linux-kernel - Re: [PATCH 1/1] swiotlb: save io_tlb_used to local variable before leaving critical section

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Date:   Fri, 12 Apr 2019 07:13:59 -0700
From:   Joe Jin <joe.jin@...cle.com>
To:     Dongli Zhang <dongli.zhang@...cle.com>,
        iommu@...ts.linux-foundation.org, konrad.wilk@...cle.com
Cc:     linux-kernel@...r.kernel.org, hch@....de, m.szyprowski@...sung.com,
        robin.murphy@....com, haakon.bugge@...cle.com
Subject: Re: [PATCH 1/1] swiotlb: save io_tlb_used to local variable before
 leaving critical section

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@...cle.com>
> Signed-off-by: Dongli Zhang <dongli.zhang@...cle.com>

Reviewed-by: Joe Jin <joe.jin@...cle.com> 

Thanks,
Joe