[Patch v2 3/3] iommu: avoid taking iova_rbtree_lock twice

Cong Wang
2019-11-29T00:49:27Z

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.

Cc: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Cong Wang <xiyou.wangcong@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);
--
2.21.0