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

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Date:   Mon, 15 Apr 2019 14:50:49 +0800
From:   Dongli Zhang <dongli.zhang@...cle.com>
To:     Joe Jin <joe.jin@...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

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@...cle.com>
>> Signed-off-by: Dongli Zhang <dongli.zhang@...cle.com>
> 
> Reviewed-by: Joe Jin <joe.jin@...cle.com> 
> 
> Thanks,
> Joe
>