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Commit 75fbfd33 authored by Nicolas Dichtel's avatar Nicolas Dichtel Committed by David S. Miller
Browse files

neigh: optimize neigh_parms_release() 



In neigh_parms_release() we loop over all entries to find the entry given in
argument and being able to remove it from the list. By using a double linked
list, we can avoid this loop.

Here are some numbers with 30 000 dummy interfaces configured:

Before the patch:
$ time rmmod dummy
real	2m0.118s
user	0m0.000s
sys	1m50.048s

After the patch:
$ time rmmod dummy
real	1m9.970s
user	0m0.000s
sys	0m47.976s

Suggested-by: default avatarThierry Herbelot <thierry.herbelot@6wind.com>
Signed-off-by: default avatarNicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent bc9ad166

include/net/neighbour.h

+2 −1
Original line number Diff line number Diff line
@@ -69,7 +69,7 @@ struct neigh_parms { 
	struct net *net;

#endif

	struct net_device *dev;

	struct neigh_parms *next;

	struct list_head list;

	int	(*neigh_setup)(struct neighbour *);

	void	(*neigh_cleanup)(struct neighbour *);

	struct neigh_table *tbl;
@@ -203,6 +203,7 @@ struct neigh_table { 
	void			(*proxy_redo)(struct sk_buff *skb);

	char			*id;

	struct neigh_parms	parms;

	struct list_head	parms_list;

	int			gc_interval;

	int			gc_thresh1;

	int			gc_thresh2;

net/core/neighbour.c

+13 −19
Original line number Diff line number Diff line
@@ -773,7 +773,7 @@ static void neigh_periodic_work(struct work_struct *work) 
	if (time_after(jiffies, tbl->last_rand + 300 * HZ)) {

		struct neigh_parms *p;

		tbl->last_rand = jiffies;

		for (p = &tbl->parms; p; p = p->next)

		list_for_each_entry(p, &tbl->parms_list, list)

			p->reachable_time =

				neigh_rand_reach_time(NEIGH_VAR(p, BASE_REACHABLE_TIME));

	}
@@ -1446,7 +1446,7 @@ static inline struct neigh_parms *lookup_neigh_parms(struct neigh_table *tbl, 
{

	struct neigh_parms *p;



	for (p = &tbl->parms; p; p = p->next) {

	list_for_each_entry(p, &tbl->parms_list, list) {

		if ((p->dev && p->dev->ifindex == ifindex && net_eq(neigh_parms_net(p), net)) ||

		    (!p->dev && !ifindex && net_eq(net, &init_net)))

			return p;
@@ -1481,8 +1481,7 @@ struct neigh_parms *neigh_parms_alloc(struct net_device *dev, 
		}



		write_lock_bh(&tbl->lock);

		p->next		= tbl->parms.next;

		tbl->parms.next = p;

		list_add(&p->list, &tbl->parms.list);

		write_unlock_bh(&tbl->lock);



		neigh_parms_data_state_cleanall(p);
@@ -1501,24 +1500,15 @@ static void neigh_rcu_free_parms(struct rcu_head *head) 


void neigh_parms_release(struct neigh_table *tbl, struct neigh_parms *parms)

{

	struct neigh_parms **p;



	if (!parms || parms == &tbl->parms)

		return;

	write_lock_bh(&tbl->lock);

	for (p = &tbl->parms.next; *p; p = &(*p)->next) {

		if (*p == parms) {

			*p = parms->next;

	list_del(&parms->list);

	parms->dead = 1;

	write_unlock_bh(&tbl->lock);

	if (parms->dev)

		dev_put(parms->dev);

	call_rcu(&parms->rcu_head, neigh_rcu_free_parms);

			return;

		}

	}

	write_unlock_bh(&tbl->lock);

	neigh_dbg(1, "%s: not found\n", __func__);

}

EXPORT_SYMBOL(neigh_parms_release);
@@ -1535,6 +1525,8 @@ static void neigh_table_init_no_netlink(struct neigh_table *tbl) 
	unsigned long now = jiffies;

	unsigned long phsize;



	INIT_LIST_HEAD(&tbl->parms_list);

	list_add(&tbl->parms.list, &tbl->parms_list);

	write_pnet(&tbl->parms.net, &init_net);

	atomic_set(&tbl->parms.refcnt, 1);

	tbl->parms.reachable_time =
@@ -2154,7 +2146,9 @@ static int neightbl_dump_info(struct sk_buff *skb, struct netlink_callback *cb) 
				       NLM_F_MULTI) <= 0)

			break;



		for (nidx = 0, p = tbl->parms.next; p; p = p->next) {

		nidx = 0;

		p = list_next_entry(&tbl->parms, list);

		list_for_each_entry_from(p, &tbl->parms_list, list) {

			if (!net_eq(neigh_parms_net(p), net))

				continue;