[PATCH] remove many unneeded #includes of sched.h
[linux-2.6.git] / net / ipv4 / multipath_drr.c
1 /*
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 <asm/system.h>
16 #include <asm/uaccess.h>
17 #include <linux/types.h>
18 #include <linux/errno.h>
19 #include <linux/timer.h>
20 #include <linux/mm.h>
21 #include <linux/kernel.h>
22 #include <linux/fcntl.h>
23 #include <linux/stat.h>
24 #include <linux/socket.h>
25 #include <linux/in.h>
26 #include <linux/inet.h>
27 #include <linux/netdevice.h>
28 #include <linux/inetdevice.h>
29 #include <linux/igmp.h>
30 #include <linux/proc_fs.h>
31 #include <linux/seq_file.h>
32 #include <linux/module.h>
33 #include <linux/mroute.h>
34 #include <linux/init.h>
35 #include <net/ip.h>
36 #include <net/protocol.h>
37 #include <linux/skbuff.h>
38 #include <net/sock.h>
39 #include <net/icmp.h>
40 #include <net/udp.h>
41 #include <net/raw.h>
42 #include <linux/notifier.h>
43 #include <linux/if_arp.h>
44 #include <linux/netfilter_ipv4.h>
45 #include <net/ipip.h>
46 #include <net/checksum.h>
47 #include <net/ip_mp_alg.h>
48
49 struct multipath_device {
50         int             ifi; /* interface index of device */
51         atomic_t        usecount;
52         int             allocated;
53 };
54
55 #define MULTIPATH_MAX_DEVICECANDIDATES 10
56
57 static struct multipath_device state[MULTIPATH_MAX_DEVICECANDIDATES];
58 static DEFINE_SPINLOCK(state_lock);
59
60 static int inline __multipath_findslot(void)
61 {
62         int i;
63
64         for (i = 0; i < MULTIPATH_MAX_DEVICECANDIDATES; i++) {
65                 if (state[i].allocated == 0)
66                         return i;
67         }
68         return -1;
69 }
70
71 static int inline __multipath_finddev(int ifindex)
72 {
73         int i;
74
75         for (i = 0; i < MULTIPATH_MAX_DEVICECANDIDATES; i++) {
76                 if (state[i].allocated != 0 &&
77                     state[i].ifi == ifindex)
78                         return i;
79         }
80         return -1;
81 }
82
83 static int drr_dev_event(struct notifier_block *this,
84                          unsigned long event, void *ptr)
85 {
86         struct net_device *dev = ptr;
87         int devidx;
88
89         switch (event) {
90         case NETDEV_UNREGISTER:
91         case NETDEV_DOWN:
92                 spin_lock_bh(&state_lock);
93
94                 devidx = __multipath_finddev(dev->ifindex);
95                 if (devidx != -1) {
96                         state[devidx].allocated = 0;
97                         state[devidx].ifi = 0;
98                         atomic_set(&state[devidx].usecount, 0);
99                 }
100
101                 spin_unlock_bh(&state_lock);
102                 break;
103         };
104
105         return NOTIFY_DONE;
106 }
107
108 static struct notifier_block drr_dev_notifier = {
109         .notifier_call  = drr_dev_event,
110 };
111
112
113 static void drr_safe_inc(atomic_t *usecount)
114 {
115         int n;
116
117         atomic_inc(usecount);
118
119         n = atomic_read(usecount);
120         if (n <= 0) {
121                 int i;
122
123                 spin_lock_bh(&state_lock);
124
125                 for (i = 0; i < MULTIPATH_MAX_DEVICECANDIDATES; i++)
126                         atomic_set(&state[i].usecount, 0);
127
128                 spin_unlock_bh(&state_lock);
129         }
130 }
131
132 static void drr_select_route(const struct flowi *flp,
133                              struct rtable *first, struct rtable **rp)
134 {
135         struct rtable *nh, *result, *cur_min;
136         int min_usecount = -1;
137         int devidx = -1;
138         int cur_min_devidx = -1;
139
140         /* 1. make sure all alt. nexthops have the same GC related data */
141         /* 2. determine the new candidate to be returned */
142         result = NULL;
143         cur_min = NULL;
144         for (nh = rcu_dereference(first); nh;
145              nh = rcu_dereference(nh->u.dst.rt_next)) {
146                 if ((nh->u.dst.flags & DST_BALANCED) != 0 &&
147                     multipath_comparekeys(&nh->fl, flp)) {
148                         int nh_ifidx = nh->u.dst.dev->ifindex;
149
150                         nh->u.dst.lastuse = jiffies;
151                         nh->u.dst.__use++;
152                         if (result != NULL)
153                                 continue;
154
155                         /* search for the output interface */
156
157                         /* this is not SMP safe, only add/remove are
158                          * SMP safe as wrong usecount updates have no big
159                          * impact
160                          */
161                         devidx = __multipath_finddev(nh_ifidx);
162                         if (devidx == -1) {
163                                 /* add the interface to the array
164                                  * SMP safe
165                                  */
166                                 spin_lock_bh(&state_lock);
167
168                                 /* due to SMP: search again */
169                                 devidx = __multipath_finddev(nh_ifidx);
170                                 if (devidx == -1) {
171                                         /* add entry for device */
172                                         devidx = __multipath_findslot();
173                                         if (devidx == -1) {
174                                                 /* unlikely but possible */
175                                                 continue;
176                                         }
177
178                                         state[devidx].allocated = 1;
179                                         state[devidx].ifi = nh_ifidx;
180                                         atomic_set(&state[devidx].usecount, 0);
181                                         min_usecount = 0;
182                                 }
183
184                                 spin_unlock_bh(&state_lock);
185                         }
186
187                         if (min_usecount == 0) {
188                                 /* if the device has not been used it is
189                                  * the primary target
190                                  */
191                                 drr_safe_inc(&state[devidx].usecount);
192                                 result = nh;
193                         } else {
194                                 int count =
195                                         atomic_read(&state[devidx].usecount);
196
197                                 if (min_usecount == -1 ||
198                                     count < min_usecount) {
199                                         cur_min = nh;
200                                         cur_min_devidx = devidx;
201                                         min_usecount = count;
202                                 }
203                         }
204                 }
205         }
206
207         if (!result) {
208                 if (cur_min) {
209                         drr_safe_inc(&state[cur_min_devidx].usecount);
210                         result = cur_min;
211                 } else {
212                         result = first;
213                 }
214         }
215
216         *rp = result;
217 }
218
219 static struct ip_mp_alg_ops drr_ops = {
220         .mp_alg_select_route    =       drr_select_route,
221 };
222
223 static int __init drr_init(void)
224 {
225         int err = register_netdevice_notifier(&drr_dev_notifier);
226
227         if (err)
228                 return err;
229
230         err = multipath_alg_register(&drr_ops, IP_MP_ALG_DRR);
231         if (err)
232                 goto fail;
233
234         return 0;
235
236 fail:
237         unregister_netdevice_notifier(&drr_dev_notifier);
238         return err;
239 }
240
241 static void __exit drr_exit(void)
242 {
243         unregister_netdevice_notifier(&drr_dev_notifier);
244         multipath_alg_unregister(&drr_ops, IP_MP_ALG_DRR);
245 }
246
247 module_init(drr_init);
248 module_exit(drr_exit);
249 MODULE_LICENSE("GPL");