[PATCH 27/30] backports: Add dev_fetch_sw_netstats()

Add the dev_fetch_sw_netstats which was added in commit 44fa32f008ab
("net: add function dev_fetch_sw_netstats for fetching
pcpu_sw_netstats") in kernel 5.10. This is used by qmi_wwan, usbnet,
qtnfmac and mac80211.

Signed-off-by: Hauke Mehrtens <[email protected]>
---
 backport/backport-include/linux/netdevice.h |  4 +++
 backport/compat/backport-5.10.c             | 34 +++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/backport/backport-include/linux/netdevice.h b/backport/backport-include/linux/netdevice.h
index 411757d2..ed691961 100644
--- a/backport/backport-include/linux/netdevice.h
+++ b/backport/backport-include/linux/netdevice.h
@@ -401,6 +401,10 @@ static inline bool netif_is_bridge_port(const struct net_device *dev)
 #endif
 
 #if LINUX_VERSION_IS_LESS(5,10,0)
+#define dev_fetch_sw_netstats LINUX_BACKPORT(dev_fetch_sw_netstats)
+void dev_fetch_sw_netstats(struct rtnl_link_stats64 *s,
+			   const struct pcpu_sw_netstats __percpu *netstats);
+
 #define netif_rx_any_context LINUX_BACKPORT(netif_rx_any_context)
 int netif_rx_any_context(struct sk_buff *skb);
 #endif /* < 5.10 */
diff --git a/backport/compat/backport-5.10.c b/backport/compat/backport-5.10.c
index a83907f4..141862da 100644
--- a/backport/compat/backport-5.10.c
+++ b/backport/compat/backport-5.10.c
@@ -4,6 +4,40 @@
 #include <linux/kernel.h>
 #include <linux/netdevice.h>
 
+/**
+ *	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);
+
 int netif_rx_any_context(struct sk_buff *skb)
 {
 	/*
-- 
2.20.1

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