linux-kernel - [PATCH net-next 3/6] net: mvneta: discriminate error cause for missed packet

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Date:   Fri,  6 Jul 2018 15:19:46 +0200
From:   Gregory CLEMENT <gregory.clement@...tlin.com>
To:     "David S. Miller" <davem@...emloft.net>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Cc:     Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        linux-arm-kernel@...ts.infradead.org,
        Jason Cooper <jason@...edaemon.net>,
        Andrew Lunn <andrew@...n.ch>,
        Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
        Gregory CLEMENT <gregory.clement@...tlin.com>,
        Yelena Krivosheev <yelena@...vell.com>,
        Nadav Haklai <nadavh@...vell.com>,
        Marcin Wojtas <mw@...ihalf.com>,
        Dmitri Epshtein <dima@...vell.com>,
        Antoine Tenart <antoine.tenart@...tlin.com>,
        Miquèl Raynal <miquel.raynal@...tlin.com>,
        Maxime Chevallier <maxime.chevallier@...tlin.com>
Subject: [PATCH net-next 3/6] net: mvneta: discriminate error cause for missed packet

From: Yelena Krivosheev <yelena@...vell.com>

In order to improve the diagnostic in case of error, make the distinction
between refill error and skb allocation error.

Signed-off-by: Yelena Krivosheev <yelena@...vell.com>
[gregory: extract from a larger patch]
Signed-off-by: Gregory CLEMENT <gregory.clement@...tlin.com>
---
 drivers/net/ethernet/marvell/mvneta.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index 531227e2e48e..2c575c6732ce 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -589,9 +589,6 @@ struct mvneta_rx_queue {
 	/* num of rx descriptors in the rx descriptor ring */
 	int size;
 
-	/* counter of times when mvneta_refill() failed */
-	int missed;
-
 	u32 pkts_coal;
 	u32 time_coal;
 
@@ -609,6 +606,10 @@ struct mvneta_rx_queue {
 
 	/* Index of the next RX DMA descriptor to process */
 	int next_desc_to_proc;
+
+	/* error counters */
+	u32 skb_alloc_err;
+	u32 refill_err;
 };
 
 static enum cpuhp_state online_hpstate;
@@ -1946,8 +1947,13 @@ static int mvneta_rx_swbm(struct mvneta_port *pp, int rx_todo,
 		if (rx_bytes <= rx_copybreak) {
 		/* better copy a small frame and not unmap the DMA region */
 			skb = netdev_alloc_skb_ip_align(dev, rx_bytes);
-			if (unlikely(!skb))
+			if (unlikely(!skb)) {
+				netdev_err(dev,
+					   "Can't allocate skb on queue %d\n",
+					   rxq->id);
+				rxq->skb_alloc_err++;
 				goto err_drop_frame;
+			}
 
 			dma_sync_single_range_for_cpu(dev->dev.parent,
 						      phys_addr,
@@ -1972,7 +1978,7 @@ static int mvneta_rx_swbm(struct mvneta_port *pp, int rx_todo,
 		err = mvneta_rx_refill(pp, rx_desc, rxq);
 		if (err) {
 			netdev_err(dev, "Linux processing - Can't refill\n");
-			rxq->missed++;
+			rxq->refill_err++;
 			goto err_drop_frame;
 		}
 
@@ -2102,7 +2108,7 @@ static int mvneta_rx_hwbm(struct mvneta_port *pp, int rx_todo,
 		err = hwbm_pool_refill(&bm_pool->hwbm_pool, GFP_ATOMIC);
 		if (err) {
 			netdev_err(dev, "Linux processing - Can't refill\n");
-			rxq->missed++;
+			rxq->refill_err++;
 			goto err_drop_frame_ret_pool;
 		}
 
-- 
2.17.1