From: John Garry <john.garry@huawei.com>
To: Cong Wang <xiyou.wangcong@gmail.com>, <iommu@lists.linux-foundation.org>
Cc: robin.murphy@arm.com, linux-kernel@vger.kernel.org
Subject: Re: [Patch v3 3/3] iommu: avoid taking iova_rbtree_lock twice
Date: Thu, 19 Dec 2019 09:51:15 +0000 [thread overview]
Message-ID: <c0e33d09-8d0e-80b5-1b95-4af82004d9dd@huawei.com> (raw)
In-Reply-To: <20191218043951.10534-4-xiyou.wangcong@gmail.com>
On 18/12/2019 04:39, 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 one critical section by calling the unlock
> versions instead.
>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: John Garry <john.garry@huawei.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
FWIW:
Reviewed-by: John Garry <john.garry@huawei.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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next prev parent reply other threads:[~2019-12-19 9:51 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 4:39 [Patch v3 0/3] iommu: reduce spinlock contention on fast path Cong Wang
2019-12-18 4:39 ` [Patch v3 1/3] iommu: avoid unnecessary magazine allocations Cong Wang
2020-01-21 11:11 ` Robin Murphy
2020-01-21 17:21 ` Cong Wang
2020-01-22 17:07 ` Robin Murphy
2020-01-22 17:54 ` Cong Wang
2019-12-18 4:39 ` [Patch v3 2/3] iommu: optimize iova_magazine_free_pfns() Cong Wang
2020-01-21 9:52 ` Robin Murphy
2020-01-21 17:29 ` Cong Wang
2020-01-22 17:34 ` Robin Murphy
2020-01-22 17:45 ` Cong Wang
2019-12-18 4:39 ` [Patch v3 3/3] iommu: avoid taking iova_rbtree_lock twice Cong Wang
2019-12-19 9:51 ` John Garry [this message]
2020-01-21 9:56 ` Robin Murphy
2020-03-03 11:33 ` John Garry
2020-01-20 23:10 ` [Patch v3 0/3] iommu: reduce spinlock contention on fast path Cong Wang
-- strict thread matches above, loose matches on Subject: below --
2019-12-06 21:38 Cong Wang
2019-12-06 21:38 ` [Patch v3 3/3] iommu: avoid taking iova_rbtree_lock twice Cong Wang
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