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tun: switch to net core provided statistics counters
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Switch tun to the standard statistics pattern:
- use netdev->stats for the less frequently accessed counters
- use netdev->tstats for the frequently accessed per-cpu counters

v3:
- add atomic_long_t member rx_frame_errors for making counter updates
  atomic

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Heiner Kallweit authored and Jakub Kicinski committed Nov 10, 2020
1 parent 6a90062 commit 497a575
Showing 1 changed file with 34 additions and 87 deletions.
121 changes: 34 additions & 87 deletions drivers/net/tun.c
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Original file line number Diff line number Diff line change
Expand Up @@ -107,17 +107,6 @@ struct tap_filter {

#define TUN_FLOW_EXPIRE (3 * HZ)

struct tun_pcpu_stats {
u64_stats_t rx_packets;
u64_stats_t rx_bytes;
u64_stats_t tx_packets;
u64_stats_t 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
Expand Down Expand Up @@ -207,7 +196,7 @@ struct tun_struct {
void *security;
u32 flow_count;
u32 rx_batched;
struct tun_pcpu_stats __percpu *pcpu_stats;
atomic_long_t rx_frame_errors;
struct bpf_prog __rcu *xdp_prog;
struct tun_prog __rcu *steering_prog;
struct tun_prog __rcu *filter_prog;
Expand Down Expand Up @@ -1066,7 +1055,7 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev)
return NETDEV_TX_OK;

drop:
this_cpu_inc(tun->pcpu_stats->tx_dropped);
atomic_long_inc(&dev->tx_dropped);
skb_tx_error(skb);
kfree_skb(skb);
rcu_read_unlock();
Expand Down Expand Up @@ -1103,37 +1092,12 @@ static void tun_set_headroom(struct net_device *dev, int new_hr)
static void
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 = u64_stats_read(&p->rx_packets);
rxbytes = u64_stats_read(&p->rx_bytes);
txpackets = u64_stats_read(&p->tx_packets);
txbytes = u64_stats_read(&p->tx_bytes);
} while (u64_stats_fetch_retry(&p->syncp, start));
dev_get_tstats64(dev, stats);

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;
stats->rx_frame_errors +=
(unsigned long)atomic_long_read(&tun->rx_frame_errors);
}

static int tun_xdp_set(struct net_device *dev, struct bpf_prog *prog,
Expand Down Expand Up @@ -1247,7 +1211,7 @@ static int tun_xdp_xmit(struct net_device *dev, int n,
void *frame = tun_xdp_to_ptr(xdp);

if (__ptr_ring_produce(&tfile->tx_ring, frame)) {
this_cpu_inc(tun->pcpu_stats->tx_dropped);
atomic_long_inc(&dev->tx_dropped);
xdp_return_frame_rx_napi(xdp);
drops++;
}
Expand Down Expand Up @@ -1283,7 +1247,7 @@ static const struct net_device_ops tap_netdev_ops = {
.ndo_select_queue = tun_select_queue,
.ndo_features_check = passthru_features_check,
.ndo_set_rx_headroom = tun_set_headroom,
.ndo_get_stats64 = tun_net_get_stats64,
.ndo_get_stats64 = dev_get_tstats64,
.ndo_bpf = tun_xdp,
.ndo_xdp_xmit = tun_xdp_xmit,
.ndo_change_carrier = tun_net_change_carrier,
Expand Down Expand Up @@ -1577,7 +1541,7 @@ static int tun_xdp_act(struct tun_struct *tun, struct bpf_prog *xdp_prog,
trace_xdp_exception(tun->dev, xdp_prog, act);
fallthrough;
case XDP_DROP:
this_cpu_inc(tun->pcpu_stats->rx_dropped);
atomic_long_inc(&tun->dev->rx_dropped);
break;
}

