Re: [PATCH] swiotlb: clear io_tlb_start and io_tlb_end in swiotlb_exit

[Konrad Rzeszutek Wilk <konrad.wilk-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

On Mon, Jan 14, 2019 at 09:14:08PM +0100, Christoph Hellwig wrote:
> Otherwise is_swiotlb_buffer will return false positives when
> we first initialize a swiotlb buffer, but then free it because
> we have an IOMMU available.
> 
> Fixes: 55897af63091 ("dma-direct: merge swiotlb_dma_ops into the dma_direct code")
> Reported-by: Sibren Vasse <sibren-DLwv2wemLo05ZU0pBKPMFg@public.gmane.org>
> Signed-off-by: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
> Tested-by: Sibren Vasse <sibren-DLwv2wemLo05ZU0pBKPMFg@public.gmane.org>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>

Thank you!
> ---
>  kernel/dma/swiotlb.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index d6361776dc5c..1fb6fd68b9c7 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -378,6 +378,8 @@ void __init swiotlb_exit(void)
>  		memblock_free_late(io_tlb_start,
>  				   PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
>  	}
> +	io_tlb_start = 0;
> +	io_tlb_end = 0;
>  	io_tlb_nslabs = 0;
>  	max_segment = 0;
>  }
> -- 
> 2.20.1
>