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Commit 5848cc09 authored by Neil Horman's avatar Neil Horman Committed by David S. Miller
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net: drop_monitor: make last_rx timestamp private 



It was recently pointed out to me that the last_rx field of the
net_device structure wasn't updated regularly.  In fact only the
bonding driver really uses it currently.  Since the drop_monitor code
relies on the last_rx field to detect drops on recevie in hardware, We
need to find a more reliable way to rate limit our drop checks (so
that we don't check for drops on every frame recevied, which would be
inefficient.  This patch makes a last_rx timestamp that is private to
the drop monitor code and is updated for every device that we track.

Signed-off-by: default avatarNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3f968de2

net/core/drop_monitor.c

+12 −3
Original line number Diff line number Diff line
@@ -52,6 +52,7 @@ struct per_cpu_dm_data { 


struct dm_hw_stat_delta {

	struct net_device *dev;

	unsigned long last_rx;

	struct list_head list;

	struct rcu_head rcu;

	unsigned long last_drop_val;
@@ -180,18 +181,25 @@ 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

	 * Don't check napi structures with no associated device

	 */

	if (!napi->dev ||

	    !time_after(jiffies, napi->dev->last_rx + dm_hw_check_delta))

	if (!napi->dev)

		return;



	rcu_read_lock();

	list_for_each_entry_rcu(new_stat, &hw_stats_list, list) {

		/*

		 * only add a note to our monitor buffer if:

		 * 1) this is the dev we received on

		 * 2) its after the last_rx delta

		 * 3) our rx_dropped count has gone up

		 */

		if ((new_stat->dev == napi->dev)  &&

		    (time_after(jiffies, new_stat->last_rx + dm_hw_check_delta)) &&

		    (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;

			new_stat->last_rx = jiffies;

			break;

		}

	}
@@ -287,6 +295,7 @@ static int dropmon_net_event(struct notifier_block *ev_block, 
			goto out;



		new_stat->dev = dev;

		new_stat->last_rx = jiffies;

		INIT_RCU_HEAD(&new_stat->rcu);

		spin_lock(&trace_state_lock);

		list_add_rcu(&new_stat->list, &hw_stats_list);