Expand Down Expand Up @@ -1683,7 +1647,6 @@ 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;
Expand Down Expand Up @@ -1752,7 +1715,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
*/
skb = tun_build_skb(tun, tfile, from, &gso, len, &skb_xdp);
if (IS_ERR(skb)) {
this_cpu_inc(tun->pcpu_stats->rx_dropped);
atomic_long_inc(&tun->dev->rx_dropped);
return PTR_ERR(skb);
}
if (!skb)
Expand Down Expand Up @@ -1781,7 +1744,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,

if (IS_ERR(skb)) {
if (PTR_ERR(skb) != -EAGAIN)
this_cpu_inc(tun->pcpu_stats->rx_dropped);
atomic_long_inc(&tun->dev->rx_dropped);
if (frags)
mutex_unlock(&tfile->napi_mutex);
return PTR_ERR(skb);
Expand All @@ -1795,7 +1758,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
if (err) {
err = -EFAULT;
drop:
this_cpu_inc(tun->pcpu_stats->rx_dropped);
atomic_long_inc(&tun->dev->rx_dropped);
kfree_skb(skb);
if (frags) {
tfile->napi.skb = NULL;
Expand All @@ -1807,7 +1770,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
}

if (virtio_net_hdr_to_skb(skb, &gso, tun_is_little_endian(tun))) {
this_cpu_inc(tun->pcpu_stats->rx_frame_errors);
atomic_long_inc(&tun->rx_frame_errors);
kfree_skb(skb);
if (frags) {
tfile->napi.skb = NULL;
Expand All @@ -1830,7 +1793,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
pi.proto = htons(ETH_P_IPV6);
break;
default:
this_cpu_inc(tun->pcpu_stats->rx_dropped);
atomic_long_inc(&tun->dev->rx_dropped);
kfree_skb(skb);
return -EINVAL;
}
Expand Down Expand Up @@ -1910,7 +1873,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
skb_headlen(skb));

if (unlikely(headlen > skb_headlen(skb))) {
this_cpu_inc(tun->pcpu_stats->rx_dropped);
atomic_long_inc(&tun->dev->rx_dropped);
napi_free_frags(&tfile->napi);
rcu_read_unlock();
mutex_unlock(&tfile->napi_mutex);
Expand Down Expand Up @@ -1942,12 +1905,9 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
}
rcu_read_unlock();

stats = get_cpu_ptr(tun->pcpu_stats);
u64_stats_update_begin(&stats->syncp);
u64_stats_inc(&stats->rx_packets);
u64_stats_add(&stats->rx_bytes, len);
u64_stats_update_end(&stats->syncp);
put_cpu_ptr(stats);
preempt_disable();
dev_sw_netstats_rx_add(tun->dev, len);
preempt_enable();

if (rxhash)
tun_flow_update(tun, rxhash, tfile);
Expand Down Expand Up @@ -1979,7 +1939,6 @@ static ssize_t tun_put_user_xdp(struct tun_struct *tun,
{
int vnet_hdr_sz = 0;
size_t size = xdp_frame->len;
struct tun_pcpu_stats *stats;
size_t ret;

if (tun->flags & IFF_VNET_HDR) {
Expand All @@ -1996,12 +1955,9 @@ static ssize_t tun_put_user_xdp(struct tun_struct *tun,

ret = copy_to_iter(xdp_frame->data, size, iter) + vnet_hdr_sz;

stats = get_cpu_ptr(tun->pcpu_stats);
u64_stats_update_begin(&stats->syncp);
u64_stats_inc(&stats->tx_packets);
u64_stats_add(&stats->tx_bytes, ret);
u64_stats_update_end(&stats->syncp);
put_cpu_ptr(tun->pcpu_stats);
preempt_disable();
dev_sw_netstats_tx_add(tun->dev, 1, ret);
preempt_enable();

return ret;
}
Expand All @@ -2013,7 +1969,6 @@ 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;
Expand Down Expand Up @@ -2091,12 +2046,9 @@ static ssize_t tun_put_user(struct tun_struct *tun,

