From: John Garry <john.garry@huawei.com>
To: <joro@8bytes.org>
Cc: Cong Wang <xiyou.wangcong@gmail.com>,
iommu@lists.linux-foundation.org,
Robin Murphy <robin.murphy@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [Patch v3 3/3] iommu: avoid taking iova_rbtree_lock twice
Date: Tue, 3 Mar 2020 11:33:10 +0000 [thread overview]
Message-ID: <4b74d40a-22d1-af53-fcb6-5d70183705a8@huawei.com> (raw)
In-Reply-To: <2ff1002c-28b3-a863-49d2-3eab5b5ea778@arm.com>
On 21/01/2020 09:56, Robin Murphy wrote:
> On 18/12/2019 4:39 am, 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.
>
> Makes sense to me.
>
> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: John Garry <john.garry@huawei.com>
Could we at least get this patch picked up? It should be ok to take in
isolation, since there is some debate on the other 2 patches in this
series. Thanks
>
>> Cc: Joerg Roedel <joro@8bytes.org>
>> Cc: John Garry <john.garry@huawei.com>
>> 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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next prev parent reply other threads:[~2020-03-03 11:33 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
2020-01-21 9:56 ` Robin Murphy
2020-03-03 11:33 ` John Garry [this message]
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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