On 09/26/2012 06:38 PM, Tejun Heo wrote:
> (cc'ing Jens)
>
> On Wed, Sep 26, 2012 at 11:49:00AM +0200, Maxim Levitsky wrote:
>> Useful helper to know the number of entries in scatterlist.
>>
>> Signed-off-by: Maxim Levitsky <maximlevit...@gmail.com>
>> ---
>> include/linux/scatterlist.h | 1 +
>> lib/scatterlist.c | 22 ++++++++++++++++++++++
>> 2 files changed, 23 insertions(+)
>>
>> diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
>> index 7b600da..4bd6c06 100644
>> --- a/include/linux/scatterlist.h
>> +++ b/include/linux/scatterlist.h
>> @@ -201,6 +201,7 @@ static inline void *sg_virt(struct scatterlist *sg)
>> return page_address(sg_page(sg)) + sg->offset;
>> }
>>
>> +int sg_nents(struct scatterlist *sg);
>> struct scatterlist *sg_next(struct scatterlist *);
>> struct scatterlist *sg_last(struct scatterlist *s, unsigned int);
>> void sg_init_table(struct scatterlist *, unsigned int);
>> diff --git a/lib/scatterlist.c b/lib/scatterlist.c
>> index e76d85c..5cd9cdc 100644
>> --- a/lib/scatterlist.c
>> +++ b/lib/scatterlist.c
>> @@ -39,6 +39,28 @@ struct scatterlist *sg_next(struct scatterlist *sg)
>> EXPORT_SYMBOL(sg_next);
>>
>> /**
>> + * sg_nents - return total count of entries in scatterlist
>> + * @sg: The scatterlist
>> + *
>> + * Description:
>> + * Allows to know how many entries are in sg, taking into acount
>> + * chaining as well
>> + *
>> + **/
>> +int sg_nents(struct scatterlist *sg)
>> +{
>> + int nents = 0;
>> + while (sg) {
>> + nents++;
>> + sg = sg_next(sg);
>> + }
>> +
>> + return nents;
>> +}
>> +EXPORT_SYMBOL(sg_nents);
>
> How about the following instead?
>
> for (nents = 0; sg; sg = sg_next(sg))
> nents++;
> return nents;
>
> Other than that,
>
> Acked-by: Tejun Heo <t...@kernel.org>
Agree, that'd be cleaner. I've just applied it as-is. Maxim, feel free
to send an update to it. I pulled the driver bit into the
for-3.7/drivers branch as well.
--
Jens Axboe
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