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70c69274f3
The timer and work item are currently initialized once during module init, but subsequent patches will need to associate different functions with the work item, based on the configured alert mode. Allow subsequent patches to make that change by initializing and de-initializing these objects during tracing enable and disable. This also guarantees that once the request to disable tracing returns, no more netlink notifications will be generated. Signed-off-by: Ido Schimmel <idosch@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
522 lines
12 KiB
C
522 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Monitoring code for network dropped packet alerts
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*
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* Copyright (C) 2009 Neil Horman <nhorman@tuxdriver.com>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/netdevice.h>
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#include <linux/etherdevice.h>
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#include <linux/string.h>
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#include <linux/if_arp.h>
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#include <linux/inetdevice.h>
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#include <linux/inet.h>
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#include <linux/interrupt.h>
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#include <linux/netpoll.h>
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#include <linux/sched.h>
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#include <linux/delay.h>
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#include <linux/types.h>
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#include <linux/workqueue.h>
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#include <linux/netlink.h>
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#include <linux/net_dropmon.h>
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#include <linux/percpu.h>
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#include <linux/timer.h>
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#include <linux/bitops.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <net/genetlink.h>
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#include <net/netevent.h>
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#include <trace/events/skb.h>
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#include <trace/events/napi.h>
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#include <asm/unaligned.h>
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#define TRACE_ON 1
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#define TRACE_OFF 0
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/*
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* Globals, our netlink socket pointer
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* and the work handle that will send up
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* netlink alerts
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*/
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static int trace_state = TRACE_OFF;
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/* net_dm_mutex
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*
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* An overall lock guarding every operation coming from userspace.
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* It also guards the global 'hw_stats_list' list.
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*/
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static DEFINE_MUTEX(net_dm_mutex);
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struct per_cpu_dm_data {
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spinlock_t lock; /* Protects 'skb' and 'send_timer' */
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struct sk_buff *skb;
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struct work_struct dm_alert_work;
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struct timer_list send_timer;
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};
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struct dm_hw_stat_delta {
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struct net_device *dev;
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unsigned long last_rx;
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struct list_head list;
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struct rcu_head rcu;
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unsigned long last_drop_val;
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};
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static struct genl_family net_drop_monitor_family;
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static DEFINE_PER_CPU(struct per_cpu_dm_data, dm_cpu_data);
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static int dm_hit_limit = 64;
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static int dm_delay = 1;
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static unsigned long dm_hw_check_delta = 2*HZ;
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static LIST_HEAD(hw_stats_list);
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static struct sk_buff *reset_per_cpu_data(struct per_cpu_dm_data *data)
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{
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size_t al;
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struct net_dm_alert_msg *msg;
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struct nlattr *nla;
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struct sk_buff *skb;
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unsigned long flags;
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void *msg_header;
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al = sizeof(struct net_dm_alert_msg);
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al += dm_hit_limit * sizeof(struct net_dm_drop_point);
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al += sizeof(struct nlattr);
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skb = genlmsg_new(al, GFP_KERNEL);
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if (!skb)
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goto err;
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msg_header = genlmsg_put(skb, 0, 0, &net_drop_monitor_family,
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0, NET_DM_CMD_ALERT);
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if (!msg_header) {
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nlmsg_free(skb);
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skb = NULL;
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goto err;
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}
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nla = nla_reserve(skb, NLA_UNSPEC,
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sizeof(struct net_dm_alert_msg));
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if (!nla) {
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nlmsg_free(skb);
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skb = NULL;
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goto err;
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}
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msg = nla_data(nla);
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memset(msg, 0, al);
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goto out;
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err:
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mod_timer(&data->send_timer, jiffies + HZ / 10);
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out:
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spin_lock_irqsave(&data->lock, flags);
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swap(data->skb, skb);
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spin_unlock_irqrestore(&data->lock, flags);
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if (skb) {
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struct nlmsghdr *nlh = (struct nlmsghdr *)skb->data;
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struct genlmsghdr *gnlh = (struct genlmsghdr *)nlmsg_data(nlh);
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genlmsg_end(skb, genlmsg_data(gnlh));
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}
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return skb;
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}
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static const struct genl_multicast_group dropmon_mcgrps[] = {
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{ .name = "events", },
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};
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static void send_dm_alert(struct work_struct *work)
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{
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struct sk_buff *skb;
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struct per_cpu_dm_data *data;
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data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
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skb = reset_per_cpu_data(data);
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if (skb)
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genlmsg_multicast(&net_drop_monitor_family, skb, 0,
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0, GFP_KERNEL);
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}
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/*
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* This is the timer function to delay the sending of an alert
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* in the event that more drops will arrive during the
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* hysteresis period.
