dropmon: add ability to detect when hardware dropsrxpackets

Patch to add the ability to detect drops in hardware interfaces via dropwatch.
Adds a tracepoint to net_rx_action to signal everytime a napi instance is
polled.  The dropmon code then periodically checks to see if the rx_frames
counter has changed, and if so, adds a drop notification to the netlink
protocol, using the reserved all-0's vector to indicate the drop location was in
hardware, rather than somewhere in the code.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>

 include/linux/net_dropmon.h |    8 ++
 include/trace/napi.h        |   11 +++
 net/core/dev.c              |    5 +
 net/core/drop_monitor.c     |  124 ++++++++++++++++++++++++++++++++++++++++++--
 net/core/net-traces.c       |    4 +
 net/core/netpoll.c          |    2
 6 files changed, 149 insertions(+), 5 deletions(-)
Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 149 insertions, 5 deletions

diff --git a/include/linux/net_dropmon.h b/include/linux/net_dropmon.h
index 0217fb81a630..e8a8b5c50ed0 100644
--- a/include/linux/net_dropmon.h
+++ b/include/linux/net_dropmon.h
@@ -2,12 +2,20 @@
 #define __NET_DROPMON_H
 
 #include <linux/netlink.h>
+#include <linux/types.h>
 
 struct net_dm_drop_point {
         __u8 pc[8];
         __u32 count;
 };
 
+#define is_drop_point_hw(x) do {\
+        int ____i, ____j;\
+        for (____i = 0; ____i < 8; i ____i++)\
+                ____j |= x[____i];\
+        ____j;\
+} while (0)
+
 #define NET_DM_CFG_VERSION  0
 #define NET_DM_CFG_ALERT_COUNT  1
 #define NET_DM_CFG_ALERT_DELAY 2
diff --git a/include/trace/napi.h b/include/trace/napi.h
new file mode 100644
index 000000000000..a8989c4547e7
--- /dev/null
+++ b/include/trace/napi.h
@@ -0,0 +1,11 @@
+#ifndef _TRACE_NAPI_H_
+#define _TRACE_NAPI_H_
+
+#include <linux/netdevice.h>
+#include <linux/tracepoint.h>
+
+DECLARE_TRACE(napi_poll,
+        TP_PROTO(struct napi_struct *napi),
+        TP_ARGS(napi));
+
+#endif
diff --git a/net/core/dev.c b/net/core/dev.c
index 92ebeca29901..3942266d1f6c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -126,6 +126,7 @@
 #include <linux/in.h>
 #include <linux/jhash.h>
 #include <linux/random.h>
+#include <trace/napi.h>
 
 #include "net-sysfs.h"
 
@@ -2771,8 +2772,10 @@ static void net_rx_action(struct softirq_action *h)
                  * accidently calling ->poll() when NAPI is not scheduled.
                  */
                 work = 0;
-                if (test_bit(NAPI_STATE_SCHED, &n->state))
+                if (test_bit(NAPI_STATE_SCHED, &n->state)) {
                         work = n->poll(n, weight);
+                        trace_napi_poll(n);
+                }
 
                 WARN_ON_ONCE(work > weight);
 
diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
index 2797b711a978..a6c2ac2828fb 100644
--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -22,8 +22,10 @@
 #include <linux/timer.h>
 #include <linux/bitops.h>
 #include <net/genetlink.h>
+#include <net/netevent.h>
 
 #include <trace/skb.h>
+#include <trace/napi.h>
 
 #include <asm/unaligned.h>
 
@@ -38,7 +40,8 @@ static void send_dm_alert(struct work_struct *unused);
  * and the work handle that will send up
  * netlink alerts
  */
-struct sock *dm_sock;
+static int trace_state = TRACE_OFF;
+static spinlock_t trace_state_lock = SPIN_LOCK_UNLOCKED;
 
 struct per_cpu_dm_data {
         struct work_struct dm_alert_work;
@@ -47,6 +50,13 @@ struct per_cpu_dm_data {
         struct timer_list send_timer;
 };
 
