From: David Decotigny <de...@googlers.com>

Expose the number of times the link has been going UP or DOWN, and
update the "carrier_changes" counter to be the sum of these two events.
While at it, also update the sysfs-class-net documentation to cover:
carrier_changes (3.15), count_link_up (4.16) and count_link_down (4.16)

Signed-off-by: David Decotigny <de...@googlers.com>
[Florian:
* rebase
* add documentation
* merge carrier_changes with up/down counters]
Signed-off-by: Florian Fainelli <f.faine...@gmail.com>
---
 Documentation/ABI/testing/sysfs-class-net | 24 ++++++++++++++++++++++++
 include/linux/netdevice.h                 |  6 ++++--
 include/uapi/linux/if_link.h              |  2 ++
 net/core/net-sysfs.c                      | 23 ++++++++++++++++++++++-
 net/core/rtnetlink.c                      | 13 +++++++++++--
 net/sched/sch_generic.c                   |  4 ++--
 6 files changed, 65 insertions(+), 7 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-class-net 
b/Documentation/ABI/testing/sysfs-class-net
index 6856da99b6f7..e4b0d5157305 100644
--- a/Documentation/ABI/testing/sysfs-class-net
+++ b/Documentation/ABI/testing/sysfs-class-net
@@ -259,3 +259,27 @@ Contact:   netdev@vger.kernel.org
 Description:
                Symbolic link to the PHY device this network device is attached
                to.
+
+What:          /sys/class/net/<iface/carrier_changes
+Date:          Mar 2014
+KernelVersion: 3.15
+Contact:       netdev@vger.kernel.org
+Description:
+               32-bit unsigned integer counting the number of times the link 
has
+               seen a change from UP to DOWN and vice versa
+
+What:          /sys/class/net/<iface/count_link_up
+Date:          Jan 2018
+KernelVersion: 4.16
+Contact:       netdev@vger.kernel.org
+Description:
+               32-bit unsigned integer counting the number of times the link 
has
+               been up
+
+What:          /sys/class/net/<iface/count_link_down
+Date:          Jan 2018
+KernelVersion: 4.16
+Contact:       netdev@vger.kernel.org
+Description:
+               32-bit unsigned integer counting the number of times the link 
has
+               been down
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index ed0799a12bf2..28f68f7513d0 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1680,8 +1680,6 @@ struct net_device {
        unsigned long           base_addr;
        int                     irq;
 
-       atomic_t                carrier_changes;
-
        /*
         *      Some hardware also needs these fields (state,dev_list,
         *      napi_list,unreg_list,close_list) but they are not
@@ -1719,6 +1717,10 @@ struct net_device {
        atomic_long_t           tx_dropped;
        atomic_long_t           rx_nohandler;
 
+       /* Stats to monitor link on/off, flapping */
+       atomic_t                count_link_up;
+       atomic_t                count_link_down;
+
 #ifdef CONFIG_WIRELESS_EXT
        const struct iw_handler_def *wireless_handlers;
        struct iw_public_data   *wireless_data;
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index f8f04fed6186..6e44b0674ba4 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -161,6 +161,8 @@ enum {
        IFLA_EVENT,
        IFLA_NEW_NETNSID,
        IFLA_IF_NETNSID,
+       IFLA_COUNT_LINK_UP,
+       IFLA_COUNT_LINK_DOWN,
        __IFLA_MAX
 };
 
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 7bf8b85ade16..9f732c3dc2ce 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -295,10 +295,29 @@ static ssize_t carrier_changes_show(struct device *dev,
        struct net_device *netdev = to_net_dev(dev);
 
        return sprintf(buf, fmt_dec,
-                      atomic_read(&netdev->carrier_changes));
+                      atomic_read(&netdev->count_link_up) +
+                      atomic_read(&netdev->count_link_down));
 }
 static DEVICE_ATTR_RO(carrier_changes);
 