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*/
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static void sched_send_work(struct timer_list *t)
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{
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struct per_cpu_dm_data *data = from_timer(data, t, send_timer);
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schedule_work(&data->dm_alert_work);
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}
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static void trace_drop_common(struct sk_buff *skb, void *location)
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{
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struct net_dm_alert_msg *msg;
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struct nlmsghdr *nlh;
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struct nlattr *nla;
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int i;
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struct sk_buff *dskb;
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struct per_cpu_dm_data *data;
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unsigned long flags;
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local_irq_save(flags);
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data = this_cpu_ptr(&dm_cpu_data);
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spin_lock(&data->lock);
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dskb = data->skb;
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if (!dskb)
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goto out;
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nlh = (struct nlmsghdr *)dskb->data;
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nla = genlmsg_data(nlmsg_data(nlh));
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msg = nla_data(nla);
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for (i = 0; i < msg->entries; i++) {
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if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
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msg->points[i].count++;
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goto out;
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}
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}
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if (msg->entries == dm_hit_limit)
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goto out;
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/*
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* We need to create a new entry
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*/
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__nla_reserve_nohdr(dskb, sizeof(struct net_dm_drop_point));
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nla->nla_len += NLA_ALIGN(sizeof(struct net_dm_drop_point));
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memcpy(msg->points[msg->entries].pc, &location, sizeof(void *));
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msg->points[msg->entries].count = 1;
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msg->entries++;
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if (!timer_pending(&data->send_timer)) {
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data->send_timer.expires = jiffies + dm_delay * HZ;
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add_timer(&data->send_timer);
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}
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out:
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spin_unlock_irqrestore(&data->lock, flags);
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}
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static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location)
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{
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trace_drop_common(skb, location);
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}
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static void trace_napi_poll_hit(void *ignore, struct napi_struct *napi,
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int work, int budget)
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{
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struct dm_hw_stat_delta *new_stat;
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/*
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* Don't check napi structures with no associated device
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*/
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if (!napi->dev)
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return;
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rcu_read_lock();
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list_for_each_entry_rcu(new_stat, &hw_stats_list, list) {
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/*
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* only add a note to our monitor buffer if:
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* 1) this is the dev we received on
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* 2) its after the last_rx delta
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* 3) our rx_dropped count has gone up
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*/
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if ((new_stat->dev == napi->dev) &&
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(time_after(jiffies, new_stat->last_rx + dm_hw_check_delta)) &&
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(napi->dev->stats.rx_dropped != new_stat->last_drop_val)) {
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trace_drop_common(NULL, NULL);
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new_stat->last_drop_val = napi->dev->stats.rx_dropped;
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new_stat->last_rx = jiffies;
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break;
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}
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}
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rcu_read_unlock();
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}
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static int net_dm_trace_on_set(struct netlink_ext_ack *extack)
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{
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int cpu, rc;
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if (!try_module_get(THIS_MODULE)) {
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NL_SET_ERR_MSG_MOD(extack, "Failed to take reference on module");
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return -ENODEV;
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}
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for_each_possible_cpu(cpu) {
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struct per_cpu_dm_data *data = &per_cpu(dm_cpu_data, cpu);
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INIT_WORK(&data->dm_alert_work, send_dm_alert);
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timer_setup(&data->send_timer, sched_send_work, 0);
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}
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rc = register_trace_kfree_skb(trace_kfree_skb_hit, NULL);
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if (rc) {
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NL_SET_ERR_MSG_MOD(extack, "Failed to connect probe to kfree_skb() tracepoint");
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goto err_module_put;
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}
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rc = register_trace_napi_poll(trace_napi_poll_hit, NULL);
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if (rc) {
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NL_SET_ERR_MSG_MOD(extack, "Failed to connect probe to napi_poll() tracepoint");
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goto err_unregister_trace;
