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Commit 6b10de38 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

loopback: Implement 64bit stats on 32bit arches 



Uses a seqcount_t to synchronize stat producer and consumer, for packets
and bytes counter, now u64 types.

(dropped counter being rarely used, stay a native "unsigned long" type)

No noticeable performance impact on x86, as it only adds two increments
per frame. It might be more expensive on arches where smp_wmb() is not
free.

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c68f24cc

drivers/net/loopback.c

+51 −10
Original line number Diff line number Diff line
@@ -60,11 +60,51 @@ 
#include <net/net_namespace.h>



struct pcpu_lstats {

	unsigned long packets;

	unsigned long bytes;

	u64 packets;

	u64 bytes;

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

	seqcount_t seq;

#endif

	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).
@@ -86,21 +126,23 @@ 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);

		lb_stats->bytes += len;

		lb_stats->packets++;

		lstats_update_end(lb_stats);

	} else

		lb_stats->drops++;



	return NETDEV_TX_OK;

}



static struct net_device_stats *loopback_get_stats(struct net_device *dev)

static struct rtnl_link_stats64 *loopback_get_stats64(struct net_device *dev)

{

	const struct pcpu_lstats __percpu *pcpu_lstats;

	struct net_device_stats *stats = &dev->stats;

	unsigned long bytes = 0;

	unsigned long packets = 0;

	unsigned long drops = 0;

	struct rtnl_link_stats64 *stats = &dev->stats64;

	u64 bytes = 0;

	u64 packets = 0;

	u64 drops = 0;

	int i;



	pcpu_lstats = (void __percpu __force *)dev->ml_priv;
@@ -108,8 +150,7 @@ static struct net_device_stats *loopback_get_stats(struct net_device *dev) 
		const struct pcpu_lstats *lb_stats;



		lb_stats = per_cpu_ptr(pcpu_lstats, i);

		bytes   += lb_stats->bytes;

		packets += lb_stats->packets;

		lstats_fetch_and_add(&packets, &bytes, lb_stats);

		drops   += lb_stats->drops;

	}

	stats->rx_packets = packets;
@@ -158,7 +199,7 @@ static void loopback_dev_free(struct net_device *dev) 
static const struct net_device_ops loopback_ops = {

	.ndo_init      = loopback_dev_init,

	.ndo_start_xmit= loopback_xmit,

	.ndo_get_stats = loopback_get_stats,

	.ndo_get_stats64 = loopback_get_stats64,

};



/*