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Subject: Re: [PATCH 1/1] swiotlb: save io_tlb_used to local variable before
 leaving critical section
To:     Joe Jin <joe.jin@oracle.com>, iommu@lists.linux-foundation.org,
        konrad.wilk@oracle.com
Cc:     linux-kernel@vger.kernel.org, hch@lst.de, m.szyprowski@samsung.com,
        robin.murphy@arm.com, haakon.bugge@oracle.com
References: <1555069106-2964-1-git-send-email-dongli.zhang@oracle.com>
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From:   Dongli Zhang <dongli.zhang@oracle.com>
Message-ID: <38f6f868-013e-5619-b939-a8273fc64ee4@oracle.com>
Date:   Mon, 15 Apr 2019 14:50:49 +0800
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As the patch to be fixed is still in Konrad's own tree, I will send the v2 for
the patch to be fixed, instead of an incremental fix.

Dongli Zhang

On 4/12/19 10:13 PM, Joe Jin wrote:
> I'm good to have this patch, which helps identify the cause of failure is
> fragmentation or it really been used up.
> 
> On 4/12/19 4:38 AM, Dongli Zhang wrote:
>> When swiotlb is full, the kernel would print io_tlb_used. However, the
>> result might be inaccurate at that time because we have left the critical
>> section protected by spinlock.
>>
>> Therefore, we backup the io_tlb_used into local variable before leaving
>> critical section.
>>
>> Fixes: 83ca25948940 ("swiotlb: dump used and total slots when swiotlb buffer is full")
>> Suggested-by: Håkon Bugge <haakon.bugge@oracle.com>
>> Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
> 
> Reviewed-by: Joe Jin <joe.jin@oracle.com> 
> 
> Thanks,
> Joe
>