done:
/* caller is in process context, */
stats = get_cpu_ptr(tun->pcpu_stats);
u64_stats_update_begin(&stats->syncp);
u64_stats_inc(&stats->tx_packets);
u64_stats_add(&stats->tx_bytes, skb->len + vlan_hlen);
u64_stats_update_end(&stats->syncp);
put_cpu_ptr(tun->pcpu_stats);
preempt_disable();
dev_sw_netstats_tx_add(tun->dev, 1, skb->len + vlan_hlen);
preempt_enable();

return total;
}
Expand Down Expand Up @@ -2235,11 +2187,11 @@ static void tun_free_netdev(struct net_device *dev)

BUG_ON(!(list_empty(&tun->disabled)));

free_percpu(tun->pcpu_stats);
/* We clear pcpu_stats so that tun_set_iff() can tell if
free_percpu(dev->tstats);
/* We clear tstats so that tun_set_iff() can tell if
* tun_free_netdev() has been called from register_netdevice().
*/
tun->pcpu_stats = NULL;
dev->tstats = NULL;

tun_flow_uninit(tun);
security_tun_dev_free_security(tun->security);
Expand Down Expand Up @@ -2370,7 +2322,6 @@ static int tun_xdp_one(struct tun_struct *tun,
unsigned int datasize = xdp->data_end - xdp->data;
struct tun_xdp_hdr *hdr = xdp->data_hard_start;
struct virtio_net_hdr *gso = &hdr->gso;
struct tun_pcpu_stats *stats;
struct bpf_prog *xdp_prog;
struct sk_buff *skb = NULL;
u32 rxhash = 0, act;
Expand Down Expand Up @@ -2428,7 +2379,7 @@ static int tun_xdp_one(struct tun_struct *tun,
skb_put(skb, xdp->data_end - xdp->data);

if (virtio_net_hdr_to_skb(skb, gso, tun_is_little_endian(tun))) {
this_cpu_inc(tun->pcpu_stats->rx_frame_errors);
atomic_long_inc(&tun->rx_frame_errors);
kfree_skb(skb);
err = -EINVAL;
goto out;
Expand All @@ -2451,14 +2402,10 @@ static int tun_xdp_one(struct tun_struct *tun,

netif_receive_skb(skb);

/* No need for get_cpu_ptr() here since this function is
/* No need to disable preemption here since this function is
* always called with bh disabled
*/
stats = this_cpu_ptr(tun->pcpu_stats);
u64_stats_update_begin(&stats->syncp);
u64_stats_inc(&stats->rx_packets);
u64_stats_add(&stats->rx_bytes, datasize);
u64_stats_update_end(&stats->syncp);
dev_sw_netstats_rx_add(tun->dev, datasize);

if (rxhash)
tun_flow_update(tun, rxhash, tfile);
Expand Down Expand Up @@ -2751,8 +2698,8 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
tun->rx_batched = 0;
RCU_INIT_POINTER(tun->steering_prog, NULL);

tun->pcpu_stats = netdev_alloc_pcpu_stats(struct tun_pcpu_stats);
if (!tun->pcpu_stats) {
dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
if (!dev->tstats) {
err = -ENOMEM;
goto err_free_dev;
}
Expand Down Expand Up @@ -2807,16 +2754,16 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
tun_detach_all(dev);
/* We are here because register_netdevice() has failed.
* If register_netdevice() already called tun_free_netdev()
* while dealing with the error, tun->pcpu_stats has been cleared.
* while dealing with the error, dev->stats has been cleared.
*/
if (!tun->pcpu_stats)
if (!dev->tstats)
goto err_free_dev;

err_free_flow:
tun_flow_uninit(tun);
security_tun_dev_free_security(tun->security);
err_free_stat:
free_percpu(tun->pcpu_stats);
free_percpu(dev->tstats);
err_free_dev:
free_netdev(dev);
return err;
Expand Down

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