blob: db67373f9b348669de5045ba39c558105c7b1219 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Device round robin policy for multipath.
3 *
4 *
5 * Version: $Id: multipath_drr.c,v 1.1.2.1 2004/09/16 07:42:34 elueck Exp $
6 *
7 * Authors: Einar Lueck <elueck@de.ibm.com><lkml@einar-lueck.de>
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version
12 * 2 of the License, or (at your option) any later version.
13 */
14
15#include <linux/config.h>
16#include <asm/system.h>
17#include <asm/uaccess.h>
18#include <linux/types.h>
19#include <linux/sched.h>
20#include <linux/errno.h>
21#include <linux/timer.h>
22#include <linux/mm.h>
23#include <linux/kernel.h>
24#include <linux/fcntl.h>
25#include <linux/stat.h>
26#include <linux/socket.h>
27#include <linux/in.h>
28#include <linux/inet.h>
29#include <linux/netdevice.h>
30#include <linux/inetdevice.h>
31#include <linux/igmp.h>
32#include <linux/proc_fs.h>
33#include <linux/seq_file.h>
Randy Dunlap6efd8452005-06-13 14:29:06 -070034#include <linux/module.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#include <linux/mroute.h>
36#include <linux/init.h>
37#include <net/ip.h>
38#include <net/protocol.h>
39#include <linux/skbuff.h>
40#include <net/sock.h>
41#include <net/icmp.h>
42#include <net/udp.h>
43#include <net/raw.h>
44#include <linux/notifier.h>
45#include <linux/if_arp.h>
46#include <linux/netfilter_ipv4.h>
47#include <net/ipip.h>
48#include <net/checksum.h>
49#include <net/ip_mp_alg.h>
50
51struct multipath_device {
52 int ifi; /* interface index of device */
53 atomic_t usecount;
54 int allocated;
55};
56
57#define MULTIPATH_MAX_DEVICECANDIDATES 10
58
59static struct multipath_device state[MULTIPATH_MAX_DEVICECANDIDATES];
60static DEFINE_SPINLOCK(state_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070061
62static int inline __multipath_findslot(void)
63{
64 int i;
65
66 for (i = 0; i < MULTIPATH_MAX_DEVICECANDIDATES; i++) {
67 if (state[i].allocated == 0)
68 return i;
69 }
70 return -1;
71}
72
73static int inline __multipath_finddev(int ifindex)
74{
75 int i;
76
77 for (i = 0; i < MULTIPATH_MAX_DEVICECANDIDATES; i++) {
78 if (state[i].allocated != 0 &&
79 state[i].ifi == ifindex)
80 return i;
81 }
82 return -1;
83}
84
85static int drr_dev_event(struct notifier_block *this,
86 unsigned long event, void *ptr)
87{
88 struct net_device *dev = ptr;
89 int devidx;
90
91 switch (event) {
92 case NETDEV_UNREGISTER:
93 case NETDEV_DOWN:
94 spin_lock_bh(&state_lock);
95
96 devidx = __multipath_finddev(dev->ifindex);
97 if (devidx != -1) {
98 state[devidx].allocated = 0;
99 state[devidx].ifi = 0;
100 atomic_set(&state[devidx].usecount, 0);
101 }
102
103 spin_unlock_bh(&state_lock);
104 break;
105 };
106
107 return NOTIFY_DONE;
108}
109
Adrian Bunk0742fd52005-08-09 19:35:47 -0700110static struct notifier_block drr_dev_notifier = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 .notifier_call = drr_dev_event,
112};
113
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114
115static void drr_safe_inc(atomic_t *usecount)
116{
117 int n;
118
119 atomic_inc(usecount);
120
121 n = atomic_read(usecount);
122 if (n <= 0) {
123 int i;
124
125 spin_lock_bh(&state_lock);
126
127 for (i = 0; i < MULTIPATH_MAX_DEVICECANDIDATES; i++)
128 atomic_set(&state[i].usecount, 0);
129
130 spin_unlock_bh(&state_lock);
131 }
132}
133
134static void drr_select_route(const struct flowi *flp,
135 struct rtable *first, struct rtable **rp)
136{
137 struct rtable *nh, *result, *cur_min;
138 int min_usecount = -1;
139 int devidx = -1;
140 int cur_min_devidx = -1;
141
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 /* 1. make sure all alt. nexthops have the same GC related data */
143 /* 2. determine the new candidate to be returned */
144 result = NULL;
145 cur_min = NULL;
146 for (nh = rcu_dereference(first); nh;
147 nh = rcu_dereference(nh->u.rt_next)) {
148 if ((nh->u.dst.flags & DST_BALANCED) != 0 &&
149 multipath_comparekeys(&nh->fl, flp)) {
150 int nh_ifidx = nh->u.dst.dev->ifindex;
151
152 nh->u.dst.lastuse = jiffies;
153 nh->u.dst.__use++;
154 if (result != NULL)
155 continue;
156
157 /* search for the output interface */
158
159 /* this is not SMP safe, only add/remove are
160 * SMP safe as wrong usecount updates have no big
161 * impact
162 */
163 devidx = __multipath_finddev(nh_ifidx);
164 if (devidx == -1) {
165 /* add the interface to the array
166 * SMP safe
167 */
168 spin_lock_bh(&state_lock);
169
170 /* due to SMP: search again */
171 devidx = __multipath_finddev(nh_ifidx);
172 if (devidx == -1) {
173 /* add entry for device */
174 devidx = __multipath_findslot();
175 if (devidx == -1) {
176 /* unlikely but possible */
177 continue;
178 }
179
180 state[devidx].allocated = 1;
181 state[devidx].ifi = nh_ifidx;
182 atomic_set(&state[devidx].usecount, 0);
183 min_usecount = 0;
184 }
185
186 spin_unlock_bh(&state_lock);
187 }
188
189 if (min_usecount == 0) {
190 /* if the device has not been used it is
191 * the primary target
192 */
193 drr_safe_inc(&state[devidx].usecount);
194 result = nh;
195 } else {
196 int count =
197 atomic_read(&state[devidx].usecount);
198
199 if (min_usecount == -1 ||
200 count < min_usecount) {
201 cur_min = nh;
202 cur_min_devidx = devidx;
203 min_usecount = count;
204 }
205 }
206 }
207 }
208
209 if (!result) {
210 if (cur_min) {
211 drr_safe_inc(&state[cur_min_devidx].usecount);
212 result = cur_min;
213 } else {
214 result = first;
215 }
216 }
217
218 *rp = result;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219}
220
221static struct ip_mp_alg_ops drr_ops = {
222 .mp_alg_select_route = drr_select_route,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223};
224
225static int __init drr_init(void)
226{
227 int err = register_netdevice_notifier(&drr_dev_notifier);
228
229 if (err)
230 return err;
231
Pravin B. Shelar37e20a62005-05-29 20:26:44 -0700232 err = multipath_alg_register(&drr_ops, IP_MP_ALG_DRR);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 if (err)
234 goto fail;
235
236 return 0;
237
238fail:
239 unregister_netdevice_notifier(&drr_dev_notifier);
240 return err;
241}
242
243static void __exit drr_exit(void)
244{
245 unregister_netdevice_notifier(&drr_dev_notifier);
246 multipath_alg_unregister(&drr_ops, IP_MP_ALG_DRR);
247}
248
249module_init(drr_init);
250module_exit(drr_exit);
Randy Dunlap6efd8452005-06-13 14:29:06 -0700251MODULE_LICENSE("GPL");