linux-kernel - Re: [PATCH 2/2] swiotlb: Skip cache maintenance on map error

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Message-ID: <20181120160753.GB2492@lst.de>
Date:   Tue, 20 Nov 2018 17:07:53 +0100
From:   Christoph Hellwig <hch@....de>
To:     Robin Murphy <robin.murphy@....com>
Cc:     hch@....de, konrad.wilk@...cle.com, m.szyprowski@...sung.com,
        john.stultz@...aro.org, iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] swiotlb: Skip cache maintenance on map error

On Tue, Nov 20, 2018 at 02:09:53PM +0000, Robin Murphy wrote:
> If swiotlb_bounce_page() failed, calling arch_sync_dma_for_device() may
> lead to such delights as performing cache maintenance on whatever
> address phys_to_virt(SWIOTLB_MAP_ERROR) looks like, which is typically
> outside the kernel memory map and goes about as well as expected.
> 
> Don't do that.
> 
> Fixes: a4a4330db46a ("swiotlb: add support for non-coherent DMA")
> Signed-off-by: Robin Murphy <robin.murphy@....com>

Looks good,

Reviewed-by: Christoph Hellwig <hch@....de>