net/mlx5e: Fix potential deadlock by deferring RX timeout recovery

mlx5e_reporter_rx_timeout() is currently invoked synchronously
in the driver's open error flow. This causes the thread holding
priv->state_lock to attempt acquiring the devlink lock, which
can result in a circular dependency with other devlink operations.

For example:

- Devlink health diagnose flow:
  - __devlink_nl_pre_doit() acquires the devlink lock.
  - devlink_nl_health_reporter_diagnose_doit() invokes the
    driver's diagnose callback.
  - mlx5e_rx_reporter_diagnose() then attempts to acquire
    priv->state_lock.

- Driver open flow:
  - mlx5e_open() acquires priv->state_lock.
  - If an error occurs, devlink_health_reporter may be called,
    attempting to acquire the devlink lock.

To prevent this circular locking scenario, defer the RX timeout
recovery by scheduling it via a workqueue. This ensures that the
recovery work acquires locks in a consistent order: first the
devlink lock, then priv->state_lock.

Additionally, make the recovery work acquire the netdev instance
lock to safely synchronize with the open/close channel flows,
similar to mlx5e_tx_timeout_work. Repeatedly attempt to acquire
the netdev instance lock until it is taken or the target RQ is no
longer active, as indicated by the MLX5E_STATE_CHANNELS_ACTIVE bit.

Fixes: 32c57fb26863 ("net/mlx5e: Report and recover from rx timeout")
Signed-off-by: Shahar Shitrit <shshitrit@nvidia.com>
Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/1753256672-337784-4-git-send-email-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions