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mpls: Packet stats
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Having MPLS packet stats is useful for observing network operation and
for diagnosing network problems. In the absence of anything better,
RFC2863 and RFC3813 are used for guidance for which stats to expose
and the semantics of them. In particular rx_noroutes maps to in
unknown protos in RFC2863. The stats are exposed to userspace via
AF_MPLS attributes embedded in the IFLA_STATS_AF_SPEC attribute of
RTM_GETSTATS messages.

All the introduced fields are 64-bit, even error ones, to ensure no
overflow with long uptimes. Per-CPU counters are used to avoid
cache-line contention on the commonly used fields. The other fields
have also been made per-CPU for code to avoid performance problems in
error conditions on the assumption that on some platforms the cost of
atomic operations could be more expensive than sending the packet
(which is what would be done in the success case). If that's not the
case, we could instead not use per-CPU counters for these fields.

Only unicast and non-fragment are exposed at the moment, but other
counters can be exposed in the future either by adding to the end of
struct mpls_link_stats or by additional netlink attributes in the
AF_MPLS IFLA_STATS_AF_SPEC nested attribute.

Signed-off-by: Robert Shearman <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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@rshearman @davem330
rshearman authored and davem330 committed Jan 17, 2017
1 parent aefb4d4 commit 27d6910
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Showing 4 changed files with 252 additions and 28 deletions.
30 changes: 30 additions & 0 deletions include/uapi/linux/mpls.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -43,4 +43,34 @@ struct mpls_label {

#define MPLS_LABEL_FIRST_UNRESERVED 16 /* RFC3032 */

/* These are embedded into IFLA_STATS_AF_SPEC:
* [IFLA_STATS_AF_SPEC]
* -> [AF_MPLS]
* -> [MPLS_STATS_xxx]
*
* Attributes:
* [MPLS_STATS_LINK] = {
* struct mpls_link_stats
* }
*/
enum {
MPLS_STATS_UNSPEC, /* also used as 64bit pad attribute */
MPLS_STATS_LINK,
__MPLS_STATS_MAX,
};

#define MPLS_STATS_MAX (__MPLS_STATS_MAX - 1)

struct mpls_link_stats {
__u64 rx_packets; /* total packets received */
__u64 tx_packets; /* total packets transmitted */
__u64 rx_bytes; /* total bytes received */
__u64 tx_bytes; /* total bytes transmitted */
__u64 rx_errors; /* bad packets received */
__u64 tx_errors; /* packet transmit problems */
__u64 rx_dropped; /* packet dropped on receive */
__u64 tx_dropped; /* packet dropped on transmit */
__u64 rx_noroute; /* no route for packet dest */
};

#endif /* _UAPI_MPLS_H */
181 changes: 158 additions & 23 deletions net/mpls/af_mpls.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@
#include <linux/ipv6.h>
#include <linux/mpls.h>
#include <linux/vmalloc.h>
#include <linux/percpu.h>
#include <net/ip.h>
#include <net/dst.h>
#include <net/sock.h>
Expand All @@ -17,8 +18,8 @@
#include <net/netns/generic.h>
#if IS_ENABLED(CONFIG_IPV6)
#include <net/ipv6.h>
#include <net/addrconf.h>
#endif
#include <net/addrconf.h>
#include <net/nexthop.h>
#include "internal.h"

Expand Down Expand Up @@ -48,11 +49,6 @@ static struct mpls_route *mpls_route_input_rcu(struct net *net, unsigned index)
return rt;
}

static inline struct mpls_dev *mpls_dev_get(const struct net_device *dev)
{
return rcu_dereference_rtnl(dev->mpls_ptr);
}

bool mpls_output_possible(const struct net_device *dev)
{
return dev && (dev->flags & IFF_UP) && netif_carrier_ok(dev);
Expand Down Expand Up @@ -98,6 +94,31 @@ bool mpls_pkt_too_big(const struct sk_buff *skb, unsigned int mtu)
}
EXPORT_SYMBOL_GPL(mpls_pkt_too_big);

void mpls_stats_inc_outucastpkts(struct net_device *dev,
const struct sk_buff *skb)
{
struct mpls_dev *mdev;

if (skb->protocol == htons(ETH_P_MPLS_UC)) {
mdev = mpls_dev_get(dev);
if (mdev)
MPLS_INC_STATS_LEN(mdev, skb->len,
tx_packets,
tx_bytes);
} else if (skb->protocol == htons(ETH_P_IP)) {
IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
#if IS_ENABLED(CONFIG_IPV6)
} else if (skb->protocol == htons(ETH_P_IPV6)) {
struct inet6_dev *in6dev = __in6_dev_get(dev);

