Subject: [PATCH net-next 06/11] bnxt_en: Improve -ENOMEM logic in NAPI poll loop.

From: Michael Chan <[email-masked]>
Date: Mon, 28 Aug 2017 13:40:30 -0400

If we cannot allocate RX buffers in the NAPI poll loop when processing
an RX event, the current code does not count that event towards the NAPI
budget.  This can cause us to potentially loop forever in NAPI if we
consistently cannot allocate new buffers.  Improve it by counting
-ENOMEM event as 1 towards the NAPI budget.

Cc: Martin KaFai Lau <[email-masked]>
Signed-off-by: Michael Chan <[email-masked]>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 1afb408..a34fcdd 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -1850,6 +1850,13 @@ static int bnxt_poll_work(struct bnxt *bp, struct bnxt_napi *bnapi, int budget)
 							   &event);
 			if (likely(rc >= 0))
 				rx_pkts += rc;
+			/* Increment rx_pkts when rc is -ENOMEM to count towards
+			 * the NAPI budget.  Otherwise, we may potentially loop
+			 * here forever if we consistently cannot allocate
+			 * buffers.
+			 */
+			else if (rc == -ENOMEM)
+				rx_pkts++;
 			else if (rc == -EBUSY)	/* partial completion */
 				break;
 		} else if (unlikely((TX_CMP_TYPE(txcmp) ==
-- 
1.8.3.1