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authorRusty Russell <rusty@rustcorp.com.au>2013-03-20 06:14:26 +0100
committerRusty Russell <rusty@rustcorp.com.au>2013-03-20 06:14:52 +0100
commit282edb36499042a92b71f052f51754ae7ed936e4 (patch)
tree5031caab94e52b30e48515e881ea87a32daaeaeb
parentvirtio_ring: virtqueue_add_sgs, to add multiple sgs. (diff)
downloadlinux-282edb36499042a92b71f052f51754ae7ed936e4.tar.xz
linux-282edb36499042a92b71f052f51754ae7ed936e4.zip
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>
-rw-r--r--drivers/virtio/virtio_ring.c44
-rw-r--r--include/linux/virtio.h10
2 files changed, 54 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index a78ad459cc85..5217baf5528c 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -366,6 +366,50 @@ 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
*
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index ac80288b2920..833f17b6a743 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -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,