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Commit 282edb36 authored by Rusty Russell's avatar Rusty Russell
Browse files

virtio_ring: virtqueue_add_outbuf / virtqueue_add_inbuf. 



These are specialized versions of virtqueue_add_buf(), which cover
over 80% of cases and are far clearer.

In particular, the scatterlists passed to these functions don't have
to be clean (ie. we ignore end markers).

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 13816c76

drivers/virtio/virtio_ring.c

+44 −0
Original line number Diff line number Diff line
@@ -365,6 +365,50 @@ int virtqueue_add_sgs(struct virtqueue *_vq, 
}

EXPORT_SYMBOL_GPL(virtqueue_add_sgs);



/**

 * virtqueue_add_outbuf - expose output buffers to other end

 * @vq: the struct virtqueue we're talking about.

 * @sgs: array of scatterlists (need not be terminated!)

 * @num: the number of scatterlists readable by other side

 * @data: the token identifying the buffer.

 * @gfp: how to do memory allocations (if necessary).

 *

 * Caller must ensure we don't call this with other virtqueue operations

 * at the same time (except where noted).

 *

 * Returns zero or a negative error (ie. ENOSPC, ENOMEM).

 */

int virtqueue_add_outbuf(struct virtqueue *vq,

			 struct scatterlist sg[], unsigned int num,

			 void *data,

			 gfp_t gfp)

{

	return virtqueue_add(vq, &sg, sg_next_arr, num, 0, 1, 0, data, gfp);

}

EXPORT_SYMBOL_GPL(virtqueue_add_outbuf);



/**

 * virtqueue_add_inbuf - expose input buffers to other end

 * @vq: the struct virtqueue we're talking about.

 * @sgs: array of scatterlists (need not be terminated!)

 * @num: the number of scatterlists writable by other side

 * @data: the token identifying the buffer.

 * @gfp: how to do memory allocations (if necessary).

 *

 * Caller must ensure we don't call this with other virtqueue operations

 * at the same time (except where noted).

 *

 * Returns zero or a negative error (ie. ENOSPC, ENOMEM).

 */

int virtqueue_add_inbuf(struct virtqueue *vq,

			struct scatterlist sg[], unsigned int num,

			void *data,

			gfp_t gfp)

{

	return virtqueue_add(vq, &sg, sg_next_arr, 0, num, 0, 1, data, gfp);

}

EXPORT_SYMBOL_GPL(virtqueue_add_inbuf);



/**

 * virtqueue_kick_prepare - first half of split virtqueue_kick call.

 * @vq: the struct virtqueue

include/linux/virtio.h

+10 −0
Original line number Diff line number Diff line
@@ -41,6 +41,16 @@ int virtqueue_add_buf(struct virtqueue *vq, 
		      void *data,

		      gfp_t gfp);



int virtqueue_add_outbuf(struct virtqueue *vq,

			 struct scatterlist sg[], unsigned int num,

			 void *data,

			 gfp_t gfp);



int virtqueue_add_inbuf(struct virtqueue *vq,

			struct scatterlist sg[], unsigned int num,

			void *data,

			gfp_t gfp);



int virtqueue_add_sgs(struct virtqueue *vq,

		      struct scatterlist *sgs[],

		      unsigned int out_sgs,