netdev - [net-next 02/14] net/mlx5: E-Switch, Hold mutex when querying drop counter in legacy mode

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Message-Id: <20200314011622.64939-3-saeedm@mellanox.com>
Date:   Fri, 13 Mar 2020 18:16:10 -0700
From:   Saeed Mahameed <saeedm@...lanox.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     kuba@...nel.org, netdev@...r.kernel.org,
        Bodong Wang <bodong@...lanox.com>,
        Parav Pandit <parav@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: [net-next 02/14] net/mlx5: E-Switch, Hold mutex when querying drop counter in legacy mode

From: Bodong Wang <bodong@...lanox.com>

Consider scenario below, CPU 1 is at risk to query already destroyed
drop counters. Need to apply the same state mutex when disabling vport.

+-------------------------------+-------------------------------------+
| CPU 0                         | CPU 1                               |
+-------------------------------+-------------------------------------+
| mlx5_device_disable_sriov     | mlx5e_get_vf_stats                  |
| mlx5_eswitch_disable          | mlx5_eswitch_get_vport_stats        |
| esw_disable_vport             | mlx5_eswitch_query_vport_drop_stats |
| mlx5_fc_destroy(drop_counter) | mlx5_fc_query(drop_counter)         |
+-------------------------------+-------------------------------------+

Fixes: b8a0dbe3a90b ("net/mlx5e: E-switch, Add steering drop counters")
Signed-off-by: Bodong Wang <bodong@...lanox.com>
Reviewed-by: Parav Pandit <parav@...lanox.com>
Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/eswitch.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
index b123089866e2..b4b93d2322a9 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
@@ -2620,9 +2620,13 @@ static int mlx5_eswitch_query_vport_drop_stats(struct mlx5_core_dev *dev,
 	u64 bytes = 0;
 	int err = 0;
 
-	if (!vport->enabled || esw->mode != MLX5_ESWITCH_LEGACY)
+	if (esw->mode != MLX5_ESWITCH_LEGACY)
 		return 0;
 
+	mutex_lock(&esw->state_lock);
+	if (!vport->enabled)
+		goto unlock;
+
 	if (vport->egress.legacy.drop_counter)
 		mlx5_fc_query(dev, vport->egress.legacy.drop_counter,
 			      &stats->rx_dropped, &bytes);
@@ -2633,20 +2637,22 @@ static int mlx5_eswitch_query_vport_drop_stats(struct mlx5_core_dev *dev,
 
 	if (!MLX5_CAP_GEN(dev, receive_discard_vport_down) &&
 	    !MLX5_CAP_GEN(dev, transmit_discard_vport_down))
-		return 0;
+		goto unlock;
 
 	err = mlx5_query_vport_down_stats(dev, vport->vport, 1,
 					  &rx_discard_vport_down,
 					  &tx_discard_vport_down);
 	if (err)
-		return err;
+		goto unlock;
 
 	if (MLX5_CAP_GEN(dev, receive_discard_vport_down))
 		stats->rx_dropped += rx_discard_vport_down;
 	if (MLX5_CAP_GEN(dev, transmit_discard_vport_down))
 		stats->tx_dropped += tx_discard_vport_down;
 
-	return 0;
+unlock:
+	mutex_unlock(&esw->state_lock);
+	return err;
 }
 
 int mlx5_eswitch_get_vport_stats(struct mlx5_eswitch *esw,
-- 
2.24.1