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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: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2013-03-20 15:44:26 +10:30
parent 13816c768d
commit 282edb3649
2 changed files with 54 additions and 0 deletions
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44
drivers/virtio/virtio_ring.c
View File

@ -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

10
include/linux/virtio.h
View File

@ -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,