From: Jens Axboe <axboe@kernel.dk>
Subject: Re: [RFC v2 1/3] block: Introduce blk_bio_map_sg() to map one bio
Date: Fri, 3 Jun 2016 08:38:40 -0600
Message-ID: <57519670.6050306@kernel.dk>
References: <cover.1464346333.git.baolin.wang@linaro.org>
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To: Baolin Wang <baolin.wang@linaro.org>, agk@redhat.com,
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On 05/27/2016 05:11 AM, Baolin Wang wrote:
> +/*
> + * Map a bio to scatterlist, return number of sg entries setup. Caller must
> + * make sure sg can hold bio segments entries.
> + */
> +int blk_bio_map_sg(struct request_queue *q, struct bio *bio,
> +		   struct scatterlist *sglist)
> +{
> +	struct scatterlist *sg = NULL;
> +	int nsegs = 0;
> +
> +	if (bio)
> +		nsegs = __blk_bios_map_sg(q, bio, sglist, &sg, true);
> +
> +	if (sg)
> +		sg_mark_end(sg);

Put that if (sg) inside the if (bio) section, 'sg' isn't going to be
non-NULL outside of that.

Additionally, who would call this with a NULL bio? That seems odd, I'd
get rid of that check completely.

-- 
Jens Axboe