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>

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>
Rusty Russell
1 parent 13816c768d
Showing 2 changed files with 54 additions and 0 deletions Side-by-side Diff
drivers/virtio/virtio_ring.c
include/linux/virtio.h
@@ -366,6 +366,50 @@
 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
  *
@@ -41,6 +41,16 @@
 		      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,
...	...	@@ -366,6 +366,50 @@
366	366	EXPORT_SYMBOL_GPL(virtqueue_add_sgs);
367	367
368	368	/**
	369	+ * virtqueue_add_outbuf - expose output buffers to other end
	370	+ * @vq: the struct virtqueue we're talking about.
	371	+ * @sgs: array of scatterlists (need not be terminated!)
	372	+ * @num: the number of scatterlists readable by other side
	373	+ * @data: the token identifying the buffer.
	374	+ * @gfp: how to do memory allocations (if necessary).
	375	+ *
	376	+ * Caller must ensure we don't call this with other virtqueue operations
	377	+ * at the same time (except where noted).
	378	+ *
	379	+ * Returns zero or a negative error (ie. ENOSPC, ENOMEM).
	380	+ */
	381	+int virtqueue_add_outbuf(struct virtqueue *vq,
	382	+ struct scatterlist sg[], unsigned int num,
	383	+ void *data,
	384	+ gfp_t gfp)
	385	+{
	386	+ return virtqueue_add(vq, &sg, sg_next_arr, num, 0, 1, 0, data, gfp);
	387	+}
	388	+EXPORT_SYMBOL_GPL(virtqueue_add_outbuf);
	389	+
	390	+/**
	391	+ * virtqueue_add_inbuf - expose input buffers to other end
	392	+ * @vq: the struct virtqueue we're talking about.
	393	+ * @sgs: array of scatterlists (need not be terminated!)
	394	+ * @num: the number of scatterlists writable by other side
	395	+ * @data: the token identifying the buffer.
	396	+ * @gfp: how to do memory allocations (if necessary).
	397	+ *
	398	+ * Caller must ensure we don't call this with other virtqueue operations
	399	+ * at the same time (except where noted).
	400	+ *
	401	+ * Returns zero or a negative error (ie. ENOSPC, ENOMEM).
	402	+ */
	403	+int virtqueue_add_inbuf(struct virtqueue *vq,
	404	+ struct scatterlist sg[], unsigned int num,
	405	+ void *data,
	406	+ gfp_t gfp)
	407	+{
	408	+ return virtqueue_add(vq, &sg, sg_next_arr, 0, num, 0, 1, data, gfp);
	409	+}
	410	+EXPORT_SYMBOL_GPL(virtqueue_add_inbuf);
	411	+
	412	+/**
369	413	* virtqueue_kick_prepare - first half of split virtqueue_kick call.
370	414	* @vq: the struct virtqueue
371	415	*
...	...	@@ -41,6 +41,16 @@
41	41	void *data,
42	42	gfp_t gfp);
43	43
	44	+int virtqueue_add_outbuf(struct virtqueue *vq,
	45	+ struct scatterlist sg[], unsigned int num,
	46	+ void *data,
	47	+ gfp_t gfp);
	48	+
	49	+int virtqueue_add_inbuf(struct virtqueue *vq,
	50	+ struct scatterlist sg[], unsigned int num,
	51	+ void *data,
	52	+ gfp_t gfp);
	53	+
44	54	int virtqueue_add_sgs(struct virtqueue *vq,
45	55	struct scatterlist *sgs[],
46	56	unsigned int out_sgs,