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Message-Id: <597a2e5c2f664d48d3e4aac2f7d43e61940d4037.1460537477.git.pabeni@redhat.com>
Date: Wed, 13 Apr 2016 10:52:20 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
"Michael S. Tsirkin" <mst@...hat.com>,
Hannes Frederic Sowa <hannes@...essinduktion.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Greg Kurz <gkurz@...ux.vnet.ibm.com>,
Jason Wang <jasowang@...hat.com>
Subject: [PATCH net-next] tun: use per cpu variables for stats accounting
Currently the tun device accounting uses dev->stats without applying any
kind of protection, regardless that accounting happens in preemptible
process context.
This patch move the tun stats to a per cpu data structure, and protect
the updates with u64_stats_update_begin()/u64_stats_update_end() or
this_cpu_inc according to the stat type. The per cpu stats are
aggregated by the newly added ndo_get_stats64 ops.
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
---
drivers/net/tun.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 83 insertions(+), 12 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index a746616..faf9297 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -131,6 +131,17 @@ struct tap_filter {
#define TUN_FLOW_EXPIRE (3 * HZ)
+struct tun_pcpu_stats {
+ u64 rx_packets;
+ u64 rx_bytes;
+ u64 tx_packets;
+ u64 tx_bytes;
+ struct u64_stats_sync syncp;
+ u32 rx_dropped;
+ u32 tx_dropped;
+ u32 rx_frame_errors;
+};
+
/* A tun_file connects an open character device to a tuntap netdevice. It
* also contains all socket related structures (except sock_fprog and tap_filter)
* to serve as one transmit queue for tuntap device. The sock_fprog and
@@ -205,6 +216,7 @@ struct tun_struct {
struct list_head disabled;
void *security;
u32 flow_count;
+ struct tun_pcpu_stats __percpu *pcpu_stats;
};
#ifdef CONFIG_TUN_VNET_CROSS_LE
@@ -886,7 +898,7 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
return NETDEV_TX_OK;
drop:
- dev->stats.tx_dropped++;
+ this_cpu_inc(tun->pcpu_stats->tx_dropped);
skb_tx_error(skb);
kfree_skb(skb);
rcu_read_unlock();
@@ -949,6 +961,43 @@ static void tun_set_headroom(struct net_device *dev, int new_hr)
tun->align = new_hr;
}
+static struct rtnl_link_stats64 *
+tun_net_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
+{
+ u32 rx_dropped = 0, tx_dropped = 0, rx_frame_errors = 0;
+ struct tun_struct *tun = netdev_priv(dev);
+ struct tun_pcpu_stats *p;
+ int i;
+
+ for_each_possible_cpu(i) {
+ u64 rxpackets, rxbytes, txpackets, txbytes;
+ unsigned int start;
+
+ p = per_cpu_ptr(tun->pcpu_stats, i);
+ do {
+ start = u64_stats_fetch_begin(&p->syncp);
+ rxpackets = p->rx_packets;
+ rxbytes = p->rx_bytes;
+ txpackets = p->tx_packets;
+ txbytes = p->tx_bytes;
+ } while (u64_stats_fetch_retry(&p->syncp, start));
+
+ stats->rx_packets += rxpackets;
+ stats->rx_bytes += rxbytes;
+ stats->tx_packets += txpackets;
+ stats->tx_bytes += txbytes;
+
+ /* u32 counters */
+ rx_dropped += p->rx_dropped;
+ rx_frame_errors += p->rx_frame_errors;
+ tx_dropped += p->tx_dropped;
+ }
+ stats->rx_dropped = rx_dropped;
+ stats->rx_frame_errors = rx_frame_errors;
+ stats->tx_dropped = tx_dropped;
+ return stats;
+}
+
static const struct net_device_ops tun_netdev_ops = {
.ndo_uninit = tun_net_uninit,
.ndo_open = tun_net_open,
@@ -961,6 +1010,7 @@ static const struct net_device_ops tun_netdev_ops = {
.ndo_poll_controller = tun_poll_controller,
#endif
.ndo_set_rx_headroom = tun_set_headroom,
+ .ndo_get_stats64 = tun_net_get_stats64,
};
static const struct net_device_ops tap_netdev_ops = {
@@ -979,6 +1029,7 @@ static const struct net_device_ops tap_netdev_ops = {
#endif
.ndo_features_check = passthru_features_check,
.ndo_set_rx_headroom = tun_set_headroom,
+ .ndo_get_stats64 = tun_net_get_stats64,
};
static void tun_flow_init(struct tun_struct *tun)
@@ -1103,6 +1154,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
size_t total_len = iov_iter_count(from);
