Re: [RESEND PATCH v3] iommu/iova: put free_iova_mem() outside of spinlock iova_rbtree_lock

[Robin Murphy]

On 2021-05-10 12:53, chenxiang wrote:

From: Xiang Chen <chenxian...@hisilicon.com>

It is not necessary to put free_iova_mem() inside of spinlock/unlock
iova_rbtree_lock which only leads to more completion for the spinlock.
It has a small promote on the performance after the change. And also
rename private_free_iova() as remove_iova() because the function will not
free iova after that change.

Acked-by: Robin Murphy <robin.mur...@arm.com>

Signed-off-by: Xiang Chen <chenxian...@hisilicon.com>
Reviewed-by: John Garry <john.ga...@huawei.com>
---
  drivers/iommu/iova.c | 18 +++++++++++-------
  1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index b7ecd5b..b6cf5f1 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -412,12 +412,11 @@ private_find_iova(struct iova_domain *iovad, unsigned 
long pfn)
        return NULL;
  }

-static void private_free_iova(struct iova_domain *iovad, struct iova *iova)

+static void remove_iova(struct iova_domain *iovad, struct iova *iova)
  {
        assert_spin_locked(&iovad->iova_rbtree_lock);
        __cached_rbnode_delete_update(iovad, iova);
        rb_erase(&iova->node, &iovad->rbroot);
-       free_iova_mem(iova);
  }

/**

@@ -452,8 +451,9 @@ __free_iova(struct iova_domain *iovad, struct iova *iova)
        unsigned long flags;

spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);

-       private_free_iova(iovad, iova);
+       remove_iova(iovad, iova);
        spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
+       free_iova_mem(iova);
  }
  EXPORT_SYMBOL_GPL(__free_iova);

@@ -472,10 +472,13 @@ free_iova(struct iova_domain *iovad, unsigned long pfn) spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);

        iova = private_find_iova(iovad, pfn);
-       if (iova)
-               private_free_iova(iovad, iova);
+       if (!iova) {
+               spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
+               return;
+       }
+       remove_iova(iovad, iova);
        spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
-
+       free_iova_mem(iova);
  }
  EXPORT_SYMBOL_GPL(free_iova);

@@ -825,7 +828,8 @@ iova_magazine_free_pfns(struct iova_magazine *mag, struct iova_domain *iovad)

                if (WARN_ON(!iova))
                        continue;

- private_free_iova(iovad, iova);

+               remove_iova(iovad, iova);
+               free_iova_mem(iova);
        }

spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);

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