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Date:   Wed, 13 Jan 2021 13:44:16 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Claire Chang <tientzu@chromium.org>
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Subject: Re: [RFC PATCH v3 3/6] swiotlb: Use restricted DMA pool if
 available
Message-ID: <20210113124416.GB1383@lst.de>
References: <20210106034124.30560-1-tientzu@chromium.org> <20210106034124.30560-4-tientzu@chromium.org>
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> +#ifdef CONFIG_SWIOTLB
> +	if (unlikely(swiotlb_force == SWIOTLB_FORCE) || dev->dma_io_tlb_mem)
>  		return swiotlb_map(dev, phys, size, dir, attrs);
> +#endif

Please provide a wrapper for the dev->dma_io_tlb_mem check that
always returns false if the per-device swiotlb support is not enabled.

> index 7fb2ac087d23..1f05af09e61a 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -222,7 +222,6 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
>  		mem->orig_addr[i] = INVALID_PHYS_ADDR;
>  	}
>  	mem->index = 0;
> -	no_iotlb_memory = false;

How does this fit in here?