[PATCH 13/19] virtio_ring: introduce virtqueue ops

[Jason Wang]

This patch introduces virtqueue ops which is a set of the callbacks
that will be called for different queue layout or features. This would
help to avoid branches for split/packed and will ease the future
implementation like in order.

Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
 drivers/virtio/virtio_ring.c | 96 +++++++++++++++++++++++++-----------
 1 file changed, 67 insertions(+), 29 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index a2884eae14d9..ce1dc90ee89d 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -159,9 +159,30 @@ struct vring_virtqueue_packed {
 	size_t event_size_in_bytes;
 };
 
+struct vring_virtqueue;
+
+struct virtqueue_ops {
+	int (*add)(struct vring_virtqueue *_vq, struct scatterlist *sgs[],
+		   unsigned int total_sg, unsigned int out_sgs,
+		   unsigned int in_sgs,	void *data,
+		   void *ctx, bool premapped, gfp_t gfp);
+	void *(*get)(struct vring_virtqueue *vq, unsigned int *len, void **ctx);
+	bool (*kick_prepare)(struct vring_virtqueue *vq);
+	void (*disable_cb)(struct vring_virtqueue *vq);
+	bool (*enable_cb_delayed)(struct vring_virtqueue *vq);
+	unsigned int (*enable_cb_prepare)(struct vring_virtqueue *vq);
+	bool (*poll)(const struct vring_virtqueue *vq, u16 last_used_idx);
+	void *(*detach_unused_buf)(struct vring_virtqueue *vq);
+	bool (*more_used)(const struct vring_virtqueue *vq);
+	int (*resize)(struct vring_virtqueue *vq, u32 num);
+	void (*reset)(struct vring_virtqueue *vq);
+};
+
 struct vring_virtqueue {
 	struct virtqueue vq;
 
+	struct virtqueue_ops *ops;
+
 	/* Is this a packed ring? */
 	bool packed_ring;
 
@@ -1116,6 +1137,8 @@ static int vring_alloc_queue_split(struct vring_virtqueue_split *vring_split,
 	return 0;
 }
 
+struct virtqueue_ops split_ops;
+
 static struct virtqueue *__vring_new_virtqueue_split(unsigned int index,
 					       struct vring_virtqueue_split *vring_split,
 					       struct virtio_device *vdev,
@@ -1134,6 +1157,7 @@ static struct virtqueue *__vring_new_virtqueue_split(unsigned int index,
 		return NULL;
 
 	vq->packed_ring = false;
+	vq->ops = &split_ops;
 	vq->vq.callback = callback;
 	vq->vq.vdev = vdev;
 	vq->vq.name = name;
@@ -2076,6 +2100,8 @@ static void virtqueue_reset_packed(struct vring_virtqueue *vq)
 	virtqueue_vring_init_packed(&vq->packed, !!vq->vq.callback);
 }
 
+struct virtqueue_ops packed_ops;
+
 static struct virtqueue *__vring_new_virtqueue_packed(unsigned int index,
 					       struct vring_virtqueue_packed *vring_packed,
 					       struct virtio_device *vdev,
@@ -2107,6 +2133,7 @@ static struct virtqueue *__vring_new_virtqueue_packed(unsigned int index,
 	vq->broken = false;
 #endif
 	vq->packed_ring = true;
+	vq->ops = &packed_ops;
 	vq->dma_dev = dma_dev;
 	vq->use_dma_api = vring_use_dma_api(vdev);
 
@@ -2194,6 +2221,34 @@ static int virtqueue_resize_packed(struct vring_virtqueue *vq, u32 num)
 	return -ENOMEM;
 }
 
+struct virtqueue_ops split_ops = {
+	.add = virtqueue_add_split,
+	.get = virtqueue_get_buf_ctx_split,
+	.kick_prepare = virtqueue_kick_prepare_split,
+	.disable_cb = virtqueue_disable_cb_split,
+	.enable_cb_delayed = virtqueue_enable_cb_delayed_split,
+	.enable_cb_prepare = virtqueue_enable_cb_prepare_split,
+	.poll = virtqueue_poll_split,
+	.detach_unused_buf = virtqueue_detach_unused_buf_split,
+	.more_used = more_used_split,
+	.resize = virtqueue_resize_split,
+	.reset = virtqueue_reset_split,
+};
+
+struct virtqueue_ops packed_ops = {
+	.add = virtqueue_add_packed,
+	.get = virtqueue_get_buf_ctx_packed,
+	.kick_prepare = virtqueue_kick_prepare_packed,
+	.disable_cb = virtqueue_disable_cb_packed,
+	.enable_cb_delayed = virtqueue_enable_cb_delayed_packed,
+	.enable_cb_prepare = virtqueue_enable_cb_prepare_packed,
+	.poll = virtqueue_poll_packed,
+	.detach_unused_buf = virtqueue_detach_unused_buf_packed,
+	.more_used = more_used_packed,
+	.resize = virtqueue_resize_packed,
+	.reset = virtqueue_reset_packed,
+};
+
 static int virtqueue_disable_and_recycle(struct virtqueue *_vq,
 					 void (*recycle)(struct virtqueue *vq, void *buf))
 {
@@ -2248,10 +2303,8 @@ static inline int virtqueue_add(struct virtqueue *_vq,
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
-	return vq->packed_ring ? virtqueue_add_packed(vq, sgs, total_sg,
-					out_sgs, in_sgs, data, ctx, premapped, gfp) :
-				 virtqueue_add_split(vq, sgs, total_sg,
-					out_sgs, in_sgs, data, ctx, premapped, gfp);
+	return vq->ops->add(vq, sgs, total_sg,
+			    out_sgs, in_sgs, data, ctx, premapped, gfp);
 }
 
