A rmb() is required to ensure that the CQE is not read before it is written by the adapter DMA. PCI ordering rules will make sure the other fields are written before the marker at the end of struct eth_fast_path_rx_cqe but without rmb() a weakly ordered processor can process stale data. Without the barrier we have observed various crashes including bnx2x_tpa_start being called on queues not stopped (resulting in message start of bin not in stop) and NULL pointer exceptions from bnx2x_rx_int. Signed-off-by: Milton Miller Signed-off-by: Wen Xiong --- drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) Index: b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c =================================================================== --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c 2014-05-23 10:34:21.000000000 -0500 +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c 2014-06-03 11:55:56.747765400 -0500 @@ -906,6 +906,18 @@ static int bnx2x_rx_int(struct bnx2x_fas bd_prod = RX_BD(bd_prod); bd_cons = RX_BD(bd_cons); + /* A rmb() is required to ensure that the CQE is not read + * before it is written by the adapter DMA. PCI ordering + * rules will make sure the other fields are written before + * the marker at the end of struct eth_fast_path_rx_cqe + * but without rmb() a weakly ordered processor can process + * stale data. Without the barrier TPA state-machine might + * enter inconsistent state and kernel stack might be + * provided with incorrect packet description - these lead + * to various kernel crashed. + */ + rmb(); + cqe_fp_flags = cqe_fp->type_error_flags; cqe_fp_type = cqe_fp_flags & ETH_FAST_PATH_RX_CQE_TYPE; -- -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html