From 4d6acb62d2db5c1cc533c9a0b6e418ef9f63642e Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 8 Dec 2015 05:54:40 -0800 Subject: [PATCH] bnx2x: avoid soft lockup in bnx2x_poll() Under heavy TX load, bnx2x_poll() can loop forever and trigger soft lockup bugs. A napi poll handler must yield after one TX completion round, risk of livelock is too high otherwise. Bug is very easy to trigger using a debug build, and udp flood, because of added cpu cycles in TX completion, and we do not receive enough packets to break the loop. Reported-by: Willem de Bruijn Signed-off-by: Eric Dumazet Cc: Ariel Elior Signed-off-by: David S. Miller --- .../net/ethernet/broadcom/bnx2x/bnx2x_cmn.c | 51 ++++++++----------- 1 file changed, 21 insertions(+), 30 deletions(-) diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c index f6634a524153..d7cc2aa7c37a 100644 --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c @@ -3204,42 +3204,32 @@ int bnx2x_set_power_state(struct bnx2x *bp, pci_power_t state) */ static int bnx2x_poll(struct napi_struct *napi, int budget) { - int work_done = 0; - u8 cos; struct bnx2x_fastpath *fp = container_of(napi, struct bnx2x_fastpath, napi); struct bnx2x *bp = fp->bp; + int rx_work_done; + u8 cos; - while (1) { #ifdef BNX2X_STOP_ON_ERROR - if (unlikely(bp->panic)) { - napi_complete(napi); - return 0; - } + if (unlikely(bp->panic)) { + napi_complete(napi); + return 0; + } #endif - for_each_cos_in_tx_queue(fp, cos) - if (bnx2x_tx_queue_has_work(fp->txdata_ptr[cos])) - bnx2x_tx_int(bp, fp->txdata_ptr[cos]); - - if (bnx2x_has_rx_work(fp)) { - work_done += bnx2x_rx_int(fp, budget - work_done); - - /* must not complete if we consumed full budget */ - if (work_done >= budget) - break; - } + for_each_cos_in_tx_queue(fp, cos) + if (bnx2x_tx_queue_has_work(fp->txdata_ptr[cos])) + bnx2x_tx_int(bp, fp->txdata_ptr[cos]); - /* Fall out from the NAPI loop if needed */ - if (!(bnx2x_has_rx_work(fp) || bnx2x_has_tx_work(fp))) { + rx_work_done = (bnx2x_has_rx_work(fp)) ? bnx2x_rx_int(fp, budget) : 0; - /* No need to update SB for FCoE L2 ring as long as - * it's connected to the default SB and the SB - * has been updated when NAPI was scheduled. - */ - if (IS_FCOE_FP(fp)) { - napi_complete(napi); - break; - } + if (rx_work_done < budget) { + /* No need to update SB for FCoE L2 ring as long as + * it's connected to the default SB and the SB + * has been updated when NAPI was scheduled. + */ + if (IS_FCOE_FP(fp)) { + napi_complete(napi); + } else { bnx2x_update_fpsb_idx(fp); /* bnx2x_has_rx_work() reads the status block, * thus we need to ensure that status block indices @@ -3264,12 +3254,13 @@ static int bnx2x_poll(struct napi_struct *napi, int budget) bnx2x_ack_sb(bp, fp->igu_sb_id, USTORM_ID, le16_to_cpu(fp->fp_hc_idx), IGU_INT_ENABLE, 1); - break; + } else { + rx_work_done = budget; } } } - return work_done; + return rx_work_done; } /* we split the first BD into headers and data BDs -- 2.20.1