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Commit c0d0c0a1 authored by Julian Anastasov's avatar Julian Anastasov Committed by Pablo Neira Ayuso
Browse files

ipvs: convert rr scheduler to rcu 



The schedule method now needs _rcu list-traversal
primitive for svc->destinations. As the previous entry
could be unlinked, limit the list traversals to 2 when
lookup started from previous entry.

Signed-off-by: default avatarJulian Anastasov <ja@ssi.bg>
Signed-off-by: default avatarSimon Horman <horms@verge.net.au>
parent f92ea8f0

net/netfilter/ipvs/ip_vs_rr.c

+35 −20
Original line number Diff line number Diff line
@@ -35,9 +35,18 @@ static int ip_vs_rr_init_svc(struct ip_vs_service *svc) 
}





static int ip_vs_rr_update_svc(struct ip_vs_service *svc)

static int ip_vs_rr_del_dest(struct ip_vs_service *svc, struct ip_vs_dest *dest)

{

	svc->sched_data = &svc->destinations;

	struct list_head *p;



	write_lock_bh(&svc->sched_lock);

	p = (struct list_head *) svc->sched_data;

	/* dest is already unlinked, so p->prev is not valid but

	 * p->next is valid, use it to reach previous entry.

	 */

	if (p == &dest->n_list)

		svc->sched_data = p->next->prev;

	write_unlock_bh(&svc->sched_lock);

	return 0;

}
@@ -48,35 +57,40 @@ static int ip_vs_rr_update_svc(struct ip_vs_service *svc) 
static struct ip_vs_dest *

ip_vs_rr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)

{

	struct list_head *p, *q;

	struct ip_vs_dest *dest;

	struct list_head *p;

	struct ip_vs_dest *dest, *last;

	int pass = 0;



	IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);



	write_lock(&svc->sched_lock);

	p = (struct list_head *) svc->sched_data;

	p = p->next;

	q = p;

	do {

		/* skip list head */

		if (q == &svc->destinations) {

			q = q->next;

			continue;

		}

	last = dest = list_entry(p, struct ip_vs_dest, n_list);



		dest = list_entry(q, struct ip_vs_dest, n_list);

	do {

		list_for_each_entry_continue_rcu(dest,

						 &svc->destinations,

						 n_list) {

			if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) &&

			    atomic_read(&dest->weight) > 0)

				/* HIT */

				goto out;

		q = q->next;

	} while (q != p);

			if (dest == last)

				goto stop;

		}

		pass++;

		/* Previous dest could be unlinked, do not loop forever.

		 * If we stay at head there is no need for 2nd pass.

		 */

	} while (pass < 2 && p != &svc->destinations);



stop:

	write_unlock(&svc->sched_lock);

	ip_vs_scheduler_err(svc, "no destination available");

	return NULL;



  out:

	svc->sched_data = q;

	svc->sched_data = &dest->n_list;

	write_unlock(&svc->sched_lock);

	IP_VS_DBG_BUF(6, "RR: server %s:%u "

		      "activeconns %d refcnt %d weight %d\n",
@@ -94,7 +108,8 @@ static struct ip_vs_scheduler ip_vs_rr_scheduler = { 
	.module =		THIS_MODULE,

	.n_list =		LIST_HEAD_INIT(ip_vs_rr_scheduler.n_list),

	.init_service =		ip_vs_rr_init_svc,

	.update_service =	ip_vs_rr_update_svc,

	.add_dest =		NULL,

	.del_dest =		ip_vs_rr_del_dest,

	.schedule =		ip_vs_rr_schedule,

};