netdev - [PATCH net RFT] bnxt_en: Fix TX timeout during netpoll.

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Message-Id: <1537911099-4073-1-git-send-email-michael.chan@broadcom.com>
Date:   Tue, 25 Sep 2018 17:31:39 -0400
From:   Michael Chan <michael.chan@...adcom.com>
To:     songliubraving@...com, edumazet@...gle.com, davem@...emloft.net
Cc:     netdev@...r.kernel.org
Subject: [PATCH net RFT] bnxt_en: Fix TX timeout during netpoll.

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.

Reported-by: Song Liu <songliubraving@...com>
Signed-off-by: Michael Chan <michael.chan@...adcom.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 61957b0..c981b53 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -1913,7 +1913,7 @@ static int bnxt_poll_work(struct bnxt *bp, struct bnxt_napi *bnapi, int budget)
 		}
 		raw_cons = NEXT_RAW_CMP(raw_cons);

-		if (rx_pkts == budget)
+		if (rx_pkts && rx_pkts == budget)
 			break;
 	}

@@ -2027,8 +2027,12 @@ static int bnxt_poll(struct napi_struct *napi, int budget)
 	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)) {
 			if (napi_complete_done(napi, work_done))
-- 
2.5.1