netdev - [PATCH net-next v2 01/12] net: add function dev_fetch_sw_netstats for fetching pcpu_sw

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Message-ID: <6d16a338-52f5-df69-0020-6bc771a7d498@gmail.com>
Date:   Mon, 12 Oct 2020 10:01:27 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Bjørn Mork <bjorn@...k.no>,
        Oliver Neukum <oneukum@...e.com>,
        Igor Mitsyanko <imitsyanko@...ntenna.com>,
        Sergey Matyukevich <geomatsi@...il.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <nikolay@...dia.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Johannes Berg <johannes@...solutions.net>,
        Pravin B Shelar <pshelar@....org>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        Herbert Xu <herbert@...dor.apana.org.au>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        linux-rdma@...r.kernel.org,
        Linux USB Mailing List <linux-usb@...r.kernel.org>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        bridge@...ts.linux-foundation.org
Subject: [PATCH net-next v2 01/12] net: add function dev_fetch_sw_netstats for
 fetching pcpu_sw_netstats

In several places the same code is used to populate rtnl_link_stats64
fields with data from pcpu_sw_netstats. Therefore factor out this code
to a new function dev_fetch_sw_netstats().

v2:
- constify argument netstats
- don't ignore netstats being NULL or an ERRPTR
- switch to EXPORT_SYMBOL_GPL

Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 include/linux/netdevice.h |  2 ++
 net/core/dev.c            | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index a0df43b13..fa1d8d624 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -4495,6 +4495,8 @@ struct rtnl_link_stats64 *dev_get_stats(struct net_device *dev,
 					struct rtnl_link_stats64 *storage);
 void netdev_stats_to_stats64(struct rtnl_link_stats64 *stats64,
 			     const struct net_device_stats *netdev_stats);
+void dev_fetch_sw_netstats(struct rtnl_link_stats64 *s,
+			   const struct pcpu_sw_netstats __percpu *netstats);
 
 extern int		netdev_max_backlog;
 extern int		netdev_tstamp_prequeue;
diff --git a/net/core/dev.c b/net/core/dev.c
index a146bac84..26bc10dec 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -10319,6 +10319,40 @@ struct rtnl_link_stats64 *dev_get_stats(struct net_device *dev,
 }
 EXPORT_SYMBOL(dev_get_stats);
 
+/**
+ *	dev_fetch_sw_netstats - get per-cpu network device statistics
+ *	@s: place to store stats
+ *	@netstats: per-cpu network stats to read from
+ *
+ *	Read per-cpu network statistics and populate the related fields in @s.
+ */
+void dev_fetch_sw_netstats(struct rtnl_link_stats64 *s,
+			   const struct pcpu_sw_netstats __percpu *netstats)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		const struct pcpu_sw_netstats *stats;
+		struct pcpu_sw_netstats tmp;
+		unsigned int start;
+
+		stats = per_cpu_ptr(netstats, cpu);
+		do {
+			start = u64_stats_fetch_begin_irq(&stats->syncp);
+			tmp.rx_packets = stats->rx_packets;
+			tmp.rx_bytes   = stats->rx_bytes;
+			tmp.tx_packets = stats->tx_packets;
+			tmp.tx_bytes   = stats->tx_bytes;
+		} while (u64_stats_fetch_retry_irq(&stats->syncp, start));
+
+		s->rx_packets += tmp.rx_packets;
+		s->rx_bytes   += tmp.rx_bytes;
+		s->tx_packets += tmp.tx_packets;
+		s->tx_bytes   += tmp.tx_bytes;
+	}
+}
+EXPORT_SYMBOL_GPL(dev_fetch_sw_netstats);
+
 struct netdev_queue *dev_ingress_queue_create(struct net_device *dev)
 {
 	struct netdev_queue *queue = dev_ingress_queue(dev);
-- 
2.28.0