4.4-stable review patch. If anyone has any objections, please let me know.
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From: Michael Chan michael.chan@broadcom.com
[ Upstream commit 73f21c653f930f438d53eed29b5e4c65c8a0f906 ]
The current netpoll implementation in the bnxt_en driver has problems that may miss TX completion events. bnxt_poll_work() in effect is only handling at most 1 TX packet before exiting. In addition, there may be in flight TX completions that ->poll() may miss even after we fix bnxt_poll_work() to handle all visible TX completions. netpoll may not call ->poll() again and HW may not generate IRQ because the driver does not ARM the IRQ when the budget (0 for netpoll) is reached.
We fix it by handling all TX completions and to always ARM the IRQ when we exit ->poll() with 0 budget.
Also, the logic to ACK the completion ring in case it is almost filled with TX completions need to be adjusted to take care of the 0 budget case, as discussed with Eric Dumazet edumazet@google.com
Reported-by: Song Liu songliubraving@fb.com Reviewed-by: Song Liu songliubraving@fb.com Tested-by: Song Liu songliubraving@fb.com Signed-off-by: Michael Chan michael.chan@broadcom.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/ethernet/broadcom/bnxt/bnxt.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c @@ -1343,8 +1343,11 @@ static int bnxt_poll_work(struct bnxt *b if (TX_CMP_TYPE(txcmp) == CMP_TYPE_TX_L2_CMP) { tx_pkts++; /* return full budget so NAPI will complete. */ - if (unlikely(tx_pkts > bp->tx_wake_thresh)) + if (unlikely(tx_pkts > bp->tx_wake_thresh)) { rx_pkts = budget; + raw_cons = NEXT_RAW_CMP(raw_cons); + break; + } } else if ((TX_CMP_TYPE(txcmp) & 0x30) == 0x10) { rc = bnxt_rx_pkt(bp, bnapi, &raw_cons, &agg_event); if (likely(rc >= 0)) @@ -1362,7 +1365,7 @@ static int bnxt_poll_work(struct bnxt *b } raw_cons = NEXT_RAW_CMP(raw_cons);
- if (rx_pkts == budget) + if (rx_pkts && rx_pkts == budget) break; }
@@ -1404,8 +1407,12 @@ static int bnxt_poll(struct napi_struct while (1) { work_done += bnxt_poll_work(bp, bnapi, budget - work_done);
- if (work_done >= budget) + if (work_done >= budget) { + if (!budget) + BNXT_CP_DB_REARM(cpr->cp_doorbell, + cpr->cp_raw_cons); break; + }
if (!bnxt_has_work(bp, cpr)) { napi_complete(napi);