2 * IPVS: Round-Robin Scheduling module
4 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
5 * Peter Kese <peter.kese@ijs.si>
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
13 * Wensong Zhang : changed the ip_vs_rr_schedule to return dest
14 * Julian Anastasov : fixed the NULL pointer access bug in debugging
15 * Wensong Zhang : changed some comestics things for debugging
16 * Wensong Zhang : changed for the d-linked destination list
17 * Wensong Zhang : added the ip_vs_rr_update_svc
18 * Wensong Zhang : added any dest with weight=0 is quiesced
22 #define KMSG_COMPONENT "IPVS"
23 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
25 #include <linux/module.h>
26 #include <linux/kernel.h>
28 #include <net/ip_vs.h>
31 static int ip_vs_rr_init_svc(struct ip_vs_service
*svc
)
33 svc
->sched_data
= &svc
->destinations
;
38 static int ip_vs_rr_del_dest(struct ip_vs_service
*svc
, struct ip_vs_dest
*dest
)
42 spin_lock_bh(&svc
->sched_lock
);
43 p
= (struct list_head
*) svc
->sched_data
;
44 /* dest is already unlinked, so p->prev is not valid but
45 * p->next is valid, use it to reach previous entry.
47 if (p
== &dest
->n_list
)
48 svc
->sched_data
= p
->next
->prev
;
49 spin_unlock_bh(&svc
->sched_lock
);
55 * Round-Robin Scheduling
57 static struct ip_vs_dest
*
58 ip_vs_rr_schedule(struct ip_vs_service
*svc
, const struct sk_buff
*skb
)
61 struct ip_vs_dest
*dest
, *last
;
64 IP_VS_DBG(6, "%s(): Scheduling...\n", __func__
);
66 spin_lock_bh(&svc
->sched_lock
);
67 p
= (struct list_head
*) svc
->sched_data
;
68 last
= dest
= list_entry(p
, struct ip_vs_dest
, n_list
);
71 list_for_each_entry_continue_rcu(dest
,
74 if (!(dest
->flags
& IP_VS_DEST_F_OVERLOAD
) &&
75 atomic_read(&dest
->weight
) > 0)
82 /* Previous dest could be unlinked, do not loop forever.
83 * If we stay at head there is no need for 2nd pass.
85 } while (pass
< 2 && p
!= &svc
->destinations
);
88 spin_unlock_bh(&svc
->sched_lock
);
89 ip_vs_scheduler_err(svc
, "no destination available");
93 svc
->sched_data
= &dest
->n_list
;
94 spin_unlock_bh(&svc
->sched_lock
);
95 IP_VS_DBG_BUF(6, "RR: server %s:%u "
96 "activeconns %d refcnt %d weight %d\n",
97 IP_VS_DBG_ADDR(svc
->af
, &dest
->addr
), ntohs(dest
->port
),
98 atomic_read(&dest
->activeconns
),
99 atomic_read(&dest
->refcnt
), atomic_read(&dest
->weight
));
105 static struct ip_vs_scheduler ip_vs_rr_scheduler
= {
106 .name
= "rr", /* name */
107 .refcnt
= ATOMIC_INIT(0),
108 .module
= THIS_MODULE
,
109 .n_list
= LIST_HEAD_INIT(ip_vs_rr_scheduler
.n_list
),
110 .init_service
= ip_vs_rr_init_svc
,
112 .del_dest
= ip_vs_rr_del_dest
,
113 .schedule
= ip_vs_rr_schedule
,
116 static int __init
ip_vs_rr_init(void)
118 return register_ip_vs_scheduler(&ip_vs_rr_scheduler
);
121 static void __exit
ip_vs_rr_cleanup(void)
123 unregister_ip_vs_scheduler(&ip_vs_rr_scheduler
);
127 module_init(ip_vs_rr_init
);
128 module_exit(ip_vs_rr_cleanup
);
129 MODULE_LICENSE("GPL");