[dpdk-dev] [PATCH v2 11/19] vhost: introduce new API to export queue free entries

[Yuanhan Liu <yuanhan.liu@linux.intel.com>]

The new API rte_vhost_avail_entries() is actually a rename of
rte_vring_available_entries(), with the "vring" to "vhost" name
change to keep the consistency of other vhost exported APIs.

This change could let us avoid the dependency of "virtio_net"
struct, to prepare for the ABI refactoring.

Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
---
 doc/guides/rel_notes/release_16_07.rst |  2 ++
 examples/vhost/main.c                  |  4 ++--
 lib/librte_vhost/rte_vhost_version.map |  1 +
 lib/librte_vhost/rte_virtio_net.h      | 24 +++++++++++++-----------
 lib/librte_vhost/virtio-net.c          | 17 +++++++++++++++++
 5 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/doc/guides/rel_notes/release_16_07.rst b/doc/guides/rel_notes/release_16_07.rst
index f6d543c..d293eda 100644
--- a/doc/guides/rel_notes/release_16_07.rst
+++ b/doc/guides/rel_notes/release_16_07.rst
@@ -97,6 +97,8 @@ This section should contain API changes. Sample format:
   ibadcrc, ibadlen, imcasts, fdirmatch, fdirmiss,
   tx_pause_xon, rx_pause_xon, tx_pause_xoff, rx_pause_xoff.
 
+* ``rte_vring_available_entries`` is renamed to ``rte_vhost_avail_entries``.
+
 
 ABI Changes
 -----------
diff --git a/examples/vhost/main.c b/examples/vhost/main.c
index cb04585..67ef0ad 100644
--- a/examples/vhost/main.c
+++ b/examples/vhost/main.c
@@ -1055,13 +1055,13 @@ drain_eth_rx(struct vhost_dev *vdev)
 	 * to diminish packet loss.
 	 */
 	if (enable_retry &&
-	    unlikely(rx_count > rte_vring_available_entries(dev,
+	    unlikely(rx_count > rte_vhost_avail_entries(dev->vid,
 			VIRTIO_RXQ))) {
 		uint32_t retry;
 
 		for (retry = 0; retry < burst_rx_retry_num; retry++) {
 			rte_delay_us(burst_rx_delay_time);
-			if (rx_count <= rte_vring_available_entries(dev,
+			if (rx_count <= rte_vhost_avail_entries(dev->vid,
 					VIRTIO_RXQ))
 				break;
 		}
diff --git a/lib/librte_vhost/rte_vhost_version.map b/lib/librte_vhost/rte_vhost_version.map
index 4608e3b..93f1188 100644
--- a/lib/librte_vhost/rte_vhost_version.map
+++ b/lib/librte_vhost/rte_vhost_version.map
@@ -24,6 +24,7 @@ DPDK_2.1 {
 DPDK_16.07 {
 	global:
 
+	rte_vhost_avail_entries;
 	rte_vhost_get_ifname;
 	rte_vhost_get_numa_node;
 	rte_vhost_get_queue_num;
diff --git a/lib/librte_vhost/rte_virtio_net.h b/lib/librte_vhost/rte_virtio_net.h
index 0898e8b..0427461 100644
--- a/lib/librte_vhost/rte_virtio_net.h
+++ b/lib/librte_vhost/rte_virtio_net.h
@@ -184,17 +184,6 @@ struct virtio_net_device_ops {
 	int (*vring_state_changed)(struct virtio_net *dev, uint16_t queue_id, int enable);	/**< triggered when a vring is enabled or disabled */
 };
 
-static inline uint16_t __attribute__((always_inline))
-rte_vring_available_entries(struct virtio_net *dev, uint16_t queue_id)
-{
-	struct vhost_virtqueue *vq = dev->virtqueue[queue_id];
-
-	if (!vq->enabled)
-		return 0;
-
-	return *(volatile uint16_t *)&vq->avail->idx - vq->last_used_idx_res;
-}
-
 /**
  * Function to convert guest physical addresses to vhost virtual addresses.
  * This is used to convert guest virtio buffer addresses.
@@ -285,6 +274,19 @@ uint32_t rte_vhost_get_queue_num(int vid);
 int rte_vhost_get_ifname(int vid, char *buf, size_t len);
 
 /**
+ * Get how many avail entries are left in the queue
+ *
+ * @param vid
+ *  virtio-net device ID
+ * @param queue_id
+ *  virtio queue index
+ *
+ * @return
+ *  num of avail entires left
+ */
+uint16_t rte_vhost_avail_entries(int vid, uint16_t queue_id);
+
+/**
  * This function adds buffers to the virtio devices RX virtqueue. Buffers can
  * be received from the physical port or from another virtual device. A packet
  * count is returned to indicate the number of packets that were succesfully
diff --git a/lib/librte_vhost/virtio-net.c b/lib/librte_vhost/virtio-net.c
index 375c9d4..115eba4 100644
--- a/lib/librte_vhost/virtio-net.c
+++ b/lib/librte_vhost/virtio-net.c
@@ -783,6 +783,23 @@ rte_vhost_get_ifname(int vid, char *buf, size_t len)
 	return 0;
 }
 
+uint16_t
+rte_vhost_avail_entries(int vid, uint16_t queue_id)
+{
+	struct virtio_net *dev;
+	struct vhost_virtqueue *vq;
+
+	dev = get_device(vid);
+	if (!dev)
+		return 0;
+
+	vq = dev->virtqueue[queue_id];
+	if (!vq->enabled)
+		return 0;
+
+	return *(volatile uint16_t *)&vq->avail->idx - vq->last_used_idx_res;
+}
+
 int rte_vhost_enable_guest_notification(struct virtio_net *dev,
 	uint16_t queue_id, int enable)
 {
-- 
1.9.0