+struct dm_hw_stat_delta {
+        struct net_device *dev;
+        struct list_head list;
+        struct rcu_head rcu;
+        unsigned long last_drop_val;
+};
+
 static struct genl_family net_drop_monitor_family = {
         .id             = GENL_ID_GENERATE,
         .hdrsize        = 0,
@@ -59,7 +69,8 @@ static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data);
 
 static int dm_hit_limit = 64;
 static int dm_delay = 1;
-
+static unsigned long dm_hw_check_delta = 2*HZ;
+static LIST_HEAD(hw_stats_list);
 
 static void reset_per_cpu_data(struct per_cpu_dm_data *data)
 {
@@ -115,7 +126,7 @@ static void sched_send_work(unsigned long unused)
         schedule_work(&data->dm_alert_work);
 }
 
-static void trace_kfree_skb_hit(struct sk_buff *skb, void *location)
+static void trace_drop_common(struct sk_buff *skb, void *location)
 {
         struct net_dm_alert_msg *msg;
         struct nlmsghdr *nlh;
@@ -159,24 +170,80 @@ out:
         return;
 }
 
+static void trace_kfree_skb_hit(struct sk_buff *skb, void *location)
+{
+        trace_drop_common(skb, location);
+}
+
+static void trace_napi_poll_hit(struct napi_struct *napi)
+{
+        struct dm_hw_stat_delta *new_stat;
+
+        /*
+         * Ratelimit our check time to dm_hw_check_delta jiffies
+         */
+        if (!time_after(jiffies, napi->dev->last_rx + dm_hw_check_delta))
+                return;
+
+        rcu_read_lock();
+        list_for_each_entry_rcu(new_stat, &hw_stats_list, list) {
+                if ((new_stat->dev == napi->dev)  &&
+                    (napi->dev->stats.rx_dropped != new_stat->last_drop_val)) {
+                        trace_drop_common(NULL, NULL);
+                        new_stat->last_drop_val = napi->dev->stats.rx_dropped;
+                        break;
+                }
+        }
+        rcu_read_unlock();
+}
+
+
+static void free_dm_hw_stat(struct rcu_head *head)
+{
+        struct dm_hw_stat_delta *n;
+        n = container_of(head, struct dm_hw_stat_delta, rcu);
+        kfree(n);
+}
+
 static int set_all_monitor_traces(int state)
 {
         int rc = 0;
+        struct dm_hw_stat_delta *new_stat = NULL;
+        struct dm_hw_stat_delta *temp;
+
+        spin_lock(&trace_state_lock);
 
         switch (state) {
         case TRACE_ON:
                 rc |= register_trace_kfree_skb(trace_kfree_skb_hit);
+                rc |= register_trace_napi_poll(trace_napi_poll_hit);
                 break;
         case TRACE_OFF:
                 rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit);
+                rc |= unregister_trace_napi_poll(trace_napi_poll_hit);
 
                 tracepoint_synchronize_unregister();
+
+                /*
+                 * Clean the device list
+                 */
+                list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) {
+                        if (new_stat->dev == NULL) {
+                                list_del_rcu(&new_stat->list);
+                                call_rcu(&new_stat->rcu, free_dm_hw_stat);
+                        }
+                }
                 break;
         default:
                 rc = 1;
                 break;
         }
 
+        if (!rc)
+                trace_state = state;
+
+        spin_unlock(&trace_state_lock);
+
         if (rc)
                 return -EINPROGRESS;
         return rc;
@@ -204,6 +271,44 @@ static int net_dm_cmd_trace(struct sk_buff *skb,
         return -ENOTSUPP;
 }
 
