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Subject: Re: [PATCH 1/1] swiotlb: save io_tlb_used to local variable before
 leaving critical section
To:     Dongli Zhang <dongli.zhang@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>
From:   Joe Jin <joe.jin@oracle.com>
Message-ID: <5bdc3265-e5a4-e8c8-9098-0bba18a66f19@oracle.com>
Date:   Fri, 12 Apr 2019 07:13:59 -0700
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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