if (in6dev)
IP6_UPD_PO_STATS(dev_net(dev), in6dev,
IPSTATS_MIB_OUT, skb->len);
#endif
}
}
EXPORT_SYMBOL_GPL(mpls_stats_inc_outucastpkts);

static u32 mpls_multipath_hash(struct mpls_route *rt,
struct sk_buff *skb, bool bos)
{
Expand Down Expand Up @@ -253,6 +274,7 @@ static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
struct mpls_nh *nh;
struct mpls_entry_decoded dec;
struct net_device *out_dev;
struct mpls_dev *out_mdev;
struct mpls_dev *mdev;
unsigned int hh_len;
unsigned int new_header_size;
Expand All @@ -262,17 +284,25 @@ static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
/* Careful this entire function runs inside of an rcu critical section */

mdev = mpls_dev_get(dev);
if (!mdev || !mdev->input_enabled)
if (!mdev)
goto drop;

if (skb->pkt_type != PACKET_HOST)
MPLS_INC_STATS_LEN(mdev, skb->len, rx_packets,
rx_bytes);

if (!mdev->input_enabled) {
MPLS_INC_STATS(mdev, rx_dropped);
goto drop;
}

if (skb->pkt_type != PACKET_HOST)
goto err;

if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
goto drop;
goto err;

if (!pskb_may_pull(skb, sizeof(*hdr)))
goto drop;
goto err;

/* Read and decode the label */
hdr = mpls_hdr(skb);
Expand All @@ -285,49 +315,51 @@ static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
skb_orphan(skb);

rt = mpls_route_input_rcu(net, dec.label);
if (!rt)
if (!rt) {
MPLS_INC_STATS(mdev, rx_noroute);
goto drop;
}

nh = mpls_select_multipath(rt, skb, dec.bos);
if (!nh)
goto drop;

/* Find the output device */
out_dev = rcu_dereference(nh->nh_dev);
if (!mpls_output_possible(out_dev))
goto drop;
goto err;

if (skb_warn_if_lro(skb))
goto drop;
goto err;

skb_forward_csum(skb);

/* Verify ttl is valid */
if (dec.ttl <= 1)
goto drop;
goto err;
dec.ttl -= 1;

/* Find the output device */
out_dev = rcu_dereference(nh->nh_dev);
if (!mpls_output_possible(out_dev))
goto tx_err;

/* Verify the destination can hold the packet */
new_header_size = mpls_nh_header_size(nh);
mtu = mpls_dev_mtu(out_dev);
if (mpls_pkt_too_big(skb, mtu - new_header_size))
goto drop;
goto tx_err;

hh_len = LL_RESERVED_SPACE(out_dev);
if (!out_dev->header_ops)
hh_len = 0;

/* Ensure there is enough space for the headers in the skb */
if (skb_cow(skb, hh_len + new_header_size))
goto drop;
goto tx_err;

skb->dev = out_dev;
skb->protocol = htons(ETH_P_MPLS_UC);

if (unlikely(!new_header_size && dec.bos)) {
/* Penultimate hop popping */
if (!mpls_egress(rt, skb, dec))
goto drop;
goto err;
} else {
bool bos;
int i;
Expand All @@ -343,6 +375,8 @@ static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
}
}

mpls_stats_inc_outucastpkts(out_dev, skb);

/* If via wasn't specified then send out using device address */
if (nh->nh_via_table == MPLS_NEIGH_TABLE_UNSPEC)
err = neigh_xmit(NEIGH_LINK_TABLE, out_dev,
Expand All @@ -355,6 +389,13 @@ static int mpls_forward(struct sk_buff *skb, struct net_device *dev,
__func__, err);
return 0;

tx_err:
out_mdev = out_dev ? mpls_dev_get(out_dev) : NULL;
if (out_mdev)
MPLS_INC_STATS(out_mdev, tx_errors);
goto drop;
err:
MPLS_INC_STATS(mdev, rx_errors);
drop:
kfree_skb(skb);
return NET_RX_DROP;
Expand Down Expand Up @@ -853,6 +894,70 @@ static int mpls_route_del(struct mpls_route_config *cfg)
return err;
}

static void mpls_get_stats(struct mpls_dev *mdev,
struct mpls_link_stats *stats)
{
struct mpls_pcpu_stats *p;
int i;

memset(stats, 0, sizeof(*stats));

for_each_possible_cpu(i) {
struct mpls_link_stats local;
unsigned int start;

p = per_cpu_ptr(mdev->stats, i);
do {
start = u64_stats_fetch_begin(&p->syncp);
local = p->stats;
} while (u64_stats_fetch_retry(&p->syncp, start));

