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Date: Thu, 28 Mar 2024 16:36:12 +0900
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Subject: Re: [PATCH v2] scsi: libsas: Allocation SMP request is aligned to
 ARCH_DMA_MINALIGN
To: Christoph Hellwig <hch@infradead.org>
Cc: Yihang Li <liyihang9@huawei.com>, John Garry <john.g.garry@oracle.com>,
 yanaijie@huawei.com, jejb@linux.ibm.com, martin.petersen@oracle.com,
 chenxiang66@hisilicon.com, linux-scsi@vger.kernel.org,
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 yangxingui@huawei.com
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From: Damien Le Moal <dlemoal@kernel.org>
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Organization: Western Digital Research
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On 3/28/24 16:29, Christoph Hellwig wrote:
> On Thu, Mar 28, 2024 at 04:23:22PM +0900, Damien Le Moal wrote:
>> But I thought that the original issue was that some arch have ARCH_DMA_MINALIGN
>> down to 8B but hisi driver needs at least 16 ?
>>
>> So in the end, you need something like:
>>
>> 	size = ALIGN(size, max(16, ARCH_DMA_MINALIGN));
>>
>> no ?
> 
> I don't think we ever have an 8 byte dma minalign.  With 8-byte
> aligned addresses dma_mapping_error could run into problems.

My bad: it is kmalloc() that can return something aligned to 8B...
So "size = ALIGN(size, ARCH_DMA_MINALIGN);" is the right thing to do.

-- 
Damien Le Moal
Western Digital Research