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Commit 9a6d276e authored by Neil Horman's avatar Neil Horman Committed by David S. Miller
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core: add stat to track unresolved discards in neighbor cache 



in __neigh_event_send, if we have a neighbour entry which is in
NUD_INCOMPLETE state, we enqueue any outbound frames to that neighbour
to the neighbours arp_queue, which is default capped to a length of 3
skbs.  If that queue exceeds its set length, it will drop an skb on
the queue to enqueue the newly arrived skb.  This results in a drop
for which we have no statistics incremented.  This patch adds an
unresolved_discards stat to /proc/net/stat/ndisc_cache to track these
lost frames.

Signed-off-by: default avatarNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ed88098e

include/net/neighbour.h

+3 −1
Original line number Diff line number Diff line
@@ -75,7 +75,7 @@ struct neigh_statistics 
	unsigned long destroys;		/* number of destroyed neighs */

	unsigned long hash_grows;	/* number of hash resizes */



	unsigned long res_failed;	/* nomber of failed resolutions */

	unsigned long res_failed;	/* number of failed resolutions */



	unsigned long lookups;		/* number of lookups */

	unsigned long hits;		/* number of hits (among lookups) */
@@ -85,6 +85,8 @@ struct neigh_statistics 


	unsigned long periodic_gc_runs;	/* number of periodic GC runs */

	unsigned long forced_gc_runs;	/* number of forced GC runs */



	unsigned long unres_discards;	/* number of unresolved drops */

};



#define NEIGH_CACHE_STAT_INC(tbl, field)				\

net/core/neighbour.c

+5 −3
Original line number Diff line number Diff line
@@ -930,6 +930,7 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb) 
				buff = neigh->arp_queue.next;

				__skb_unlink(buff, &neigh->arp_queue);

				kfree_skb(buff);

				NEIGH_CACHE_STAT_INC(neigh->tbl, unres_discards);

			}

			__skb_queue_tail(&neigh->arp_queue, skb);

		}
@@ -2462,12 +2463,12 @@ static int neigh_stat_seq_show(struct seq_file *seq, void *v) 
	struct neigh_statistics *st = v;



	if (v == SEQ_START_TOKEN) {

		seq_printf(seq, "entries  allocs destroys hash_grows  lookups hits  res_failed  rcv_probes_mcast rcv_probes_ucast  periodic_gc_runs forced_gc_runs\n");

		seq_printf(seq, "entries  allocs destroys hash_grows  lookups hits  res_failed  rcv_probes_mcast rcv_probes_ucast  periodic_gc_runs forced_gc_runs unresolved_discards\n");

		return 0;

	}



	seq_printf(seq, "%08x  %08lx %08lx %08lx  %08lx %08lx  %08lx  "

			"%08lx %08lx  %08lx %08lx\n",

			"%08lx %08lx  %08lx %08lx %08lx\n",

		   atomic_read(&tbl->entries),



		   st->allocs,
@@ -2483,7 +2484,8 @@ static int neigh_stat_seq_show(struct seq_file *seq, void *v) 
		   st->rcv_probes_ucast,



		   st->periodic_gc_runs,

		   st->forced_gc_runs

		   st->forced_gc_runs,

		   st->unres_discards

		   );



	return 0;