stats->rx_packets += local.rx_packets;
stats->rx_bytes += local.rx_bytes;
stats->tx_packets += local.tx_packets;
stats->tx_bytes += local.tx_bytes;
stats->rx_errors += local.rx_errors;
stats->tx_errors += local.tx_errors;
stats->rx_dropped += local.rx_dropped;
stats->tx_dropped += local.tx_dropped;
stats->rx_noroute += local.rx_noroute;
}
}

static int mpls_fill_stats_af(struct sk_buff *skb,
const struct net_device *dev)
{
struct mpls_link_stats *stats;
struct mpls_dev *mdev;
struct nlattr *nla;

mdev = mpls_dev_get(dev);
if (!mdev)
return -ENODATA;

nla = nla_reserve_64bit(skb, MPLS_STATS_LINK,
sizeof(struct mpls_link_stats),
MPLS_STATS_UNSPEC);
if (!nla)
return -EMSGSIZE;

stats = nla_data(nla);
mpls_get_stats(mdev, stats);

return 0;
}

static size_t mpls_get_stats_af_size(const struct net_device *dev)
{
struct mpls_dev *mdev;

mdev = mpls_dev_get(dev);
if (!mdev)
return 0;

return nla_total_size_64bit(sizeof(struct mpls_link_stats));
}

#define MPLS_PERDEV_SYSCTL_OFFSET(field) \
(&((struct mpls_dev *)0)->field)

Expand Down Expand Up @@ -911,13 +1016,25 @@ static struct mpls_dev *mpls_add_dev(struct net_device *dev)
{
struct mpls_dev *mdev;
int err = -ENOMEM;
int i;

ASSERT_RTNL();

mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
if (!mdev)
return ERR_PTR(err);

mdev->stats = alloc_percpu(struct mpls_pcpu_stats);
if (!mdev->stats)
goto free;

for_each_possible_cpu(i) {
struct mpls_pcpu_stats *mpls_stats;

mpls_stats = per_cpu_ptr(mdev->stats, i);
u64_stats_init(&mpls_stats->syncp);
}

err = mpls_dev_sysctl_register(dev, mdev);
if (err)
goto free;
Expand All @@ -927,10 +1044,19 @@ static struct mpls_dev *mpls_add_dev(struct net_device *dev)
return mdev;

free:
free_percpu(mdev->stats);
kfree(mdev);
return ERR_PTR(err);
}

static void mpls_dev_destroy_rcu(struct rcu_head *head)
{
struct mpls_dev *mdev = container_of(head, struct mpls_dev, rcu);

free_percpu(mdev->stats);
kfree(mdev);
}

static void mpls_ifdown(struct net_device *dev, int event)
{
struct mpls_route __rcu **platform_label;
Expand Down Expand Up @@ -1045,7 +1171,7 @@ static int mpls_dev_notify(struct notifier_block *this, unsigned long event,
if (mdev) {
mpls_dev_sysctl_unregister(mdev);
RCU_INIT_POINTER(dev->mpls_ptr, NULL);
kfree_rcu(mdev, rcu);
call_rcu(&mdev->rcu, mpls_dev_destroy_rcu);
}
break;
case NETDEV_CHANGENAME:
Expand Down Expand Up @@ -1706,6 +1832,12 @@ static struct pernet_operations mpls_net_ops = {
.exit = mpls_net_exit,
};

static struct rtnl_af_ops mpls_af_ops __read_mostly = {
.family = AF_MPLS,
.fill_stats_af = mpls_fill_stats_af,
.get_stats_af_size = mpls_get_stats_af_size,
};

static int __init mpls_init(void)
{
int err;
Expand All @@ -1722,6 +1854,8 @@ static int __init mpls_init(void)

dev_add_pack(&mpls_packet_type);

rtnl_af_register(&mpls_af_ops);

rtnl_register(PF_MPLS, RTM_NEWROUTE, mpls_rtm_newroute, NULL, NULL);
rtnl_register(PF_MPLS, RTM_DELROUTE, mpls_rtm_delroute, NULL, NULL);
rtnl_register(PF_MPLS, RTM_GETROUTE, NULL, mpls_dump_routes, NULL);
Expand All @@ -1738,6 +1872,7 @@ module_init(mpls_init);
static void __exit mpls_exit(void)
{
rtnl_unregister_all(PF_MPLS);
rtnl_af_unregister(&mpls_af_ops);
dev_remove_pack(&mpls_packet_type);
unregister_netdevice_notifier(&mpls_dev_notifier);
unregister_pernet_subsys(&mpls_net_ops);
Expand Down
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