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Commit 5eaa0bd8 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

loopback: use u64_stats_sync infrastructure 



Commit 6b10de38 (loopback: Implement 64bit stats on 32bit arches)
introduced 64bit stats in loopback driver, using a private seqcount and
private helpers.

David suggested to introduce a generic infrastructure, added in (net:
Introduce u64_stats_sync infrastructure)

This patch reimplements loopback 64bit stats using the u64_stats_sync
infrastructure.

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4b4194c4

drivers/net/loopback.c

+16 −46
Original line number Diff line number Diff line
@@ -58,53 +58,15 @@ 
#include <linux/tcp.h>

#include <linux/percpu.h>

#include <net/net_namespace.h>

#include <linux/u64_stats_sync.h>



struct pcpu_lstats {

	u64			packets;

	u64			bytes;

#if BITS_PER_LONG==32 && defined(CONFIG_SMP)

	seqcount_t seq;

#endif

	struct u64_stats_sync	syncp;

	unsigned long		drops;

};



#if BITS_PER_LONG==32 && defined(CONFIG_SMP)

static void inline lstats_update_begin(struct pcpu_lstats *lstats)

{

	write_seqcount_begin(&lstats->seq);

}

static void inline lstats_update_end(struct pcpu_lstats *lstats)

{

	write_seqcount_end(&lstats->seq);

}

static void inline lstats_fetch_and_add(u64 *packets, u64 *bytes, const struct pcpu_lstats *lstats)

{

	u64 tpackets, tbytes;

	unsigned int seq;



	do {

		seq = read_seqcount_begin(&lstats->seq);

		tpackets = lstats->packets;

		tbytes = lstats->bytes;

	} while (read_seqcount_retry(&lstats->seq, seq));



	*packets += tpackets;

	*bytes += tbytes;

}

#else

static void inline lstats_update_begin(struct pcpu_lstats *lstats)

{

}

static void inline lstats_update_end(struct pcpu_lstats *lstats)

{

}

static void inline lstats_fetch_and_add(u64 *packets, u64 *bytes, const struct pcpu_lstats *lstats)

{

	*packets += lstats->packets;

	*bytes += lstats->bytes;

}

#endif



/*

 * The higher levels take care of making this non-reentrant (it's

 * called with bh's disabled).
@@ -126,10 +88,10 @@ static netdev_tx_t loopback_xmit(struct sk_buff *skb, 


	len = skb->len;

	if (likely(netif_rx(skb) == NET_RX_SUCCESS)) {

		lstats_update_begin(lb_stats);

		u64_stats_update_begin(&lb_stats->syncp);

		lb_stats->bytes += len;

		lb_stats->packets++;

		lstats_update_end(lb_stats);

		u64_stats_update_end(&lb_stats->syncp);

	} else

		lb_stats->drops++;
@@ -148,10 +110,18 @@ static struct rtnl_link_stats64 *loopback_get_stats64(struct net_device *dev) 
	pcpu_lstats = (void __percpu __force *)dev->ml_priv;

	for_each_possible_cpu(i) {

		const struct pcpu_lstats *lb_stats;

		u64 tbytes, tpackets;

		unsigned int start;



		lb_stats = per_cpu_ptr(pcpu_lstats, i);

		lstats_fetch_and_add(&packets, &bytes, lb_stats);

		do {

			start = u64_stats_fetch_begin(&lb_stats->syncp);

			tbytes = lb_stats->bytes;

			tpackets = lb_stats->packets;

		} while (u64_stats_fetch_retry(&lb_stats->syncp, start));

		drops   += lb_stats->drops;

		bytes   += tbytes;

		packets += tpackets;

	}

	stats->rx_packets = packets;

	stats->tx_packets = packets;