| From 47e26ff0c9eabfbe1f7e10e4197c308220e5d2b6 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Tue, 26 Aug 2025 17:54:56 +0200 |
| Subject: idpf: fix Rx descriptor ready check barrier in splitq |
| |
| From: Alexander Lobakin <aleksander.lobakin@intel.com> |
| |
| [ Upstream commit c20edbacc0295fd36f5f634b3421647ce3e08fd7 ] |
| |
| No idea what the current barrier position was meant for. At that point, |
| nothing is read from the descriptor, only the pointer to the actual one |
| is fetched. |
| The correct barrier usage here is after the generation check, so that |
| only the first qword is read if the descriptor is not yet ready and we |
| need to stop polling. Debatable on coherent DMA as the Rx descriptor |
| size is <= cacheline size, but anyway, the current barrier position |
| only makes the codegen worse. |
| |
| Fixes: 3a8845af66ed ("idpf: add RX splitq napi poll support") |
| Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com> |
| Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com> |
| Tested-by: Ramu R <ramu.r@intel.com> |
| Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/net/ethernet/intel/idpf/idpf_txrx.c | 8 ++------ |
| 1 file changed, 2 insertions(+), 6 deletions(-) |
| |
| diff --git a/drivers/net/ethernet/intel/idpf/idpf_txrx.c b/drivers/net/ethernet/intel/idpf/idpf_txrx.c |
| index eaad52a83b04c..50f90ed3107ec 100644 |
| --- a/drivers/net/ethernet/intel/idpf/idpf_txrx.c |
| +++ b/drivers/net/ethernet/intel/idpf/idpf_txrx.c |
| @@ -3187,18 +3187,14 @@ static int idpf_rx_splitq_clean(struct idpf_rx_queue *rxq, int budget) |
| /* get the Rx desc from Rx queue based on 'next_to_clean' */ |
| rx_desc = &rxq->rx[ntc].flex_adv_nic_3_wb; |
| |
| - /* This memory barrier is needed to keep us from reading |
| - * any other fields out of the rx_desc |
| - */ |
| - dma_rmb(); |
| - |
| /* if the descriptor isn't done, no work yet to do */ |
| gen_id = le16_get_bits(rx_desc->pktlen_gen_bufq_id, |
| VIRTCHNL2_RX_FLEX_DESC_ADV_GEN_M); |
| - |
| if (idpf_queue_has(GEN_CHK, rxq) != gen_id) |
| break; |
| |
| + dma_rmb(); |
| + |
| rxdid = FIELD_GET(VIRTCHNL2_RX_FLEX_DESC_ADV_RXDID_M, |
| rx_desc->rxdid_ucast); |
| if (rxdid != VIRTCHNL2_RXDID_2_FLEX_SPLITQ) { |
| -- |
| 2.51.0 |
| |
