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loopback: Implement 64bit stats on 32bit arches

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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: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-06-14 05:59:22 +00:00 committed by David S. Miller
parent c68f24cc35
commit 6b10de38f0
1 changed files with 51 additions and 10 deletions
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61
drivers/net/loopback.c
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@ -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,
};
/*