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Subject: Re: [PATCH resend v2] lib: scatterlist: Fix to support no mapped sg
To:     Jens Axboe <axboe@fb.com>,
        "robert.jarzmik@free.fr" <robert.jarzmik@free.fr>,
        "axboe@kernel.dk" <axboe@kernel.dk>
References: <1563940463-95597-1-git-send-email-wangzhou1@hisilicon.com>
 <5D3E4F91.4020605@hisilicon.com>
 <ba094177-6dc5-e1f6-d256-8e21d119729e@fb.com>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linuxarm@huawei.com" <linuxarm@huawei.com>
From:   Zhou Wang <wangzhou1@hisilicon.com>
Message-ID: <5D4C2B4F.2040401@hisilicon.com>
Date:   Thu, 8 Aug 2019 22:01:51 +0800
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On 2019/8/8 21:40, Jens Axboe wrote:
> On 7/28/19 6:44 PM, Zhou Wang wrote:
>> On 2019/7/24 11:54, Zhou Wang wrote:
>>> In function sg_split, the second sg_calculate_split will return -EINVAL
>>> when in_mapped_nents is 0.
>>>
>>> Indeed there is no need to do second sg_calculate_split and sg_split_mapped
>>> when in_mapped_nents is 0, as in_mapped_nents indicates no mapped entry in
>>> original sgl.
>>>
>>> Signed-off-by: Zhou Wang <wangzhou1@hisilicon.com>
>>> Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
>>> ---
>>> v2: Just add Acked-by from Robert.
>>>
>>>   lib/sg_split.c | 12 +++++++-----
>>>   1 file changed, 7 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/lib/sg_split.c b/lib/sg_split.c
>>> index 9982c63..60a0bab 100644
>>> --- a/lib/sg_split.c
>>> +++ b/lib/sg_split.c
>>> @@ -176,11 +176,13 @@ int sg_split(struct scatterlist *in, const int in_mapped_nents,
>>>   	 * The order of these 3 calls is important and should be kept.
>>>   	 */
>>>   	sg_split_phys(splitters, nb_splits);
>>> -	ret = sg_calculate_split(in, in_mapped_nents, nb_splits, skip,
>>> -				 split_sizes, splitters, true);
>>> -	if (ret < 0)
>>> -		goto err;
>>> -	sg_split_mapped(splitters, nb_splits);
>>> +	if (in_mapped_nents) {
>>> +		ret = sg_calculate_split(in, in_mapped_nents, nb_splits, skip,
>>> +					 split_sizes, splitters, true);
>>> +		if (ret < 0)
>>> +			goto err;
>>> +		sg_split_mapped(splitters, nb_splits);
>>> +	}
>>>   
>>>   	for (i = 0; i < nb_splits; i++) {
>>>   		out[i] = splitters[i].out_sg;
>>>
>>
>> Hi Jens,
>>
>> I saw you are the committer of sg_splite.c, could you help to take this patch?
> 
> Yes, I can take it for 5.4, it looks fine to me. 

Thanks a lot for taking this patch :)

>