* Copyright (C) 2009 Neil Horman <nhorman@tuxdriver.com>
*/
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/bitops.h>
#include <linux/slab.h>
+#include <linux/module.h>
#include <net/genetlink.h>
#include <net/netevent.h>
* netlink alerts
*/
static int trace_state = TRACE_OFF;
-static DEFINE_SPINLOCK(trace_state_lock);
+static DEFINE_MUTEX(trace_state_mutex);
struct per_cpu_dm_data {
struct work_struct dm_alert_work;
- struct sk_buff *skb;
+ struct sk_buff __rcu *skb;
atomic_t dm_hit_count;
struct timer_list send_timer;
+ int cpu;
};
struct dm_hw_stat_delta {
size_t al;
struct net_dm_alert_msg *msg;
struct nlattr *nla;
+ struct sk_buff *skb;
+ struct sk_buff *oskb = rcu_dereference_protected(data->skb, 1);
al = sizeof(struct net_dm_alert_msg);
al += dm_hit_limit * sizeof(struct net_dm_drop_point);
al += sizeof(struct nlattr);
- data->skb = genlmsg_new(al, GFP_KERNEL);
- genlmsg_put(data->skb, 0, 0, &net_drop_monitor_family,
- 0, NET_DM_CMD_ALERT);
- nla = nla_reserve(data->skb, NLA_UNSPEC, sizeof(struct net_dm_alert_msg));
- msg = nla_data(nla);
- memset(msg, 0, al);
- atomic_set(&data->dm_hit_count, dm_hit_limit);
+ skb = genlmsg_new(al, GFP_KERNEL);
+
+ if (skb) {
+ genlmsg_put(skb, 0, 0, &net_drop_monitor_family,
+ 0, NET_DM_CMD_ALERT);
+ nla = nla_reserve(skb, NLA_UNSPEC,
+ sizeof(struct net_dm_alert_msg));
+ msg = nla_data(nla);
+ memset(msg, 0, al);
+ } else
+ schedule_work_on(data->cpu, &data->dm_alert_work);
+
+ /*
+ * Don't need to lock this, since we are guaranteed to only
+ * run this on a single cpu at a time.
+ * Note also that we only update data->skb if the old and new skb
+ * pointers don't match. This ensures that we don't continually call
+ * synchornize_rcu if we repeatedly fail to alloc a new netlink message.
+ */
+ if (skb != oskb) {
+ rcu_assign_pointer(data->skb, skb);
+
+ synchronize_rcu();
+
+ atomic_set(&data->dm_hit_count, dm_hit_limit);
+ }
+
}
static void send_dm_alert(struct work_struct *unused)
{
struct sk_buff *skb;
- struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);
+ struct per_cpu_dm_data *data = &get_cpu_var(dm_cpu_data);
+
+ WARN_ON_ONCE(data->cpu != smp_processor_id());
/*
* Grab the skb we're about to send
*/
- skb = data->skb;
+ skb = rcu_dereference_protected(data->skb, 1);
/*
* Replace it with a new one
/*
* Ship it!
*/
- genlmsg_multicast(skb, 0, NET_DM_GRP_ALERT, GFP_KERNEL);
+ if (skb)
+ genlmsg_multicast(skb, 0, NET_DM_GRP_ALERT, GFP_KERNEL);
+ put_cpu_var(dm_cpu_data);
}
/*
*/
static void sched_send_work(unsigned long unused)
{
- struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);
+ struct per_cpu_dm_data *data = &get_cpu_var(dm_cpu_data);
+
+ schedule_work_on(smp_processor_id(), &data->dm_alert_work);
- schedule_work(&data->dm_alert_work);
+ put_cpu_var(dm_cpu_data);
}
static void trace_drop_common(struct sk_buff *skb, void *location)
struct nlmsghdr *nlh;
struct nlattr *nla;
int i;
- struct per_cpu_dm_data *data = &__get_cpu_var(dm_cpu_data);
+ struct sk_buff *dskb;
+ struct per_cpu_dm_data *data = &get_cpu_var(dm_cpu_data);
+ rcu_read_lock();
+ dskb = rcu_dereference(data->skb);
+
+ if (!dskb)
+ goto out;
+
if (!atomic_add_unless(&data->dm_hit_count, -1, 0)) {
/*
* we're already at zero, discard this hit
goto out;
}
- nlh = (struct nlmsghdr *)data->skb->data;
+ nlh = (struct nlmsghdr *)dskb->data;
nla = genlmsg_data(nlmsg_data(nlh));
msg = nla_data(nla);
for (i = 0; i < msg->entries; i++) {
/*
* We need to create a new entry
*/
- __nla_reserve_nohdr(data->skb, sizeof(struct net_dm_drop_point));
+ __nla_reserve_nohdr(dskb, sizeof(struct net_dm_drop_point));
nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point));
memcpy(msg->points[msg->entries].pc, &location, sizeof(void *));
msg->points[msg->entries].count = 1;
}
out:
+ rcu_read_unlock();
+ put_cpu_var(dm_cpu_data);
return;
}
struct dm_hw_stat_delta *new_stat = NULL;
struct dm_hw_stat_delta *temp;
- spin_lock(&trace_state_lock);
+ mutex_lock(&trace_state_mutex);
if (state == trace_state) {
rc = -EAGAIN;
switch (state) {
case TRACE_ON:
+ if (!try_module_get(THIS_MODULE)) {
+ rc = -ENODEV;
+ break;
+ }
+
rc |= register_trace_kfree_skb(trace_kfree_skb_hit, NULL);
rc |= register_trace_napi_poll(trace_napi_poll_hit, NULL);
break;
+
case TRACE_OFF:
rc |= unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL);
rc |= unregister_trace_napi_poll(trace_napi_poll_hit, NULL);
kfree_rcu(new_stat, rcu);
}
}
+
+ module_put(THIS_MODULE);
+
break;
default:
rc = 1;
rc = -EINPROGRESS;
out_unlock:
- spin_unlock(&trace_state_lock);
+ mutex_unlock(&trace_state_mutex);
return rc;
}
new_stat->dev = dev;
new_stat->last_rx = jiffies;
- spin_lock(&trace_state_lock);
+ mutex_lock(&trace_state_mutex);
list_add_rcu(&new_stat->list, &hw_stats_list);
- spin_unlock(&trace_state_lock);
+ mutex_unlock(&trace_state_mutex);
break;
case NETDEV_UNREGISTER:
- spin_lock(&trace_state_lock);
+ mutex_lock(&trace_state_mutex);
list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) {
if (new_stat->dev == dev) {
new_stat->dev = NULL;
}
}
}
- spin_unlock(&trace_state_lock);
+ mutex_unlock(&trace_state_mutex);
break;
}
out:
struct per_cpu_dm_data *data;
int cpu, rc;
- printk(KERN_INFO "Initializing network drop monitor service\n");
+ pr_info("Initializing network drop monitor service\n");
if (sizeof(void *) > 8) {
- printk(KERN_ERR "Unable to store program counters on this arch, Drop monitor failed\n");
+ pr_err("Unable to store program counters on this arch, Drop monitor failed\n");
return -ENOSPC;
}
dropmon_ops,
ARRAY_SIZE(dropmon_ops));
if (rc) {
- printk(KERN_ERR "Could not create drop monitor netlink family\n");
+ pr_err("Could not create drop monitor netlink family\n");
return rc;
}
rc = register_netdevice_notifier(&dropmon_net_notifier);
if (rc < 0) {
- printk(KERN_CRIT "Failed to register netdevice notifier\n");
+ pr_crit("Failed to register netdevice notifier\n");
goto out_unreg;
}
rc = 0;
- for_each_present_cpu(cpu) {
+ for_each_possible_cpu(cpu) {
data = &per_cpu(dm_cpu_data, cpu);
- reset_per_cpu_data(data);
+ data->cpu = cpu;
INIT_WORK(&data->dm_alert_work, send_dm_alert);
init_timer(&data->send_timer);
data->send_timer.data = cpu;
data->send_timer.function = sched_send_work;
+ reset_per_cpu_data(data);
}
+
goto out;
out_unreg:
return rc;
}
-late_initcall(init_net_drop_monitor);
+static void exit_net_drop_monitor(void)
+{
+ struct per_cpu_dm_data *data;
+ int cpu;
+
+ BUG_ON(unregister_netdevice_notifier(&dropmon_net_notifier));
+
+ /*
+ * Because of the module_get/put we do in the trace state change path
+ * we are guarnateed not to have any current users when we get here
+ * all we need to do is make sure that we don't have any running timers
+ * or pending schedule calls
+ */
+
+ for_each_possible_cpu(cpu) {
+ data = &per_cpu(dm_cpu_data, cpu);
+ del_timer_sync(&data->send_timer);
+ cancel_work_sync(&data->dm_alert_work);
+ /*
+ * At this point, we should have exclusive access
+ * to this struct and can free the skb inside it
+ */
+ kfree_skb(data->skb);
+ }
+
+ BUG_ON(genl_unregister_family(&net_drop_monitor_family));
+}
+
+module_init(init_net_drop_monitor);
+module_exit(exit_net_drop_monitor);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
projects / karo-tx-linux.git / blobdiff