+static ssize_t count_link_up_show(struct device *dev,
+                                 struct device_attribute *attr, char *buf)
+{
+       struct net_device *netdev = to_net_dev(dev);
+
+       return sprintf(buf, fmt_dec, atomic_read(&netdev->count_link_up));
+}
+static DEVICE_ATTR_RO(count_link_up);
+
+static ssize_t count_link_down_show(struct device *dev,
+                                   struct device_attribute *attr, char *buf)
+{
+       struct net_device *netdev = to_net_dev(dev);
+
+       return sprintf(buf, fmt_dec, atomic_read(&netdev->count_link_down));
+}
+static DEVICE_ATTR_RO(count_link_down);
+
 /* read-write attributes */
 
 static int change_mtu(struct net_device *dev, unsigned long new_mtu)
@@ -547,6 +566,8 @@ static struct attribute *net_class_attrs[] __ro_after_init 
= {
        &dev_attr_phys_port_name.attr,
        &dev_attr_phys_switch_id.attr,
        &dev_attr_proto_down.attr,
+       &dev_attr_count_link_up.attr,
+       &dev_attr_count_link_down.attr,
        NULL,
 };
 ATTRIBUTE_GROUPS(net_class);
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 16d644a4f974..68f69a956713 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -990,6 +990,8 @@ static noinline size_t if_nlmsg_size(const struct 
net_device *dev,
               + nla_total_size(4)  /* IFLA_NEW_NETNSID */
               + nla_total_size(1)  /* IFLA_PROTO_DOWN */
               + nla_total_size(4)  /* IFLA_IF_NETNSID */
+              + nla_total_size(4)  /* IFLA_COUNT_LINK_UP */
+              + nla_total_size(4)  /* IFLA_COUNT_LINK_DOWN */
               + 0;
 }
 
@@ -1551,8 +1553,13 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
             nla_put_string(skb, IFLA_QDISC, dev->qdisc->ops->id)) ||
            nla_put_ifalias(skb, dev) ||
            nla_put_u32(skb, IFLA_CARRIER_CHANGES,
-                       atomic_read(&dev->carrier_changes)) ||
-           nla_put_u8(skb, IFLA_PROTO_DOWN, dev->proto_down))
+                       atomic_read(&dev->count_link_up) +
+                       atomic_read(&dev->count_link_down)) ||
+           nla_put_u8(skb, IFLA_PROTO_DOWN, dev->proto_down) ||
+           nla_put_u32(skb, IFLA_COUNT_LINK_UP,
+                       atomic_read(&dev->count_link_up)) ||
+           nla_put_u32(skb, IFLA_COUNT_LINK_DOWN,
+                       atomic_read(&dev->count_link_down)))
                goto nla_put_failure;
 
        if (event != IFLA_EVENT_NONE) {
@@ -1656,6 +1663,8 @@ static const struct nla_policy ifla_policy[IFLA_MAX+1] = {
        [IFLA_EVENT]            = { .type = NLA_U32 },
        [IFLA_GROUP]            = { .type = NLA_U32 },
        [IFLA_IF_NETNSID]       = { .type = NLA_S32 },
+       [IFLA_COUNT_LINK_UP]    = { .type = NLA_U32 },
+       [IFLA_COUNT_LINK_DOWN]  = { .type = NLA_U32 },
 };
 
 static const struct nla_policy ifla_info_policy[IFLA_INFO_MAX+1] = {
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index ef8b4ecde2ac..28941636afa3 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -510,7 +510,7 @@ void netif_carrier_on(struct net_device *dev)
        if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
                if (dev->reg_state == NETREG_UNINITIALIZED)
                        return;
-               atomic_inc(&dev->carrier_changes);
+               atomic_inc(&dev->count_link_up);
                linkwatch_fire_event(dev);
                if (netif_running(dev))
                        __netdev_watchdog_up(dev);
@@ -529,7 +529,7 @@ void netif_carrier_off(struct net_device *dev)
        if (!test_and_set_bit(__LINK_STATE_NOCARRIER, &dev->state)) {
                if (dev->reg_state == NETREG_UNINITIALIZED)
                        return;
-               atomic_inc(&dev->carrier_changes);
+               atomic_inc(&dev->count_link_down);
                linkwatch_fire_event(dev);
        }
 }
-- 
2.14.1

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