc 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -865,7 +865,7 @@ static void free_context_table(struct intel_iommu *iommu)
  static struct dma_pte *pfn_to_dma_pte(struct dmar_domain *domain,
  				      unsigned long pfn, int *target_level)
  {
-	struct dma_pte *parent, *pte = NULL;
+	struct dma_pte *parent, *pte;
  	int level = agaw_to_level(domain->agaw);
  	int offset;
@@ -922,7 +922,7 @@ static struct dma_pte *dma_pfn_level_pte(struct dmar_domain *domain,
  					 unsigned long pfn,
  					 int level, int *large_page)
  {
-	struct dma_pte *parent, *pte = NULL;
+	struct dma_pte *parent, *pte;
  	int total = agaw_to_level(domain->agaw);
  	int offset;
@@ -954,7 +954,7 @@ static void dma_pte_clear_range(struct dmar_domain *domain,
  				unsigned long start_pfn,
  				unsigned long last_pfn)
  {
-	unsigned int large_page = 1;
+	unsigned int large_page;
  	struct dma_pte *first_pte, *pte;
BUG_ON(!domain_pfn_supported(domain, start_pfn));
@@ -1132,7 +1132,7 @@ static struct page *domain_unmap(struct dmar_domain *domain,
  				 unsigned long start_pfn,
  				 unsigned long last_pfn)
  {
-	struct page *freelist = NULL;
+	struct page *freelist;

I am afraid this change might cause problem. "freelist" might go through
dma_pte_clear_level() without any touches.

Best regards,
Lu Baolu