[PATCH v3 2/2] examples/vhost: unconfigure DMA vchannel

[xuan.ding@intel.com]

From: Xuan Ding <xuan.ding@intel.com>

This patch applies rte_vhost_async_dma_unconfigure() API
to manually free DMA vchannels instead of waiting
until the program ends to be released.

Signed-off-by: Xuan Ding <xuan.ding@intel.com>
---
 examples/vhost/main.c | 45 ++++++++++++++++++++++++++++++-------------
 examples/vhost/main.h |  1 +
 2 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/examples/vhost/main.c b/examples/vhost/main.c
index 0fa4753e70..32f396d88a 100644
--- a/examples/vhost/main.c
+++ b/examples/vhost/main.c
@@ -1558,6 +1558,28 @@ vhost_clear_queue(struct vhost_dev *vdev, uint16_t queue_id)
 	}
 }
 
+static void
+vhost_clear_async(struct vhost_dev *vdev, int vid, uint16_t queue_id)
+{
+	int16_t dma_id;
+	uint16_t ref_count;
+
+	if (dma_bind[vid].dmas[queue_id].async_enabled) {
+		vhost_clear_queue(vdev, queue_id);
+		rte_vhost_async_channel_unregister(vid, queue_id);
+		dma_bind[vid].dmas[queue_id].async_enabled = false;
+	}
+
+	dma_id = dma_bind[vid2socketid[vdev->vid]].dmas[queue_id].dev_id;
+	dma_bind[vid2socketid[vdev->vid]].dmas[queue_id].dma_ref_count--;
+	ref_count = dma_bind[vid2socketid[vdev->vid]].dmas[queue_id].dma_ref_count;
+
+	if (ref_count == 0 && dma_id != INVALID_DMA_ID) {
+		if (rte_vhost_async_dma_unconfigure(dma_id, 0) < 0)
+			RTE_LOG(ERR, VHOST_PORT, "Failed to unconfigure DMA in vhost.\n");
+	}
+}
+
 /*
  * Remove a device from the specific data core linked list and from the
  * main linked list. Synchronization  occurs through the use of the
@@ -1614,17 +1636,8 @@ destroy_device(int vid)
 		"(%d) device has been removed from data core\n",
 		vdev->vid);
 
-	if (dma_bind[vid].dmas[VIRTIO_RXQ].async_enabled) {
-		vhost_clear_queue(vdev, VIRTIO_RXQ);
-		rte_vhost_async_channel_unregister(vid, VIRTIO_RXQ);
-		dma_bind[vid].dmas[VIRTIO_RXQ].async_enabled = false;
-	}
-
-	if (dma_bind[vid].dmas[VIRTIO_TXQ].async_enabled) {
-		vhost_clear_queue(vdev, VIRTIO_TXQ);
-		rte_vhost_async_channel_unregister(vid, VIRTIO_TXQ);
-		dma_bind[vid].dmas[VIRTIO_TXQ].async_enabled = false;
-	}
+	vhost_clear_async(vdev, vid, VIRTIO_RXQ);
+	vhost_clear_async(vdev, vid, VIRTIO_TXQ);
 
 	rte_free(vdev);
 }
@@ -1673,14 +1686,19 @@ vhost_async_channel_register(int vid)
 
 	if (dma_bind[vid2socketid[vid]].dmas[VIRTIO_RXQ].dev_id != INVALID_DMA_ID) {
 		rx_ret = rte_vhost_async_channel_register(vid, VIRTIO_RXQ);
-		if (rx_ret == 0)
+		if (rx_ret == 0) {
 			dma_bind[vid2socketid[vid]].dmas[VIRTIO_RXQ].async_enabled = true;
+			dma_bind[vid2socketid[vid]].dmas[VIRTIO_RXQ].dma_ref_count++;
+		}
+
 	}
 
 	if (dma_bind[vid2socketid[vid]].dmas[VIRTIO_TXQ].dev_id != INVALID_DMA_ID) {
 		tx_ret = rte_vhost_async_channel_register(vid, VIRTIO_TXQ);
-		if (tx_ret == 0)
+		if (tx_ret == 0) {
 			dma_bind[vid2socketid[vid]].dmas[VIRTIO_TXQ].async_enabled = true;
+			dma_bind[vid2socketid[vid]].dmas[VIRTIO_TXQ].dma_ref_count++;
+		}
 	}
 
 	return rx_ret | tx_ret;
@@ -1886,6 +1904,7 @@ reset_dma(void)
 		for (j = 0; j < RTE_MAX_QUEUES_PER_PORT * 2; j++) {
 			dma_bind[i].dmas[j].dev_id = INVALID_DMA_ID;
 			dma_bind[i].dmas[j].async_enabled = false;
+			dma_bind[i].dmas[j].dma_ref_count = 0;
 		}
 	}
 
diff --git a/examples/vhost/main.h b/examples/vhost/main.h
index 2fcb8376c5..2b2cf828d3 100644
--- a/examples/vhost/main.h
+++ b/examples/vhost/main.h
@@ -96,6 +96,7 @@ struct dma_info {
 	struct rte_pci_addr addr;
 	int16_t dev_id;
 	bool async_enabled;
+	uint16_t dma_ref_count;
 };
 
 struct dma_for_vhost {
-- 
2.17.1