Re: [PATCH net 5/6] net/mlx5e: Fix deadlocks between devlink and netdev instance locks

[Jacob Keller]

On 2/12/2026 2:32 AM, Tariq Toukan wrote:
> From: Cosmin Ratiu <cratiu@xxxxxxxxxx>
>
> In the mentioned "Fixes" commit, various work tasks triggering devlink
> health reporter recovery were switched to use netdev_trylock to protect
> against concurrent tear down of the channels being recovered. But this
> had the side effect of introducing potential deadlocks because of
> incorrect lock ordering.
>
> The correct lock order is described by the init flow:
> probe_one -> mlx5_init_one (acquires devlink lock)
> -> mlx5_init_one_devl_locked -> mlx5_register_device
> -> mlx5_rescan_drivers_locked -...-> mlx5e_probe -> _mlx5e_probe
> -> register_netdev (acquires rtnl lock)
> -> register_netdevice (acquires netdev lock)
> => devlink lock -> rtnl lock -> netdev lock.
>
> But in the current recovery flow, the order is wrong:
> mlx5e_tx_err_cqe_work (acquires netdev lock)
> -> mlx5e_reporter_tx_err_cqe -> mlx5e_health_report
> -> devlink_health_report (acquires devlink lock => boom!)
> -> devlink_health_reporter_recover
> -> mlx5e_tx_reporter_recover -> mlx5e_tx_reporter_recover_from_ctx
> -> mlx5e_tx_reporter_err_cqe_recover
>
> The same pattern exists in:
> mlx5e_reporter_rx_timeout
> mlx5e_reporter_tx_ptpsq_unhealthy
> mlx5e_reporter_tx_timeout
>
> Fix these by moving the netdev_trylock calls from the work handlers
> lower in the call stack, in the respective recovery functions, where
> they are actually necessary.
>
> Fixes: 8f7b00307bf1 ("net/mlx5e: Convert mlx5 netdevs to instance locking")
> Signed-off-by: Cosmin Ratiu <cratiu@xxxxxxxxxx>
> Reviewed-by: Dragos Tatulea <dtatulea@xxxxxxxxxx>
> Signed-off-by: Tariq Toukan <tariqt@xxxxxxxxxx>
> ---

Reviewed-by: Jacob Keller <jacob.e.keller@xxxxxxxxx>