On 29/11/2019 00:48, Cong Wang wrote:
Both find_iova() and __free_iova() take iova_rbtree_lock,
there is no reason to take and release it twice inside
free_iova().

Fold them into the critical section by calling the unlock
versions instead.

Since generally the iova would be non-NULL, this seems a reasonable change (which could be mentioned in the commit log)

John


Cc: Joerg Roedel <j...@8bytes.org>
Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
---
  drivers/iommu/iova.c | 8 ++++++--
  1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index 184d4c0e20b5..f46f8f794678 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -390,10 +390,14 @@ EXPORT_SYMBOL_GPL(__free_iova);
  void
  free_iova(struct iova_domain *iovad, unsigned long pfn)
  {
-       struct iova *iova = find_iova(iovad, pfn);
+       unsigned long flags;
+       struct iova *iova;
+ spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
+       iova = private_find_iova(iovad, pfn);
        if (iova)
-               __free_iova(iovad, iova);
+               private_free_iova(iovad, iova);
+       spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
}
  EXPORT_SYMBOL_GPL(free_iova);


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