size_t len = total_len, align = tun->align, linear;
struct virtio_net_hdr gso = { 0 };
+ struct tun_pcpu_stats *stats;
int good_linear;
int copylen;
bool zerocopy = false;
@@ -1177,7 +1229,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
skb = tun_alloc_skb(tfile, align, copylen, linear, noblock);
if (IS_ERR(skb)) {
if (PTR_ERR(skb) != -EAGAIN)
- tun->dev->stats.rx_dropped++;
+ this_cpu_inc(tun->pcpu_stats->rx_dropped);
return PTR_ERR(skb);
}
@@ -1192,7 +1244,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
}
if (err) {
- tun->dev->stats.rx_dropped++;
+ this_cpu_inc(tun->pcpu_stats->rx_dropped);
kfree_skb(skb);
return -EFAULT;
}
@@ -1200,7 +1252,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
if (gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
if (!skb_partial_csum_set(skb, tun16_to_cpu(tun, gso.csum_start),
tun16_to_cpu(tun, gso.csum_offset))) {
- tun->dev->stats.rx_frame_errors++;
+ this_cpu_inc(tun->pcpu_stats->rx_frame_errors);
kfree_skb(skb);
return -EINVAL;
}
@@ -1217,7 +1269,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
pi.proto = htons(ETH_P_IPV6);
break;
default:
- tun->dev->stats.rx_dropped++;
+ this_cpu_inc(tun->pcpu_stats->rx_dropped);
kfree_skb(skb);
return -EINVAL;
}
@@ -1245,7 +1297,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
break;
default:
- tun->dev->stats.rx_frame_errors++;
+ this_cpu_inc(tun->pcpu_stats->rx_frame_errors);
kfree_skb(skb);
return -EINVAL;
}
@@ -1255,7 +1307,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
skb_shinfo(skb)->gso_size = tun16_to_cpu(tun, gso.gso_size);
if (skb_shinfo(skb)->gso_size == 0) {
- tun->dev->stats.rx_frame_errors++;
+ this_cpu_inc(tun->pcpu_stats->rx_frame_errors);
kfree_skb(skb);
return -EINVAL;
}
@@ -1278,8 +1330,12 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
rxhash = skb_get_hash(skb);
netif_rx_ni(skb);
- tun->dev->stats.rx_packets++;
- tun->dev->stats.rx_bytes += len;
+ stats = get_cpu_ptr(tun->pcpu_stats);
+ u64_stats_update_begin(&stats->syncp);
+ stats->rx_packets++;
+ stats->rx_bytes += len;
+ u64_stats_update_end(&stats->syncp);
+ put_cpu_ptr(stats);
tun_flow_update(tun, rxhash, tfile);
return total_len;
@@ -1308,6 +1364,7 @@ static ssize_t tun_put_user(struct tun_struct *tun,
struct iov_iter *iter)
{
struct tun_pi pi = { 0, skb->protocol };
+ struct tun_pcpu_stats *stats;
ssize_t total;
int vlan_offset = 0;
int vlan_hlen = 0;
@@ -1408,8 +1465,13 @@ static ssize_t tun_put_user(struct tun_struct *tun,
skb_copy_datagram_iter(skb, vlan_offset, iter, skb->len - vlan_offset);
done:
- tun->dev->stats.tx_packets++;
- tun->dev->stats.tx_bytes += skb->len + vlan_hlen;
+ /* caller is in process context, */
+ stats = get_cpu_ptr(tun->pcpu_stats);
+ u64_stats_update_begin(&stats->syncp);
+ stats->tx_packets++;
+ stats->tx_bytes += skb->len + vlan_hlen;
+ u64_stats_update_end(&stats->syncp);
+ put_cpu_ptr(tun->pcpu_stats);
return total;
}
@@ -1467,6 +1529,7 @@ static void tun_free_netdev(struct net_device *dev)
struct tun_struct *tun = netdev_priv(dev);
BUG_ON(!(list_empty(&tun->disabled)));
+ free_percpu(tun->pcpu_stats);
tun_flow_uninit(tun);
security_tun_dev_free_security(tun->security);
free_netdev(dev);
@@ -1715,11 +1778,17 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
tun->filter_attached = false;
tun->sndbuf = tfile->socket.sk->sk_sndbuf;
+ tun->pcpu_stats = netdev_alloc_pcpu_stats(struct tun_pcpu_stats);
+ if (!tun->pcpu_stats) {
+ err = -ENOMEM;
+ goto err_free_dev;
+ }
+
spin_lock_init(&tun->lock);
err = security_tun_dev_alloc_security(&tun->security);
if (err < 0)
- goto err_free_dev;
+ goto err_free_stat;
tun_net_init(dev);
tun_flow_init(tun);
@@ -1763,6 +1832,8 @@ err_detach:
err_free_flow:
tun_flow_uninit(tun);
security_tun_dev_free_security(tun->security);
+err_free_stat:
+ free_percpu(tun->pcpu_stats);
err_free_dev:
free_netdev(dev);
return err;
--
1.8.3.1
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