+static int dropmon_net_event(struct notifier_block *ev_block,
+                        unsigned long event, void *ptr)
+{
+        struct net_device *dev = ptr;
+        struct dm_hw_stat_delta *new_stat = NULL;
+        struct dm_hw_stat_delta *tmp;
+
+        switch (event) {
+        case NETDEV_REGISTER:
+                new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL);
+
+                if (!new_stat)
+                        goto out;
+
+                new_stat->dev = dev;
+                INIT_RCU_HEAD(&new_stat->rcu);
+                spin_lock(&trace_state_lock);
+                list_add_rcu(&new_stat->list, &hw_stats_list);
+                spin_unlock(&trace_state_lock);
+                break;
+        case NETDEV_UNREGISTER:
+                spin_lock(&trace_state_lock);
+                list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) {
+                        if (new_stat->dev == dev) {
+                                new_stat->dev = NULL;
+                                if (trace_state == TRACE_OFF) {
+                                        list_del_rcu(&new_stat->list);
+                                        call_rcu(&new_stat->rcu, free_dm_hw_stat);
+                                        break;
+                                }
+                        }
+                }
+                spin_unlock(&trace_state_lock);
+                break;
+        }
+out:
+        return NOTIFY_DONE;
+}
 
 static struct genl_ops dropmon_ops[] = {
         {
@@ -220,6 +325,10 @@ static struct genl_ops dropmon_ops[] = {
         },
 };
 
+static struct notifier_block dropmon_net_notifier = {
+        .notifier_call = dropmon_net_event
+};
+
 static int __init init_net_drop_monitor(void)
 {
         int cpu;
@@ -243,12 +352,18 @@ static int __init init_net_drop_monitor(void)
                 ret = genl_register_ops(&net_drop_monitor_family,
                                         &dropmon_ops[i]);
                 if (ret) {
-                        printk(KERN_CRIT "failed to register operation %d\n",
+                        printk(KERN_CRIT "Failed to register operation %d\n",
                                 dropmon_ops[i].cmd);
                         goto out_unreg;
                 }
         }
 
+        rc = register_netdevice_notifier(&dropmon_net_notifier);
+        if (rc < 0) {
+                printk(KERN_CRIT "Failed to register netdevice notifier\n");
+                goto out_unreg;
+        }
+
         rc = 0;
 
         for_each_present_cpu(cpu) {
@@ -259,6 +374,7 @@ static int __init init_net_drop_monitor(void)
                 data->send_timer.data = cpu;
                 data->send_timer.function = sched_send_work;
         }
+
         goto out;
 
 out_unreg:
diff --git a/net/core/net-traces.c b/net/core/net-traces.c
index c8fb45665e4f..b07b25bd2cde 100644
--- a/net/core/net-traces.c
+++ b/net/core/net-traces.c
@@ -20,6 +20,7 @@
 #include <linux/netlink.h>
 #include <linux/net_dropmon.h>
 #include <trace/skb.h>
+#include <trace/napi.h>
 
 #include <asm/unaligned.h>
 #include <asm/bitops.h>
@@ -27,3 +28,6 @@
 
 DEFINE_TRACE(kfree_skb);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kfree_skb);
+
+DEFINE_TRACE(napi_poll);
+EXPORT_TRACEPOINT_SYMBOL_GPL(napi_poll);
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 64f51eec6576..00b14e2c50ed 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -24,6 +24,7 @@
 #include <net/tcp.h>
 #include <net/udp.h>
 #include <asm/unaligned.h>
+#include <trace/napi.h>
 
 /*
  * We maintain a small pool of fully-sized skbs, to make sure the
@@ -137,6 +138,7 @@ static int poll_one_napi(struct netpoll_info *npinfo,
         set_bit(NAPI_STATE_NPSVC, &napi->state);
 
         work = napi->poll(napi, budget);
+        trace_napi_poll(napi->dev);
 
         clear_bit(NAPI_STATE_NPSVC, &napi->state);
         atomic_dec(&trapped);