RE: [PATCH net-next,V3, 2/3] net: mana: Add support for RX CQE Coalescing

[Haiyang Zhang]

> -----Original Message-----
> From: Haiyang Zhang <haiyangz@xxxxxxxxxxxxxxxxxxx>
> Sent: Friday, March 6, 2026 6:19 PM
> To: linux-hyperv@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; KY Srinivasan
> <kys@xxxxxxxxxxxxx>; Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>; Wei Liu
> <wei.liu@xxxxxxxxxx>; Dexuan Cui <DECUI@xxxxxxxxxxxxx>; Long Li
> <longli@xxxxxxxxxxxxx>; Andrew Lunn <andrew+netdev@xxxxxxx>; David S.
> Miller <davem@xxxxxxxxxxxxx>; Eric Dumazet <edumazet@xxxxxxxxxx>; Jakub
> Kicinski <kuba@xxxxxxxxxx>; Paolo Abeni <pabeni@xxxxxxxxxx>; Konstantin
> Taranov <kotaranov@xxxxxxxxxxxxx>; Simon Horman <horms@xxxxxxxxxx>; Erni
> Sri Satya Vennela <ernis@xxxxxxxxxxxxxxxxxxx>; Shradha Gupta
> <shradhagupta@xxxxxxxxxxxxxxxxxxx>; Dipayaan Roy
> <dipayanroy@xxxxxxxxxxxxxxxxxxx>; Shiraz Saleem
> <shirazsaleem@xxxxxxxxxxxxx>; Kees Cook <kees@xxxxxxxxxx>; Subbaraya
> Sundeep <sbhatta@xxxxxxxxxxx>; Breno Leitao <leitao@xxxxxxxxxx>; Aditya
> Garg <gargaditya@xxxxxxxxxxxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx;
> linux-rdma@xxxxxxxxxxxxxxx
> Cc: Paul Rosswurm <paulros@xxxxxxxxxxxxx>
> Subject: [PATCH net-next,V3, 2/3] net: mana: Add support for RX CQE
> Coalescing
> 
> From: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>

> @@ -2112,13 +2122,16 @@ static void mana_process_rx_cqe(struct mana_rxq
> *rxq, struct mana_cq *cq,
>  		++ndev->stats.rx_dropped;
>  		rxbuf_oob = &rxq->rx_oobs[rxq->buf_index];
>  		netdev_warn_once(ndev, "Dropped a truncated packet\n");
> -		goto drop;
> 
> -	case CQE_RX_COALESCED_4:
> -		netdev_err(ndev, "RX coalescing is unsupported\n");
> -		apc->eth_stats.rx_coalesced_err++;
> +		mana_move_wq_tail(rxq->gdma_rq,
> +				  rxbuf_oob->wqe_inf.wqe_size_in_bu);
> +		mana_post_pkt_rxq(rxq);
>  		return;
> 
> +	case CQE_RX_COALESCED_4:
> +		coalesced = true;
> +		break;
> +
>  	case CQE_RX_OBJECT_FENCE:
>  		complete(&rxq->fence_event);
>  		return;
> @@ -2130,30 +2143,36 @@ static void mana_process_rx_cqe(struct mana_rxq
> *rxq, struct mana_cq *cq,
>  		return;
>  	}
> 
> -	pktlen = oob->ppi[0].pkt_len;
> +	for (i = 0; i < MANA_RXCOMP_OOB_NUM_PPI; i++) {
> +		pktlen = oob->ppi[i].pkt_len;
> +		if (pktlen == 0) {
> +			if (i == 0)
> +				netdev_err_once(
> +					ndev,
> +					"RX pkt len=0, rq=%u, cq=%u,
> rxobj=0x%llx\n",
> +					rxq->gdma_id, cq->gdma_id, rxq->rxobj);
> +			break;
> +		}
> 
> -	if (pktlen == 0) {
> -		/* data packets should never have packetlength of zero */
> -		netdev_err(ndev, "RX pkt len=0, rq=%u, cq=%u, rxobj=0x%llx\n",
> -			   rxq->gdma_id, cq->gdma_id, rxq->rxobj);
> -		return;
> -	}
> +		curr = rxq->buf_index;
> +		rxbuf_oob = &rxq->rx_oobs[curr];
> +		WARN_ON_ONCE(rxbuf_oob->wqe_inf.wqe_size_in_bu != 1);
> 
> -	curr = rxq->buf_index;
> -	rxbuf_oob = &rxq->rx_oobs[curr];
> -	WARN_ON_ONCE(rxbuf_oob->wqe_inf.wqe_size_in_bu != 1);
> +		mana_refill_rx_oob(dev, rxq, rxbuf_oob, &old_buf, &old_fp);
> 
> -	mana_refill_rx_oob(dev, rxq, rxbuf_oob, &old_buf, &old_fp);
> +		/* Unsuccessful refill will have old_buf == NULL.
> +		 * In this case, mana_rx_skb() will drop the packet.
> +		 */
> +		mana_rx_skb(old_buf, old_fp, oob, rxq, i);
> 
> -	/* Unsuccessful refill will have old_buf == NULL.
> -	 * In this case, mana_rx_skb() will drop the packet.
> -	 */
> -	mana_rx_skb(old_buf, old_fp, oob, rxq);
> +		mana_move_wq_tail(rxq->gdma_rq,
> +				  rxbuf_oob->wqe_inf.wqe_size_in_bu);

I will fix this pointed out by AI review:

> The comment says "Unsuccessful refill will have old_buf == NULL" but this is
> only true for the first iteration.
> Should old_buf be set to NULL at the top of the loop, before calling
> mana_refill_rx_oob()?