 /**
@@ -2437,8 +2490,7 @@ bool virtqueue_kick_prepare(struct virtqueue *_vq)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
-	return vq->packed_ring ? virtqueue_kick_prepare_packed(vq) :
-				 virtqueue_kick_prepare_split(vq);
+	return vq->ops->kick_prepare(vq);
 }
 EXPORT_SYMBOL_GPL(virtqueue_kick_prepare);
 
@@ -2508,8 +2560,7 @@ void *virtqueue_get_buf_ctx(struct virtqueue *_vq, unsigned int *len,
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
-	return vq->packed_ring ? virtqueue_get_buf_ctx_packed(vq, len, ctx) :
-				 virtqueue_get_buf_ctx_split(vq, len, ctx);
+	return vq->ops->get(vq, len, ctx);
 }
 EXPORT_SYMBOL_GPL(virtqueue_get_buf_ctx);
 
@@ -2531,10 +2582,7 @@ void virtqueue_disable_cb(struct virtqueue *_vq)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
-	if (vq->packed_ring)
-		virtqueue_disable_cb_packed(vq);
-	else
-		virtqueue_disable_cb_split(vq);
+	return vq->ops->disable_cb(vq);
 }
 EXPORT_SYMBOL_GPL(virtqueue_disable_cb);
 
@@ -2557,8 +2605,7 @@ unsigned int virtqueue_enable_cb_prepare(struct virtqueue *_vq)
 	if (vq->event_triggered)
 		vq->event_triggered = false;
 
-	return vq->packed_ring ? virtqueue_enable_cb_prepare_packed(vq) :
-				 virtqueue_enable_cb_prepare_split(vq);
+	return vq->ops->enable_cb_prepare(vq);
 }
 EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare);
 
@@ -2579,8 +2626,7 @@ bool virtqueue_poll(struct virtqueue *_vq, unsigned int last_used_idx)
 		return false;
 
 	virtio_mb(vq->weak_barriers);
-	return vq->packed_ring ? virtqueue_poll_packed(vq, last_used_idx) :
-				 virtqueue_poll_split(vq, last_used_idx);
+	return vq->ops->poll(vq, last_used_idx);
 }
 EXPORT_SYMBOL_GPL(virtqueue_poll);
 
@@ -2623,8 +2669,7 @@ bool virtqueue_enable_cb_delayed(struct virtqueue *_vq)
 	if (vq->event_triggered)
 		vq->event_triggered = false;
 
-	return vq->packed_ring ? virtqueue_enable_cb_delayed_packed(vq) :
-				 virtqueue_enable_cb_delayed_split(vq);
+	return vq->ops->enable_cb_delayed(vq);
 }
 EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed);
 
@@ -2640,14 +2685,13 @@ void *virtqueue_detach_unused_buf(struct virtqueue *_vq)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
-	return vq->packed_ring ? virtqueue_detach_unused_buf_packed(vq) :
-				 virtqueue_detach_unused_buf_split(vq);
+	return vq->ops->detach_unused_buf(vq);
 }
 EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf);
 
 static inline bool more_used(const struct vring_virtqueue *vq)
 {
-	return vq->packed_ring ? more_used_packed(vq) : more_used_split(vq);
+	return vq->ops->more_used(vq);
 }
 
 /**
@@ -2785,10 +2829,7 @@ int virtqueue_resize(struct virtqueue *_vq, u32 num,
 	if (recycle_done)
 		recycle_done(_vq);
 
-	if (vq->packed_ring)
-		err = virtqueue_resize_packed(vq, num);
-	else
-		err = virtqueue_resize_split(vq, num);
+	err = vq->ops->resize(vq, num);
 
 	return virtqueue_enable_after_reset(_vq);
 }
@@ -2822,10 +2863,7 @@ int virtqueue_reset(struct virtqueue *_vq,
 	if (recycle_done)
 		recycle_done(_vq);
 
-	if (vq->packed_ring)
-		virtqueue_reset_packed(vq);
-	else
-		virtqueue_reset_split(vq);
+	vq->ops->reset(vq);
 
 	return virtqueue_enable_after_reset(_vq);
 }
-- 
2.42.0