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Subject[PATCH 5.4 131/135] net/mlx5: Fix sleep while atomic in mlx5_eswitch_get_vepa
Date
From: Huy Nguyen <huyn@mellanox.com>

commit 3d9c5e023a0dbf3e117bb416cfefd9405bf5af0c upstream.

rtnl_bridge_getlink is protected by rcu lock, so mlx5_eswitch_get_vepa
cannot take mutex lock. Two possible issues can happen:
1. User at the same time change vepa mode via RTM_SETLINK command.
2. User at the same time change the switchdev mode via devlink netlink
interface.

Case 1 cannot happen because rtnl executes one message in order.
Case 2 can happen but we do not expect user to change the switchdev mode
when changing vepa. Even if a user does it, so he will read a value
which is no longer valid.

Fixes: 8da202b24913 ("net/mlx5: E-Switch, Add support for VEPA in legacy mode.")
Signed-off-by: Huy Nguyen <huyn@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/ethernet/mellanox/mlx5/core/eswitch.c | 14 +++-----------
1 file changed, 3 insertions(+), 11 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
@@ -2319,25 +2319,17 @@ out:

int mlx5_eswitch_get_vepa(struct mlx5_eswitch *esw, u8 *setting)
{
- int err = 0;
-
if (!esw)
return -EOPNOTSUPP;

if (!ESW_ALLOWED(esw))
return -EPERM;

- mutex_lock(&esw->state_lock);
- if (esw->mode != MLX5_ESWITCH_LEGACY) {
- err = -EOPNOTSUPP;
- goto out;
- }
+ if (esw->mode != MLX5_ESWITCH_LEGACY)
+ return -EOPNOTSUPP;

*setting = esw->fdb_table.legacy.vepa_uplink_rule ? 1 : 0;
-
-out:
- mutex_unlock(&esw->state_lock);
- return err;
+ return 0;
}

int mlx5_eswitch_set_vport_trust(struct mlx5_eswitch *esw,

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