[PATCH AUTOSEL 5.5 019/121] net/mlx5: E-Switch, Hold mutex when querying drop counter in legacy mode

Sasha Levin
2020-04-11T23:40:09Z

From: Bodong Wang <bodong@mellanox.com>

[ Upstream commit 14c844cbf3503076de6e2e48d575216f1600b19f ]

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@mellanox.com>
Reviewed-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 07282c679dcdf..d92e11e9343f5 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
@@ -2597,9 +2597,13 @@ 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);
@@ -2610,20 +2614,22 @@ 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,
--
2.20.1