net/mlx5: fix inconsistent link status

Querying the link status can end up being in an inconsistent state,
like the port is reporting speed although it is down.

For this case another query is scheduled.

A race condition can occur between the scheduled query and link
status interrupt handlers.

When the scheduled query by-pass interrupt handlers, the link status
will be stuck in an inconsistent state.

This patch addresses the race condition by not blocking link status
queries in case delayed query is used.

Fixes: 198a3c339a8f ("mlx5: handle link status interrupts")
Cc: stable@dpdk.org
Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
Acked-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>

diff --git a/drivers/net/mlx5/mlx5_ethdev.c b/drivers/net/mlx5/mlx5_ethdev.c
index a46526e..de9d102 100644 (file)
--- a/drivers/net/mlx5/mlx5_ethdev.c
+++ b/drivers/net/mlx5/mlx5_ethdev.c
@@ -1125,7 +1125,7 @@ static int
 priv_dev_link_status_handler(struct priv *priv, struct rte_eth_dev *dev)
 {
        struct ibv_async_event event;
-       int port_change = 0;
+       struct rte_eth_link *link = &dev->data->dev_link;
        int ret = 0;
 
        /* Read all message and acknowledge them. */
@@ -1133,29 +1133,24 @@ priv_dev_link_status_handler(struct priv *priv, struct rte_eth_dev *dev)
                if (ibv_get_async_event(priv->ctx, &event))
                        break;
 
-               if (event.event_type == IBV_EVENT_PORT_ACTIVE ||
-                   event.event_type == IBV_EVENT_PORT_ERR)
-                       port_change = 1;
-               else
+               if (event.event_type != IBV_EVENT_PORT_ACTIVE &&
+                   event.event_type != IBV_EVENT_PORT_ERR)
                        DEBUG("event type %d on port %d not handled",
                              event.event_type, event.element.port_num);
                ibv_ack_async_event(&event);
        }
-
-       if (port_change ^ priv->pending_alarm) {
-               struct rte_eth_link *link = &dev->data->dev_link;
-
-               priv->pending_alarm = 0;
-               mlx5_link_update(dev, 0);
-               if (((link->link_speed == 0) && link->link_status) ||
-                   ((link->link_speed != 0) && !link->link_status)) {
+       mlx5_link_update(dev, 0);
+       if (((link->link_speed == 0) && link->link_status) ||
+           ((link->link_speed != 0) && !link->link_status)) {
+               if (!priv->pending_alarm) {
                        /* Inconsistent status, check again later. */
                        priv->pending_alarm = 1;
                        rte_eal_alarm_set(MLX5_ALARM_TIMEOUT_US,
                                          mlx5_dev_link_status_handler,
                                          dev);
-               } else
-                       ret = 1;
+               }
+       } else {
+               ret = 1;
        }
        return ret;
 }
@@ -1175,6 +1170,7 @@ mlx5_dev_link_status_handler(void *arg)
 
        priv_lock(priv);
        assert(priv->pending_alarm == 1);
+       priv->pending_alarm = 0;
        ret = priv_dev_link_status_handler(priv, dev);
        priv_unlock(priv);
        if (ret)