1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * IPVS: Round-Robin Scheduling module |
4 | * |
5 | * Authors: Wensong Zhang <wensong@linuxvirtualserver.org> |
6 | * Peter Kese <peter.kese@ijs.si> |
7 | * |
8 | * Fixes/Changes: |
9 | * Wensong Zhang : changed the ip_vs_rr_schedule to return dest |
10 | * Julian Anastasov : fixed the NULL pointer access bug in debugging |
11 | * Wensong Zhang : changed some comestics things for debugging |
12 | * Wensong Zhang : changed for the d-linked destination list |
13 | * Wensong Zhang : added the ip_vs_rr_update_svc |
14 | * Wensong Zhang : added any dest with weight=0 is quiesced |
15 | */ |
16 | |
17 | #define KMSG_COMPONENT "IPVS" |
18 | #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt |
19 | |
20 | #include <linux/module.h> |
21 | #include <linux/kernel.h> |
22 | |
23 | #include <net/ip_vs.h> |
24 | |
25 | |
26 | static int ip_vs_rr_init_svc(struct ip_vs_service *svc) |
27 | { |
28 | svc->sched_data = &svc->destinations; |
29 | return 0; |
30 | } |
31 | |
32 | |
33 | static int ip_vs_rr_del_dest(struct ip_vs_service *svc, struct ip_vs_dest *dest) |
34 | { |
35 | struct list_head *p; |
36 | |
37 | spin_lock_bh(lock: &svc->sched_lock); |
38 | p = (struct list_head *) svc->sched_data; |
39 | /* dest is already unlinked, so p->prev is not valid but |
40 | * p->next is valid, use it to reach previous entry. |
41 | */ |
42 | if (p == &dest->n_list) |
43 | svc->sched_data = p->next->prev; |
44 | spin_unlock_bh(lock: &svc->sched_lock); |
45 | return 0; |
46 | } |
47 | |
48 | |
49 | /* |
50 | * Round-Robin Scheduling |
51 | */ |
52 | static struct ip_vs_dest * |
53 | ip_vs_rr_schedule(struct ip_vs_service *svc, const struct sk_buff *skb, |
54 | struct ip_vs_iphdr *iph) |
55 | { |
56 | struct list_head *p; |
57 | struct ip_vs_dest *dest, *last; |
58 | int pass = 0; |
59 | |
60 | IP_VS_DBG(6, "%s(): Scheduling...\n" , __func__); |
61 | |
62 | spin_lock_bh(lock: &svc->sched_lock); |
63 | p = (struct list_head *) svc->sched_data; |
64 | last = dest = list_entry(p, struct ip_vs_dest, n_list); |
65 | |
66 | do { |
67 | list_for_each_entry_continue_rcu(dest, |
68 | &svc->destinations, |
69 | n_list) { |
70 | if (!(dest->flags & IP_VS_DEST_F_OVERLOAD) && |
71 | atomic_read(v: &dest->weight) > 0) |
72 | /* HIT */ |
73 | goto out; |
74 | if (dest == last) |
75 | goto stop; |
76 | } |
77 | pass++; |
78 | /* Previous dest could be unlinked, do not loop forever. |
79 | * If we stay at head there is no need for 2nd pass. |
80 | */ |
81 | } while (pass < 2 && p != &svc->destinations); |
82 | |
83 | stop: |
84 | spin_unlock_bh(lock: &svc->sched_lock); |
85 | ip_vs_scheduler_err(svc, msg: "no destination available" ); |
86 | return NULL; |
87 | |
88 | out: |
89 | svc->sched_data = &dest->n_list; |
90 | spin_unlock_bh(lock: &svc->sched_lock); |
91 | IP_VS_DBG_BUF(6, "RR: server %s:%u " |
92 | "activeconns %d refcnt %d weight %d\n" , |
93 | IP_VS_DBG_ADDR(dest->af, &dest->addr), ntohs(dest->port), |
94 | atomic_read(&dest->activeconns), |
95 | refcount_read(&dest->refcnt), atomic_read(&dest->weight)); |
96 | |
97 | return dest; |
98 | } |
99 | |
100 | |
101 | static struct ip_vs_scheduler ip_vs_rr_scheduler = { |
102 | .name = "rr" , /* name */ |
103 | .refcnt = ATOMIC_INIT(0), |
104 | .module = THIS_MODULE, |
105 | .n_list = LIST_HEAD_INIT(ip_vs_rr_scheduler.n_list), |
106 | .init_service = ip_vs_rr_init_svc, |
107 | .add_dest = NULL, |
108 | .del_dest = ip_vs_rr_del_dest, |
109 | .schedule = ip_vs_rr_schedule, |
110 | }; |
111 | |
112 | static int __init ip_vs_rr_init(void) |
113 | { |
114 | return register_ip_vs_scheduler(scheduler: &ip_vs_rr_scheduler); |
115 | } |
116 | |
117 | static void __exit ip_vs_rr_cleanup(void) |
118 | { |
119 | unregister_ip_vs_scheduler(scheduler: &ip_vs_rr_scheduler); |
120 | synchronize_rcu(); |
121 | } |
122 | |
123 | module_init(ip_vs_rr_init); |
124 | module_exit(ip_vs_rr_cleanup); |
125 | MODULE_DESCRIPTION("ipvs round-robin scheduler" ); |
126 | MODULE_LICENSE("GPL" ); |
127 | |