netdev - [PATCH net-next 1/8] bnxt_en: Handle all NQ notifications in bnxt_poll

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Message-Id: <1583707554-1163-2-git-send-email-michael.chan@broadcom.com>
Date:   Sun,  8 Mar 2020 18:45:47 -0400
From:   Michael Chan <michael.chan@...adcom.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org
Subject: [PATCH net-next 1/8] bnxt_en: Handle all NQ notifications in bnxt_poll_p5().

In bnxt_poll_p5(), the logic polls for up to 2 completion rings (RX and
TX) for work.  In the current code, if we reach budget polling the
first completion ring, we will stop.  If the other completion ring
has work to do, we will handle it when NAPI calls us back.

This is not optimal.  We potentially leave an unproceesed entry in
the NQ.  When we are finally done with NAPI polling and re-enable
interrupt, the remaining entry in the NQ will cause interrupt to
be triggered immediately for no reason.

Modify the code in bnxt_poll_p5() to keep looping until all NQ
entries are handled even if the first completion ring has reached
budget.

Signed-off-by: Michael Chan <michael.chan@...adcom.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index dee13ee..0b1af02 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -2438,6 +2438,9 @@ static int bnxt_poll_p5(struct napi_struct *napi, int budget)
 		nqcmp = &cpr->nq_desc_ring[CP_RING(cons)][CP_IDX(cons)];

 		if (!NQ_CMP_VALID(nqcmp, raw_cons)) {
+			if (cpr->has_more_work)
+				break;
+
 			__bnxt_poll_cqs_done(bp, bnapi, DBR_TYPE_CQ_ARMALL,
 					     false);
 			cpr->cp_raw_cons = raw_cons;
@@ -2459,13 +2462,11 @@ static int bnxt_poll_p5(struct napi_struct *napi, int budget)
 			cpr2 = cpr->cp_ring_arr[idx];
 			work_done += __bnxt_poll_work(bp, cpr2,
 						      budget - work_done);
-			cpr->has_more_work = cpr2->has_more_work;
+			cpr->has_more_work |= cpr2->has_more_work;
 		} else {
 			bnxt_hwrm_handler(bp, (struct tx_cmp *)nqcmp);
 		}
 		raw_cons = NEXT_RAW_CMP(raw_cons);
-		if (cpr->has_more_work)
-			break;
 	}
 	__bnxt_poll_cqs_done(bp, bnapi, DBR_TYPE_CQ, true);
 	cpr->cp_raw_cons = raw_cons;
-- 
2.5.1