net/mlx5: link status update separation

Link status is sometimes inconsistent during a LSC event.
When it occurs, the PMD refrains from immediately notifying
the application; instead, an alarm is scheduled to check
link status later and notify the application once it has settled.

In the previous code the alarm callback calls to the interrupt
handler for link status recheck and may cause to unnecessary
interrupt events check.

This patch separates the link status update and the interrupt event
handler to avoid the unnecessary check and arranges the interrupt
handler for more interrupt supports in the future.

Comment was added in the new function to explain the inconsistent
link status reason.

Signed-off-by: Matan Azrad <matan@mellanox.com>
Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>

diff --git a/drivers/net/mlx5/mlx5_ethdev.c b/drivers/net/mlx5/mlx5_ethdev.c
index 53a23ab..eef403f 100644 (file)
--- a/drivers/net/mlx5/mlx5_ethdev.c
+++ b/drivers/net/mlx5/mlx5_ethdev.c
@@ -1113,47 +1113,74 @@ mlx5_ibv_device_to_pci_addr(const struct ibv_device *device,
 }
 
 /**
- * Link status handler.
+ * Update the link status.
  *
  * @param priv
  *   Pointer to private structure.
- * @param dev
- *   Pointer to the rte_eth_dev structure.
  *
  * @return
- *   Nonzero if the callback process can be called immediately.
+ *   Zero if the callback process can be called immediately.
  */
 static int
-priv_dev_link_status_handler(struct priv *priv, struct rte_eth_dev *dev)
+priv_link_status_update(struct priv *priv)
+{
+       struct rte_eth_link *link = &priv->dev->data->dev_link;
+
+       mlx5_link_update(priv->dev, 0);
+       if (((link->link_speed == 0) && link->link_status) ||
+               ((link->link_speed != 0) && !link->link_status)) {
+               /*
+                * Inconsistent status. Event likely occurred before the
+                * kernel netdevice exposes the new status.
+                */
+               if (!priv->pending_alarm) {
+                       priv->pending_alarm = 1;
+                       rte_eal_alarm_set(MLX5_ALARM_TIMEOUT_US,
+                                         mlx5_dev_link_status_handler,
+                                         priv->dev);
+               }
+               return 1;
+       } else if (unlikely(priv->pending_alarm)) {
+               /* Link interrupt occurred while alarm is already scheduled. */
+               priv->pending_alarm = 0;
+               rte_eal_alarm_cancel(mlx5_dev_link_status_handler, priv->dev);
+       }
+       return 0;
+}
+
+/**
+ * Device status handler.
+ *
+ * @param priv
+ *   Pointer to private structure.
+ * @param events
+ *   Pointer to event flags holder.
+ *
+ * @return
+ *   Events bitmap of callback process which can be called immediately.
+ */
+static uint32_t
+priv_dev_status_handler(struct priv *priv)
 {
        struct ibv_async_event event;
-       struct rte_eth_link *link = &dev->data->dev_link;
-       int ret = 0;
+       uint32_t ret = 0;
 
        /* Read all message and acknowledge them. */
        for (;;) {
                if (ibv_get_async_event(priv->ctx, &event))
                        break;
-
-               if (event.event_type != IBV_EVENT_PORT_ACTIVE &&
-                   event.event_type != IBV_EVENT_PORT_ERR)
+               if ((event.event_type == IBV_EVENT_PORT_ACTIVE ||
+                       event.event_type == IBV_EVENT_PORT_ERR) &&
+                       (priv->dev->data->dev_conf.intr_conf.lsc == 1))
+                       ret |= (1 << RTE_ETH_EVENT_INTR_LSC);
+               else
                        DEBUG("event type %d on port %d not handled",
                              event.event_type, event.element.port_num);
                ibv_ack_async_event(&event);
        }
-       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;
-       }
+       if (ret & (1 << RTE_ETH_EVENT_INTR_LSC))
+               if (priv_link_status_update(priv))
+                       ret &= ~(1 << RTE_ETH_EVENT_INTR_LSC);
        return ret;
 }
 
@@ -1173,9 +1200,9 @@ 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);
+       ret = priv_link_status_update(priv);
        priv_unlock(priv);
-       if (ret)
+       if (!ret)
                _rte_eth_dev_callback_process(dev, RTE_ETH_EVENT_INTR_LSC, NULL,
                                              NULL);
 }
@@ -1193,12 +1220,12 @@ mlx5_dev_interrupt_handler(void *cb_arg)
 {
        struct rte_eth_dev *dev = cb_arg;
        struct priv *priv = dev->data->dev_private;
-       int ret;
+       uint32_t events;
 
        priv_lock(priv);
-       ret = priv_dev_link_status_handler(priv, dev);
+       events = priv_dev_status_handler(priv);
        priv_unlock(priv);
-       if (ret)
+       if (events & (1 << RTE_ETH_EVENT_INTR_LSC))
                _rte_eth_dev_callback_process(dev, RTE_ETH_EVENT_INTR_LSC, NULL,
                                              NULL);
 }