releases/4.19.103/net-mvneta-move-rx_dropped-and-rx_errors-in-per-cpu-stats.patch

From foo@baz Sun 09 Feb 2020 10:56:46 PM CET
From: Lorenzo Bianconi <lorenzo@kernel.org>
Date: Thu, 6 Feb 2020 10:14:39 +0100
Subject: net: mvneta: move rx_dropped and rx_errors in per-cpu stats

From: Lorenzo Bianconi <lorenzo@kernel.org>

[ Upstream commit c35947b8ff8acca33134ee39c31708233765c31a ]

Move rx_dropped and rx_errors counters in mvneta_pcpu_stats in order to
avoid possible races updating statistics

Fixes: 562e2f467e71 ("net: mvneta: Improve the buffer allocation method for SWBM")
Fixes: dc35a10f68d3 ("net: mvneta: bm: add support for hardware buffer management")
Fixes: c5aff18204da ("net: mvneta: driver for Marvell Armada 370/XP network unit")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/marvell/mvneta.c |   27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -385,6 +385,8 @@ struct mvneta_pcpu_stats {
 	struct	u64_stats_sync syncp;
 	u64	rx_packets;
 	u64	rx_bytes;
+	u64	rx_dropped;
+	u64	rx_errors;
 	u64	tx_packets;
 	u64	tx_bytes;
 };
@@ -701,6 +703,8 @@ mvneta_get_stats64(struct net_device *de
 		struct mvneta_pcpu_stats *cpu_stats;
 		u64 rx_packets;
 		u64 rx_bytes;
+		u64 rx_dropped;
+		u64 rx_errors;
 		u64 tx_packets;
 		u64 tx_bytes;
 
@@ -709,19 +713,20 @@ mvneta_get_stats64(struct net_device *de
 			start = u64_stats_fetch_begin_irq(&cpu_stats->syncp);
 			rx_packets = cpu_stats->rx_packets;
 			rx_bytes   = cpu_stats->rx_bytes;
+			rx_dropped = cpu_stats->rx_dropped;
+			rx_errors  = cpu_stats->rx_errors;
 			tx_packets = cpu_stats->tx_packets;
 			tx_bytes   = cpu_stats->tx_bytes;
 		} while (u64_stats_fetch_retry_irq(&cpu_stats->syncp, start));
 
 		stats->rx_packets += rx_packets;
 		stats->rx_bytes   += rx_bytes;
+		stats->rx_dropped += rx_dropped;
+		stats->rx_errors  += rx_errors;
 		stats->tx_packets += tx_packets;
 		stats->tx_bytes   += tx_bytes;
 	}
 
-	stats->rx_errors	= dev->stats.rx_errors;
-	stats->rx_dropped	= dev->stats.rx_dropped;
-
 	stats->tx_dropped	= dev->stats.tx_dropped;
 }
 
@@ -1698,8 +1703,14 @@ static u32 mvneta_txq_desc_csum(int l3_o
 static void mvneta_rx_error(struct mvneta_port *pp,
 			    struct mvneta_rx_desc *rx_desc)
 {
+	struct mvneta_pcpu_stats *stats = this_cpu_ptr(pp->stats);
 	u32 status = rx_desc->status;
 
+	/* update per-cpu counter */
+	u64_stats_update_begin(&stats->syncp);
+	stats->rx_errors++;
+	u64_stats_update_end(&stats->syncp);
+
 	switch (status & MVNETA_RXD_ERR_CODE_MASK) {
 	case MVNETA_RXD_ERR_CRC:
 		netdev_err(pp->dev, "bad rx status %08x (crc error), size=%d\n",
@@ -1960,7 +1971,6 @@ static int mvneta_rx_swbm(struct napi_st
 			/* Check errors only for FIRST descriptor */
 			if (rx_status & MVNETA_RXD_ERR_SUMMARY) {
 				mvneta_rx_error(pp, rx_desc);
-				dev->stats.rx_errors++;
 				/* leave the descriptor untouched */
 				continue;
 			}
@@ -1971,11 +1981,17 @@ static int mvneta_rx_swbm(struct napi_st
 			skb_size = max(rx_copybreak, rx_header_size);
 			rxq->skb = netdev_alloc_skb_ip_align(dev, skb_size);
 			if (unlikely(!rxq->skb)) {
+				struct mvneta_pcpu_stats *stats = this_cpu_ptr(pp->stats);
+
 				netdev_err(dev,
 					   "Can't allocate skb on queue %d\n",
 					   rxq->id);
-				dev->stats.rx_dropped++;
+
 				rxq->skb_alloc_err++;
+
+				u64_stats_update_begin(&stats->syncp);
+				stats->rx_dropped++;
+				u64_stats_update_end(&stats->syncp);
 				continue;
 			}
 			copy_size = min(skb_size, rx_bytes);
@@ -2135,7 +2151,6 @@ err_drop_frame_ret_pool:
 			mvneta_bm_pool_put_bp(pp->bm_priv, bm_pool,
 					      rx_desc->buf_phys_addr);
 err_drop_frame:
-			dev->stats.rx_errors++;
 			mvneta_rx_error(pp, rx_desc);
 			/* leave the descriptor untouched */
 			continue;