RE: [Intel-wired-lan] [PATCH net v2 3/3] net: stmmac: skip queueMaxSDU check for AF_XDP

> -----Original Message-----
> From: Intel-wired-lan <[email protected]> On Behalf
> Of Stanislav Fomichev
> Sent: Thursday, August 13, 2026 9:08 PM
> To: [email protected]
> Cc: [email protected]; [email protected]; [email protected];
> [email protected]; Nguyen, Anthony L <[email protected]>;
> Kitszel, Przemyslaw <[email protected]>;
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]; [email protected]; Lobakin,
> Aleksander <[email protected]>; [email protected]; Karlsson,
> Magnus <[email protected]>; Fijalkowski, Maciej
> <[email protected]>; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; Song, Yoong Siang
> <[email protected]>; G Thomas, Rohan
> <[email protected]>; [email protected]; linux-
> [email protected]; [email protected]; linux-stm32@st-md-
> mailman.stormreply.com; [email protected];
> [email protected]; [email protected]
> Subject: [Intel-wired-lan] [PATCH net v2 3/3] net: stmmac: skip
> queueMaxSDU check for AF_XDP
> 
> Commit c5c3e1bfc9e0 ("net: stmmac: Offload queueMaxSDU from tc-
> taprio") was inspired by commit 92a0dcb8427d ("igc: offload queue max
> SDU from tc-taprio"), but the igc change does not apply the check to
> AF_XDP.
> 
> xsk_tx_peek_desc() reserves a completion entry. Continuing without
> queuing or completing the descriptor leaves the AF_XDP rings
> imbalanced, so remove the check from the zero-copy path.
> 
> The assumptions is that AF_XDP zero-copy traffic bypasses the qdisc,
' The assumptions is' -> ' The assumption is'

Reviewed-by: Aleksandr Loktionov <[email protected]>

> so taprio's queueMaxSDU check does not apply to this path.
> 
> Fixes: c5c3e1bfc9e0 ("net: stmmac: Offload queueMaxSDU from tc-
> taprio")
> Signed-off-by: Stanislav Fomichev <[email protected]>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 7 -------
>  1 file changed, 7 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 62de03e65a90..4a82f4351303 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -2710,13 +2710,6 @@ static bool stmmac_xdp_xmit_zc(struct
> stmmac_priv *priv, u32 queue, u32 budget)
>  		if (!xsk_tx_peek_desc(pool, &xdp_desc))
>  			break;
> 
> -		if (priv->est && priv->est->enable &&
> -		    priv->est->max_sdu[queue] &&
> -		    xdp_desc.len > priv->est->max_sdu[queue]) {
> -			priv->xstats.max_sdu_txq_drop[queue]++;
> -			continue;
> -		}
> -
>  		tx_desc = stmmac_get_tx_desc(priv, tx_q, entry);
>  		dma_addr = xsk_buff_raw_get_dma(pool, xdp_desc.addr);
>  		meta = xsk_buff_get_metadata(pool, xdp_desc.addr,
> --
> 2.53.0-Meta