Re: [PATCH net v2 3/3] octeontx2-pf: Do xdp_do_flush() after redirects.

[Kui-Feng Lee <sinquersw@xxxxxxxxx>]

On 9/18/23 08:36, Sebastian Andrzej Siewior wrote:
> xdp_do_flush() should be invoked before leaving the NAPI poll function
> if XDP-redirect has been performed.
>
> Invoke xdp_do_flush() before leaving NAPI.
>
> Cc: Geetha sowjanya <gakula@xxxxxxxxxxx>
> Cc: Subbaraya Sundeep <sbhatta@xxxxxxxxxxx>
> Cc: Sunil Goutham <sgoutham@xxxxxxxxxxx>
> Cc: hariprasad <hkelam@xxxxxxxxxxx>
> Fixes: 06059a1a9a4a5 ("octeontx2-pf: Add XDP support to netdev PF")
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> Acked-by: Geethasowjanya Akula <gakula@xxxxxxxxxxx>
> ---
>   .../marvell/octeontx2/nic/otx2_txrx.c         | 19 +++++++++++++------
>   1 file changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
> index e77d438489557..53b2a4ef52985 100644
> --- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
> +++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_txrx.c
> @@ -29,7 +29,8 @@
>   static bool otx2_xdp_rcv_pkt_handler(struct otx2_nic *pfvf,
>   				     struct bpf_prog *prog,
>   				     struct nix_cqe_rx_s *cqe,
> -				     struct otx2_cq_queue *cq);
> +				     struct otx2_cq_queue *cq,
> +				     bool *need_xdp_flush);
>   
>   static int otx2_nix_cq_op_status(struct otx2_nic *pfvf,
>   				 struct otx2_cq_queue *cq)
> @@ -337,7 +338,7 @@ static bool otx2_check_rcv_errors(struct otx2_nic *pfvf,
>   static void otx2_rcv_pkt_handler(struct otx2_nic *pfvf,
>   				 struct napi_struct *napi,
>   				 struct otx2_cq_queue *cq,
> -				 struct nix_cqe_rx_s *cqe)
> +				 struct nix_cqe_rx_s *cqe, bool *need_xdp_flush)
>   {
>   	struct nix_rx_parse_s *parse = &cqe->parse;
>   	struct nix_rx_sg_s *sg = &cqe->sg;
> @@ -353,7 +354,7 @@ static void otx2_rcv_pkt_handler(struct otx2_nic *pfvf,
>   	}
>   
>   	if (pfvf->xdp_prog)
> -		if (otx2_xdp_rcv_pkt_handler(pfvf, pfvf->xdp_prog, cqe, cq))
> +		if (otx2_xdp_rcv_pkt_handler(pfvf, pfvf->xdp_prog, cqe, cq, need_xdp_flush))
>   			return;
>   
>   	skb = napi_get_frags(napi);
> @@ -388,6 +389,7 @@ static int otx2_rx_napi_handler(struct otx2_nic *pfvf,
>   				struct napi_struct *napi,
>   				struct otx2_cq_queue *cq, int budget)
>   {
> +	bool need_xdp_flush = false;
>   	struct nix_cqe_rx_s *cqe;
>   	int processed_cqe = 0;
>   
> @@ -409,13 +411,15 @@ static int otx2_rx_napi_handler(struct otx2_nic *pfvf,
>   		cq->cq_head++;
>   		cq->cq_head &= (cq->cqe_cnt - 1);
>   
> -		otx2_rcv_pkt_handler(pfvf, napi, cq, cqe);
> +		otx2_rcv_pkt_handler(pfvf, napi, cq, cqe, &need_xdp_flush);
>   
>   		cqe->hdr.cqe_type = NIX_XQE_TYPE_INVALID;
>   		cqe->sg.seg_addr = 0x00;
>   		processed_cqe++;
>   		cq->pend_cqe--;
>   	}
> +	if (need_xdp_flush)
> +		xdp_do_flush();
>   
>   	/* Free CQEs to HW */
>   	otx2_write64(pfvf, NIX_LF_CQ_OP_DOOR,
> @@ -1354,7 +1358,8 @@ bool otx2_xdp_sq_append_pkt(struct otx2_nic *pfvf, u64 iova, int len, u16 qidx)
>   static bool otx2_xdp_rcv_pkt_handler(struct otx2_nic *pfvf,
>   				     struct bpf_prog *prog,
>   				     struct nix_cqe_rx_s *cqe,
> -				     struct otx2_cq_queue *cq)
> +				     struct otx2_cq_queue *cq,
> +				     bool *need_xdp_flush)
>   {
>   	unsigned char *hard_start, *data;
>   	int qidx = cq->cq_idx;
> @@ -1391,8 +1396,10 @@ static bool otx2_xdp_rcv_pkt_handler(struct otx2_nic *pfvf,
>   
>   		otx2_dma_unmap_page(pfvf, iova, pfvf->rbsize,
>   				    DMA_FROM_DEVICE);
> -		if (!err)
> +		if (!err) {
> +			*need_xdp_flush = true;

Is it possible to call xdp_do_flush() at the first place (here)?

>   			return true;
> +		}
>   		put_page(page);
>   		break;
>   	default: