6.17-stable review patch. If anyone has any objections, please let me know.
------------------
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) {