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}
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return 0;
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err_unregister_trace:
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unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL);
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err_module_put:
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module_put(THIS_MODULE);
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return rc;
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}
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static void net_dm_trace_off_set(void)
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{
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struct dm_hw_stat_delta *new_stat, *temp;
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int cpu;
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unregister_trace_napi_poll(trace_napi_poll_hit, NULL);
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unregister_trace_kfree_skb(trace_kfree_skb_hit, NULL);
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tracepoint_synchronize_unregister();
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/* Make sure we do not send notifications to user space after request
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* to stop tracing returns.
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*/
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for_each_possible_cpu(cpu) {
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struct per_cpu_dm_data *data = &per_cpu(dm_cpu_data, cpu);
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del_timer_sync(&data->send_timer);
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cancel_work_sync(&data->dm_alert_work);
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}
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list_for_each_entry_safe(new_stat, temp, &hw_stats_list, list) {
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if (new_stat->dev == NULL) {
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list_del_rcu(&new_stat->list);
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kfree_rcu(new_stat, rcu);
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}
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}
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module_put(THIS_MODULE);
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}
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static int set_all_monitor_traces(int state, struct netlink_ext_ack *extack)
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{
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int rc = 0;
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if (state == trace_state) {
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NL_SET_ERR_MSG_MOD(extack, "Trace state already set to requested state");
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return -EAGAIN;
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}
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switch (state) {
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case TRACE_ON:
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rc = net_dm_trace_on_set(extack);
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break;
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case TRACE_OFF:
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net_dm_trace_off_set();
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break;
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default:
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rc = 1;
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break;
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}
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if (!rc)
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trace_state = state;
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else
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rc = -EINPROGRESS;
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return rc;
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}
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static int net_dm_cmd_config(struct sk_buff *skb,
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struct genl_info *info)
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{
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NL_SET_ERR_MSG_MOD(info->extack, "Command not supported");
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return -EOPNOTSUPP;
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}
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static int net_dm_cmd_trace(struct sk_buff *skb,
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struct genl_info *info)
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{
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switch (info->genlhdr->cmd) {
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case NET_DM_CMD_START:
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return set_all_monitor_traces(TRACE_ON, info->extack);
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case NET_DM_CMD_STOP:
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return set_all_monitor_traces(TRACE_OFF, info->extack);
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}
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return -EOPNOTSUPP;
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}
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static int dropmon_net_event(struct notifier_block *ev_block,
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unsigned long event, void *ptr)
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{
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struct net_device *dev = netdev_notifier_info_to_dev(ptr);
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struct dm_hw_stat_delta *new_stat = NULL;
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struct dm_hw_stat_delta *tmp;
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switch (event) {
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case NETDEV_REGISTER:
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new_stat = kzalloc(sizeof(struct dm_hw_stat_delta), GFP_KERNEL);
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if (!new_stat)
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goto out;
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new_stat->dev = dev;
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new_stat->last_rx = jiffies;
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mutex_lock(&net_dm_mutex);
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list_add_rcu(&new_stat->list, &hw_stats_list);
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mutex_unlock(&net_dm_mutex);
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break;
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case NETDEV_UNREGISTER:
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mutex_lock(&net_dm_mutex);
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list_for_each_entry_safe(new_stat, tmp, &hw_stats_list, list) {
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if (new_stat->dev == dev) {
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new_stat->dev = NULL;
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if (trace_state == TRACE_OFF) {
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list_del_rcu(&new_stat->list);
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kfree_rcu(new_stat, rcu);
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break;
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}
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}
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}
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mutex_unlock(&net_dm_mutex);
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break;
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}
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out:
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return NOTIFY_DONE;
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}
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static const struct genl_ops dropmon_ops[] = {
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{
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.cmd = NET_DM_CMD_CONFIG,
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.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
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.doit = net_dm_cmd_config,
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},
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{
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.cmd = NET_DM_CMD_START,
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.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
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.doit = net_dm_cmd_trace,
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},
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{
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.cmd = NET_DM_CMD_STOP,
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.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
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.doit = net_dm_cmd_trace,
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},
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};
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static int net_dm_nl_pre_doit(const struct genl_ops *ops,
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struct sk_buff *skb, struct genl_info *info)
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{
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mutex_lock(&net_dm_mutex);
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return 0;
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}
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static void net_dm_nl_post_doit(const struct genl_ops *ops,
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struct sk_buff *skb, struct genl_info *info)
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{
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mutex_unlock(&net_dm_mutex);
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}
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static struct genl_family net_drop_monitor_family __ro_after_init = {
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.hdrsize = 0,
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.name = "NET_DM",
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.version = 2,
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.pre_doit = net_dm_nl_pre_doit,
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.post_doit = net_dm_nl_post_doit,
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.module = THIS_MODULE,
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.ops = dropmon_ops,
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.n_ops = ARRAY_SIZE(dropmon_ops),
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.mcgrps = dropmon_mcgrps,
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.n_mcgrps = ARRAY_SIZE(dropmon_mcgrps),
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};
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static struct notifier_block dropmon_net_notifier = {
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.notifier_call = dropmon_net_event
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};
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static int __init init_net_drop_monitor(void)
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{
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struct per_cpu_dm_data *data;
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int cpu, rc;
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pr_info("Initializing network drop monitor service\n");
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if (sizeof(void *) > 8) {
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pr_err("Unable to store program counters on this arch, Drop monitor failed\n");
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return -ENOSPC;
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}
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rc = genl_register_family(&net_drop_monitor_family);
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if (rc) {
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pr_err("Could not create drop monitor netlink family\n");
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return rc;
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}
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WARN_ON(net_drop_monitor_family.mcgrp_offset != NET_DM_GRP_ALERT);
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rc = register_netdevice_notifier(&dropmon_net_notifier);
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if (rc < 0) {
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pr_crit("Failed to register netdevice notifier\n");
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goto out_unreg;
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}
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rc = 0;
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for_each_possible_cpu(cpu) {
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data = &per_cpu(dm_cpu_data, cpu);
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INIT_WORK(&data->dm_alert_work, send_dm_alert);
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timer_setup(&data->send_timer, sched_send_work, 0);
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spin_lock_init(&data->lock);
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reset_per_cpu_data(data);
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}
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goto out;
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out_unreg:
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genl_unregister_family(&net_drop_monitor_family);
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out:
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return rc;
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}
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static void exit_net_drop_monitor(void)
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{
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struct per_cpu_dm_data *data;
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int cpu;
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BUG_ON(unregister_netdevice_notifier(&dropmon_net_notifier));
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/*
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* Because of the module_get/put we do in the trace state change path
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* we are guarnateed not to have any current users when we get here
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*/
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for_each_possible_cpu(cpu) {
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data = &per_cpu(dm_cpu_data, cpu);
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/*
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* At this point, we should have exclusive access
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* to this struct and can free the skb inside it
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*/
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kfree_skb(data->skb);
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}
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BUG_ON(genl_unregister_family(&net_drop_monitor_family));
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}
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module_init(init_net_drop_monitor);
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module_exit(exit_net_drop_monitor);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
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MODULE_ALIAS_GENL_FAMILY("NET_DM");
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