vlan: Precise RX stats accounting
With multi queue devices, its possible that several cpus call
vlan RX routines simultaneously for the same vlan device.
We update RX stats counter without any locking, so we can
get slightly wrong counters.
One possible fix is to use percpu counters, to get precise
accounting and also get guarantee of no cache line ping pongs
between cpus.
Note: this adds 16 bytes (32 bytes on 64bit arches) of percpu
data per vlan device.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/8021q/vlan.h b/net/8021q/vlan.h
index 68f9290..5685296 100644
--- a/net/8021q/vlan.h
+++ b/net/8021q/vlan.h
@@ -16,6 +16,21 @@
struct vlan_priority_tci_mapping *next;
};
+
+/**
+ * struct vlan_rx_stats - VLAN percpu rx stats
+ * @rx_packets: number of received packets
+ * @rx_bytes: number of received bytes
+ * @multicast: number of received multicast packets
+ * @rx_errors: number of errors
+ */
+struct vlan_rx_stats {
+ unsigned long rx_packets;
+ unsigned long rx_bytes;
+ unsigned long multicast;
+ unsigned long rx_errors;
+};
+
/**
* struct vlan_dev_info - VLAN private device data
* @nr_ingress_mappings: number of ingress priority mappings
@@ -29,6 +44,7 @@
* @dent: proc dir entry
* @cnt_inc_headroom_on_tx: statistic - number of skb expansions on TX
* @cnt_encap_on_xmit: statistic - number of skb encapsulations on TX
+ * @vlan_rx_stats: ptr to percpu rx stats
*/
struct vlan_dev_info {
unsigned int nr_ingress_mappings;
@@ -45,6 +61,7 @@
struct proc_dir_entry *dent;
unsigned long cnt_inc_headroom_on_tx;
unsigned long cnt_encap_on_xmit;
+ struct vlan_rx_stats *vlan_rx_stats;
};
static inline struct vlan_dev_info *vlan_dev_info(const struct net_device *dev)
diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
index 971d375..e75a2f3 100644
--- a/net/8021q/vlan_core.c
+++ b/net/8021q/vlan_core.c
@@ -31,7 +31,7 @@
int vlan_hwaccel_do_receive(struct sk_buff *skb)
{
struct net_device *dev = skb->dev;
- struct net_device_stats *stats;
+ struct vlan_rx_stats *rx_stats;
skb->dev = vlan_dev_info(dev)->real_dev;
netif_nit_deliver(skb);
@@ -40,15 +40,17 @@
skb->priority = vlan_get_ingress_priority(dev, skb->vlan_tci);
skb->vlan_tci = 0;
- stats = &dev->stats;
- stats->rx_packets++;
- stats->rx_bytes += skb->len;
+ rx_stats = per_cpu_ptr(vlan_dev_info(dev)->vlan_rx_stats,
+ smp_processor_id());
+
+ rx_stats->rx_packets++;
+ rx_stats->rx_bytes += skb->len;
switch (skb->pkt_type) {
case PACKET_BROADCAST:
break;
case PACKET_MULTICAST:
- stats->multicast++;
+ rx_stats->multicast++;
break;
case PACKET_OTHERHOST:
/* Our lower layer thinks this is not local, let's make sure.
diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index 9159659..de0dc6b 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -140,7 +140,7 @@
struct packet_type *ptype, struct net_device *orig_dev)
{
struct vlan_hdr *vhdr;
- struct net_device_stats *stats;
+ struct vlan_rx_stats *rx_stats;
u16 vlan_id;
u16 vlan_tci;
@@ -163,9 +163,10 @@
goto err_unlock;
}
- stats = &skb->dev->stats;
- stats->rx_packets++;
- stats->rx_bytes += skb->len;
+ rx_stats = per_cpu_ptr(vlan_dev_info(dev)->vlan_rx_stats,
+ smp_processor_id());
+ rx_stats->rx_packets++;
+ rx_stats->rx_bytes += skb->len;
skb_pull_rcsum(skb, VLAN_HLEN);
@@ -180,7 +181,7 @@
break;
case PACKET_MULTICAST:
- stats->multicast++;
+ rx_stats->multicast++;
break;
case PACKET_OTHERHOST:
@@ -200,7 +201,7 @@
skb = vlan_check_reorder_header(skb);
if (!skb) {
- stats->rx_errors++;
+ rx_stats->rx_errors++;
goto err_unlock;
}
@@ -731,6 +732,11 @@
subclass = 1;
vlan_dev_set_lockdep_class(dev, subclass);
+
+ vlan_dev_info(dev)->vlan_rx_stats = alloc_percpu(struct vlan_rx_stats);
+ if (!vlan_dev_info(dev)->vlan_rx_stats)
+ return -ENOMEM;
+
return 0;
}
@@ -740,6 +746,8 @@
struct vlan_dev_info *vlan = vlan_dev_info(dev);
int i;
+ free_percpu(vlan->vlan_rx_stats);
+ vlan->vlan_rx_stats = NULL;
for (i = 0; i < ARRAY_SIZE(vlan->egress_priority_map); i++) {
while ((pm = vlan->egress_priority_map[i]) != NULL) {
vlan->egress_priority_map[i] = pm->next;
@@ -775,6 +783,31 @@
return dev_ethtool_get_flags(vlan->real_dev);
}
+static struct net_device_stats *vlan_dev_get_stats(struct net_device *dev)
+{
+ struct net_device_stats *stats = &dev->stats;
+
+ dev_txq_stats_fold(dev, stats);
+
+ if (vlan_dev_info(dev)->vlan_rx_stats) {
+ struct vlan_rx_stats *p, rx = {0};
+ int i;
+
+ for_each_possible_cpu(i) {
+ p = per_cpu_ptr(vlan_dev_info(dev)->vlan_rx_stats, i);
+ rx.rx_packets += p->rx_packets;
+ rx.rx_bytes += p->rx_bytes;
+ rx.rx_errors += p->rx_errors;
+ rx.multicast += p->multicast;
+ }
+ stats->rx_packets = rx.rx_packets;
+ stats->rx_bytes = rx.rx_bytes;
+ stats->rx_errors = rx.rx_errors;
+ stats->multicast = rx.multicast;
+ }
+ return stats;
+}
+
static const struct ethtool_ops vlan_ethtool_ops = {
.get_settings = vlan_ethtool_get_settings,
.get_drvinfo = vlan_ethtool_get_drvinfo,
@@ -797,6 +830,7 @@
.ndo_change_rx_flags = vlan_dev_change_rx_flags,
.ndo_do_ioctl = vlan_dev_ioctl,
.ndo_neigh_setup = vlan_dev_neigh_setup,
+ .ndo_get_stats = vlan_dev_get_stats,
#if defined(CONFIG_FCOE) || defined(CONFIG_FCOE_MODULE)
.ndo_fcoe_ddp_setup = vlan_dev_fcoe_ddp_setup,
.ndo_fcoe_ddp_done = vlan_dev_fcoe_ddp_done,
@@ -820,6 +854,7 @@
.ndo_change_rx_flags = vlan_dev_change_rx_flags,
.ndo_do_ioctl = vlan_dev_ioctl,
.ndo_neigh_setup = vlan_dev_neigh_setup,
+ .ndo_get_stats = vlan_dev_get_stats,
#if defined(CONFIG_FCOE) || defined(CONFIG_FCOE_MODULE)
.ndo_fcoe_ddp_setup = vlan_dev_fcoe_ddp_setup,
.ndo_fcoe_ddp_done = vlan_dev_fcoe_ddp_done,