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Date: Sat, 6 Apr 2013 14:17:22 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 23/51] ipvs: convert rr scheduler to rcu
From: Julian Anastasov <ja@....bg>
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 <ja@....bg>
Signed-off-by: Simon Horman <horms@...ge.net.au>
---
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,
};
--
1.7.10.4
--
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