Re: [net-next,7/9] mlx5: psp: implement deferred tx key deletion

[Jakub Kicinski <kuba@kernel.org>]

This is an AI-generated review of your patch. The human sending this
email has considered the AI review valid, or at least plausible.

For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html
---
mlx5: psp: implement deferred tx key deletion

This patch implements the deferred tx key deletion API for mlx5. The
mlx5e_psp_tx_grace_begin() function records WQE counts on each tx queue,
and mlx5e_psp_tx_grace_end() returns success only after all tx queues
have advanced a full ring cycle past the snapshot point.

> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/psp.h b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/psp.h
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/psp.h
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/psp.h
> @@ -22,10 +22,17 @@ struct mlx5e_psp_stats {
>  	u64 psp_tx_bytes_drop;
>  };
>
> +struct mlx5e_psp_tx_snapshot {
> +	int num_channels;
> +	int num_tc;
> +	u64 wqes[];
> +};
> +
>  struct mlx5e_psp {
>  	struct psp_dev *psp;
>  	struct psp_dev_caps caps;
>  	struct mlx5e_psp_fs *fs;
> +	struct mlx5e_psp_tx_snapshot *tx_snapshot;
>  	atomic_t tx_key_cnt;
>  	atomic_t tx_drop;
>  };

Can the tx_snapshot allocation be leaked during device teardown?

If mlx5e_psp_tx_grace_begin() is called and allocates tx_snapshot, but
mlx5e_psp_cleanup() runs before mlx5e_psp_tx_grace_end() frees it:

    mlx5e_psp_cleanup()
        kfree(psp);   // psp->tx_snapshot not freed

The tx_snapshot memory would be leaked. Should mlx5e_psp_cleanup() free
psp->tx_snapshot before freeing psp?