[dpdk-dev] [PATCH v2 6/7] virtio: Resolve for control queue

[Ouyang Changchun]

Control queue can't work for vhost-user mulitple queue mode,
so introduce a counter to void the dead loop when polling the control queue.

Changes in v2:
  - fix checkpatch errors

Signed-off-by: Changchun Ouyang <changchun.ouyang at intel.com>
---
 drivers/net/virtio/virtio_ethdev.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/net/virtio/virtio_ethdev.c 
b/drivers/net/virtio/virtio_ethdev.c
index f74e413..9618f4f 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -61,6 +61,7 @@
 #include "virtio_logs.h"
 #include "virtqueue.h"

+#define CQ_POLL_COUNTER 500 /* Avoid dead loop when polling control queue */

 static int eth_virtio_dev_init(struct rte_eth_dev *eth_dev);
 static int  virtio_dev_configure(struct rte_eth_dev *dev);
@@ -118,6 +119,7 @@ virtio_send_command(struct virtqueue *vq, struct 
virtio_pmd_ctrl *ctrl,
        int k, sum = 0;
        virtio_net_ctrl_ack status = ~0;
        struct virtio_pmd_ctrl result;
+       uint32_t cq_poll = CQ_POLL_COUNTER;

        ctrl->status = status;

@@ -177,9 +179,15 @@ virtio_send_command(struct virtqueue *vq, struct 
virtio_pmd_ctrl *ctrl,
        virtqueue_notify(vq);

        rte_rmb();
-       while (vq->vq_used_cons_idx == vq->vq_ring.used->idx) {
+
+       /**
+        * FIXME: The control queue doesn't work for vhost-user
+        * multiple queue, introduce poll_ms to avoid the deadloop.
+        */
+       while ((vq->vq_used_cons_idx == vq->vq_ring.used->idx) && (cq_poll != 
0)) {
                rte_rmb();
                usleep(100);
+               cq_poll--;
        }

        while (vq->vq_used_cons_idx != vq->vq_ring.used->idx) {
@@ -207,7 +215,10 @@ virtio_send_command(struct virtqueue *vq, struct 
virtio_pmd_ctrl *ctrl,
        PMD_INIT_LOG(DEBUG, "vq->vq_free_cnt=%d\nvq->vq_desc_head_idx=%d",
                        vq->vq_free_cnt, vq->vq_desc_head_idx);

-       memcpy(&result, vq->virtio_net_hdr_mz->addr,
+       if (cq_poll == 0)
+               result.status = 0;
+       else
+               memcpy(&result, vq->virtio_net_hdr_mz->addr,
                        sizeof(struct virtio_pmd_ctrl));

        return result.status;
-- 
1.8.4.2