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Subject: Re: [PATCH] swiotlb: Fix type of max_slot
To:     Kunihiko Hayashi <hayashi.kunihiko@socionext.com>,
        Christoph Hellwig <hch@lst.de>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Jianxiong Gao <jxgao@google.com>
Cc:     iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
References: <1614705688-10567-1-git-send-email-hayashi.kunihiko@socionext.com>
From:   Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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On 3/2/21 12:21 PM, Kunihiko Hayashi wrote:
> After the refactoring phase, the type of max_slot has changed from unsigned
> long to unsigned int. The return type of the function get_max_slots() and
> the 4th argument type of iommu_is_span_boundary() are different from the
> type of max_slot. Finally, asserts BUG_ON in iommu_is_span_boundary().
> 
> Cc: Christoph Hellwig <hch@lst.de>
> Fixes: 567d877f9a7d ("swiotlb: refactor swiotlb_tbl_map_single")
> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>

I think this is all good. Looking at Linus's master I see:


537         unsigned long max_slots = get_max_slots(boundary_mask);

?

> ---
>   kernel/dma/swiotlb.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 369e4c3..c10e855 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -534,7 +534,7 @@ static int find_slots(struct device *dev, phys_addr_t orig_addr,
>   	unsigned long boundary_mask = dma_get_seg_boundary(dev);
>   	dma_addr_t tbl_dma_addr =
>   		phys_to_dma_unencrypted(dev, io_tlb_start) & boundary_mask;
> -	unsigned int max_slots = get_max_slots(boundary_mask);
> +	unsigned long max_slots = get_max_slots(boundary_mask);
>   	unsigned int iotlb_align_mask =
>   		dma_get_min_align_mask(dev) & ~(IO_TLB_SIZE - 1);
>   	unsigned int nslots = nr_slots(alloc_size), stride;
>