From 49aaf57b22bdb72f649efe71b58dc4371d4b3b1b Mon Sep 17 00:00:00 2001
From: Aaro Koskinen <aaro.koskinen@nokia.com>
Date: Wed, 27 Mar 2019 22:35:37 +0200
Subject: [PATCH 01/22] net: stmmac: don't stop NAPI processing when dropping a
 packet
Git-commit: 07b3975352374c3f5ebb4a42ef0b253fe370542d
References: git-fixes
Patch-mainline: v5.1-rc4

Currently, if we drop a packet, we exit from NAPI loop before the budget
is consumed. In some situations this will make the RX processing stall
e.g. when flood pinging the system with oversized packets, as the
errorneous packets are not dropped efficiently.

If we drop a packet, we should just continue to the next one as long as
the budget allows.

Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Denis Kirjanov <denis.kirjanov@suse.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 4e8951065106..d1e2fb7a6afe 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3355,9 +3355,8 @@ static inline void stmmac_rx_refill(struct stmmac_priv *priv, u32 queue)
 static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 {
 	struct stmmac_rx_queue *rx_q = &priv->rx_queue[queue];
-	unsigned int entry = rx_q->cur_rx;
+	unsigned int next_entry = rx_q->cur_rx;
 	int coe = priv->hw->rx_csum;
-	unsigned int next_entry;
 	unsigned int count = 0;
 
 	if (netif_msg_rx_status(priv)) {
@@ -3372,10 +3371,12 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 		priv->hw->desc->display_ring(rx_head, DMA_RX_SIZE, true);
 	}
 	while (count < limit) {
-		int status;
+		int entry, status;
 		struct dma_desc *p;
 		struct dma_desc *np;
 
+		entry = next_entry;
+
 		if (priv->extend_desc)
 			p = (struct dma_desc *)(rx_q->dma_erx + entry);
 		else
@@ -3440,7 +3441,7 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 					   "len %d larger than size (%d)\n",
 					   frame_len, priv->dma_buf_sz);
 				priv->dev->stats.rx_length_errors++;
-				break;
+				continue;
 			}
 
 			/* ACS is set; GMAC core strips PAD/FCS for IEEE 802.3
@@ -3476,7 +3477,7 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 						dev_warn(priv->device,
 							 "packet dropped\n");
 					priv->dev->stats.rx_dropped++;
-					break;
+					continue;
 				}
 
 				dma_sync_single_for_cpu(priv->device,
@@ -3500,7 +3501,7 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 						   "%s: Inconsistent Rx chain\n",
 						   priv->dev->name);
 					priv->dev->stats.rx_dropped++;
-					break;
+					continue;
 				}
 				prefetch(skb->data - NET_IP_ALIGN);
 				rx_q->rx_skbuff[entry] = NULL;
@@ -3535,7 +3536,6 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
 			priv->dev->stats.rx_packets++;
 			priv->dev->stats.rx_bytes += frame_len;
 		}
-		entry = next_entry;
 	}
 
 	stmmac_rx_refill(priv, queue);
-- 
2.16.4