1 files changed, 125 insertions, 0 deletions
diff --git a/net/netfilter/ipvs/ip_vs_rr.c b/net/netfilter/ipvs/ip_vs_rr.c
new file mode 100644
index 000000000..38495c6f6
--- /dev/null
+++ b/net/netfilter/ipvs/ip_vs_rr.c
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * IPVS:        Round-Robin Scheduling module
+ *
+ * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
+ *              Peter Kese <peter.kese@ijs.si>
+ *
+ * Fixes/Changes:
+ *     Wensong Zhang            :     changed the ip_vs_rr_schedule to return dest
+ *     Julian Anastasov         :     fixed the NULL pointer access bug in debugging
+ *     Wensong Zhang            :     changed some comestics things for debugging
+ *     Wensong Zhang            :     changed for the d-linked destination list
+ *     Wensong Zhang            :     added the ip_vs_rr_update_svc
+ *     Wensong Zhang            :     added any dest with weight=0 is quiesced
+ */
+
+#define KMSG_COMPONENT "IPVS"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+#include <net/ip_vs.h>
+
+
+static int ip_vs_rr_init_svc(struct ip_vs_service *svc)
+{
+	svc->sched_data = &svc->destinations;
+	return 0;
+}
+
+
+static int ip_vs_rr_del_dest(struct ip_vs_service *svc, struct ip_vs_dest *dest)
+{
+	struct list_head *p;
+
+	spin_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;
+	spin_unlock_bh(&svc->sched_lock);
+	return 0;
+}
+
+
+/*
+ * Round-Robin Scheduling
+ */
+static struct ip_vs_dest *
+ip_vs_rr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb,
+		  struct ip_vs_iphdr *iph)
+{
+	struct list_head *p;
+	struct ip_vs_dest *dest, *last;
+	int pass = 0;
+
+	IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
+
+	spin_lock_bh(&svc->sched_lock);
+	p = (struct list_head *) svc->sched_data;
+	last = dest = list_entry(p, 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;
+			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:
+	spin_unlock_bh(&svc->sched_lock);
+	ip_vs_scheduler_err(svc, "no destination available");
+	return NULL;
+
+  out:
+	svc->sched_data = &dest->n_list;
+	spin_unlock_bh(&svc->sched_lock);
+	IP_VS_DBG_BUF(6, "RR: server %s:%u "
+		      "activeconns %d refcnt %d weight %d\n",
+		      IP_VS_DBG_ADDR(dest->af, &dest->addr), ntohs(dest->port),
+		      atomic_read(&dest->activeconns),
+		      refcount_read(&dest->refcnt), atomic_read(&dest->weight));
+
+	return dest;
+}
+
+
+static struct ip_vs_scheduler ip_vs_rr_scheduler = {
+	.name =			"rr",			/* name */
+	.refcnt =		ATOMIC_INIT(0),
+	.module =		THIS_MODULE,
+	.n_list =		LIST_HEAD_INIT(ip_vs_rr_scheduler.n_list),
+	.init_service =		ip_vs_rr_init_svc,
+	.add_dest =		NULL,
+	.del_dest =		ip_vs_rr_del_dest,
+	.schedule =		ip_vs_rr_schedule,
+};
+
+static int __init ip_vs_rr_init(void)
+{
+	return register_ip_vs_scheduler(&ip_vs_rr_scheduler);
+}
+
+static void __exit ip_vs_rr_cleanup(void)
+{
+	unregister_ip_vs_scheduler(&ip_vs_rr_scheduler);
+	synchronize_rcu();
+}
+
+module_init(ip_vs_rr_init);
+module_exit(ip_vs_rr_cleanup);
+MODULE_LICENSE("GPL");