patches for DPDK stable branches
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From: Shahaf Shuler <shahafs@mellanox.com>
To: adrien.mazarguil@6wind.com, nelio.laranjeiro@6wind.com
Cc: dev@dpdk.org, stable@dpdk.org
Subject: [dpdk-stable] [PATCH v3] net/mlx5: fix link status is always inconsist
Date: Tue, 31 Jan 2017 15:13:38 +0200	[thread overview]
Message-ID: <1485868418-44506-1-git-send-email-shahafs@mellanox.com> (raw)
In-Reply-To: <1485678163-17737-1-git-send-email-shahafs@mellanox.com>

Query the link status can end up in an inconsist state where the port is
down but it is reporting speed. For that another query is scheduled for a
later time.
A race condition is possible between the scheduled call and other link
status interrupt handlers. When the scheduled query by-pass those handlers,
the link status will be stuck in an in-consist state.
This patch addresses the race condition by not blocking link status
queries in case delayed query is on the flight.

Fixes: 198a3c339a8f ("mlx5: handle link status interrupts")
CC: stable@dpdk.org

Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
---
on v3:
* allow only single alarm on the flight.

on v2:
* change the commit log to better explain the race
* instead of blocking other interrupt handlers allow everyone to query the link status
---
 drivers/net/mlx5/mlx5_ethdev.c | 26 +++++++++++---------------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/drivers/net/mlx5/mlx5_ethdev.c b/drivers/net/mlx5/mlx5_ethdev.c
index e77238f..fcbe273 100644
--- a/drivers/net/mlx5/mlx5_ethdev.c
+++ b/drivers/net/mlx5/mlx5_ethdev.c
@@ -1128,7 +1128,7 @@ struct priv *
 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. */
@@ -1136,29 +1136,24 @@ struct priv *
 		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;
 }
@@ -1178,6 +1173,7 @@ struct priv *
 
 	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)
-- 
1.8.3.1

  reply	other threads:[~2017-01-31 13:13 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <485348339-43905-1-git-send-email-shahafs@mellanox.com>
2017-01-29  8:22 ` [dpdk-stable] [PATCH v2] " Shahaf Shuler
2017-01-31 13:13   ` Shahaf Shuler [this message]
2017-01-31 15:40     ` [dpdk-stable] [PATCH v3] " Nélio Laranjeiro
2017-02-01 10:57       ` [dpdk-stable] [dpdk-dev] " Ferruh Yigit
2017-01-29  8:28 ` [dpdk-stable] [PATCH v2] " Shahaf Shuler

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