From c0d0c0a1c0d35b76f3859b69110f614056d845fe Mon Sep 17 00:00:00 2001 From: Julian Anastasov Date: Fri, 22 Mar 2013 11:46:44 +0200 Subject: [PATCH] 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: Julian Anastasov Signed-off-by: Simon Horman --- net/netfilter/ipvs/ip_vs_rr.c | 55 +++++++++++++++++++++++++++---------------- 1 file changed, 35 insertions(+), 20 deletions(-) diff --git a/net/netfilter/ipvs/ip_vs_rr.c b/net/netfilter/ipvs/ip_vs_rr.c index c49b388..3942890 100644 --- a/net/netfilter/ipvs/ip_vs_rr.c +++ b/net/netfilter/ipvs/ip_vs_rr.c @@ -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; + p = (struct list_head *) svc->sched_data; + last = dest = list_entry(p, struct ip_vs_dest, n_list); + do { - /* skip list head */ - if (q == &svc->destinations) { - q = q->next; - continue; + 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; + 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); - dest = list_entry(q, struct ip_vs_dest, n_list); - if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && - atomic_read(&dest->weight) > 0) - /* HIT */ - goto out; - q = q->next; - } while (q != p); +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, }; -- 2.7.4