[SRU X] [PATCH 1/1] UBUNTU: SAUCE: bnxt_en_bpo: Fix TX timeout during netpoll

[Nivedita Singhvi]

From: Michael Chan <michael.chan at broadcom.com>

BugLink: http://bugs.launchpad.net/bugs/1814095

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 at google.com>

Reported-by: Song Liu <songliubraving at fb.com>
Reviewed-by: Song Liu <songliubraving at fb.com>
Tested-by: Song Liu <songliubraving at fb.com>
Signed-off-by: Michael Chan <michael.chan at broadcom.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
(backported from commit 73f21c653f930f438d53eed29b5e4c65c8a0f906
 upstream)
Signed-off-by: Nivedita Singhvi <nivedita.singhvi at canonical.com>


diff --git a/ubuntu/bnxt/bnxt.c b/ubuntu/bnxt/bnxt.c
index f04db69..9b51120 100644
--- a/ubuntu/bnxt/bnxt.c
+++ b/ubuntu/bnxt/bnxt.c
@@ -2006,8 +2006,11 @@ static int bnxt_poll_work(struct bnxt *bp, struct
bnxt_napi *bnapi, int budget)
 		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) {
 			if (likely(budget))
 				rc = bnxt_rx_pkt(bp, bnapi, &raw_cons, &event);
@@ -2028,7 +2031,7 @@ 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;
 	}

@@ -2156,8 +2159,12 @@ 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)) {
 #ifdef HAVE_NEW_NAPI_COMPLETE_DONE