Messages in this thread | | | Subject | Re: [Patch v2 3/3] iommu: avoid taking iova_rbtree_lock twice | From | John Garry <> | Date | Fri, 29 Nov 2019 13:34:03 +0000 |
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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 <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); >
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