netdev - Re: [PATCH net-next 2/4] eth: mlx4: don't try to complete XDP frames in netpoll

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Message-ID: <d0f7e1e3-2e30-4d10-9535-cd264dcef5fc@gmail.com>
Date: Thu, 6 Feb 2025 21:50:56 +0200
From: Tariq Toukan <ttoukan.linux@...il.com>
To: Jakub Kicinski <kuba@...nel.org>, davem@...emloft.net
Cc: netdev@...r.kernel.org, edumazet@...gle.com, pabeni@...hat.com,
 andrew+netdev@...n.ch, horms@...nel.org, tariqt@...dia.com, hawk@...nel.org
Subject: Re: [PATCH net-next 2/4] eth: mlx4: don't try to complete XDP frames
 in netpoll



On 05/02/2025 5:12, Jakub Kicinski wrote:
> mlx4 doesn't support xdp xmit

Are you referring to xdp_redirect egress?

mlx4 supports XDP_TX ("bounce"), as well as XDP_DROP, XDP_PASS, and 
XDP_REDIRECT.

 > and wasn't using page pool> until now, so it could run XDP 
completions in netpoll
> (NAPI budget == 0) just fine. Page pool has calling
> context requirements, make sure we don't try to call
> it from what is potentially HW IRQ context.
> 
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>
> ---
>   drivers/net/ethernet/mellanox/mlx4/en_tx.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
> index 1ddb11cb25f9..6e077d202827 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
> @@ -450,6 +450,8 @@ int mlx4_en_process_tx_cq(struct net_device *dev,
>   
>   	if (unlikely(!priv->port_up))
>   		return 0;
> +	if (unlikely(!napi_budget) && cq->type == TX_XDP)
> +		return 0;
>   
>   	netdev_txq_bql_complete_prefetchw(ring->tx_queue);
>