1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
|
/*
* Device round robin policy for multipath.
*
*
* Version: $Id: multipath_drr.c,v 1.1.2.1 2004/09/16 07:42:34 elueck Exp $
*
* Authors: Einar Lueck <elueck@de.ibm.com><lkml@einar-lueck.de>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/config.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/igmp.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/mroute.h>
#include <linux/init.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/icmp.h>
#include <net/udp.h>
#include <net/raw.h>
#include <linux/notifier.h>
#include <linux/if_arp.h>
#include <linux/netfilter_ipv4.h>
#include <net/ipip.h>
#include <net/checksum.h>
#include <net/ip_mp_alg.h>
struct multipath_device {
int ifi; /* interface index of device */
atomic_t usecount;
int allocated;
};
#define MULTIPATH_MAX_DEVICECANDIDATES 10
static struct multipath_device state[MULTIPATH_MAX_DEVICECANDIDATES];
static DEFINE_SPINLOCK(state_lock);
static int inline __multipath_findslot(void)
{
int i;
for (i = 0; i < MULTIPATH_MAX_DEVICECANDIDATES; i++) {
if (state[i].allocated == 0)
return i;
}
return -1;
}
static int inline __multipath_finddev(int ifindex)
{
int i;
for (i = 0; i < MULTIPATH_MAX_DEVICECANDIDATES; i++) {
if (state[i].allocated != 0 &&
state[i].ifi == ifindex)
return i;
}
return -1;
}
static int drr_dev_event(struct notifier_block *this,
unsigned long event, void *ptr)
{
struct net_device *dev = ptr;
int devidx;
switch (event) {
case NETDEV_UNREGISTER:
case NETDEV_DOWN:
spin_lock_bh(&state_lock);
devidx = __multipath_finddev(dev->ifindex);
if (devidx != -1) {
state[devidx].allocated = 0;
state[devidx].ifi = 0;
atomic_set(&state[devidx].usecount, 0);
}
spin_unlock_bh(&state_lock);
break;
};
return NOTIFY_DONE;
}
struct notifier_block drr_dev_notifier = {
.notifier_call = drr_dev_event,
};
static void drr_safe_inc(atomic_t *usecount)
{
int n;
atomic_inc(usecount);
n = atomic_read(usecount);
if (n <= 0) {
int i;
spin_lock_bh(&state_lock);
for (i = 0; i < MULTIPATH_MAX_DEVICECANDIDATES; i++)
atomic_set(&state[i].usecount, 0);
spin_unlock_bh(&state_lock);
}
}
static void drr_select_route(const struct flowi *flp,
struct rtable *first, struct rtable **rp)
{
struct rtable *nh, *result, *cur_min;
int min_usecount = -1;
int devidx = -1;
int cur_min_devidx = -1;
/* 1. make sure all alt. nexthops have the same GC related data */
/* 2. determine the new candidate to be returned */
result = NULL;
cur_min = NULL;
for (nh = rcu_dereference(first); nh;
nh = rcu_dereference(nh->u.rt_next)) {
if ((nh->u.dst.flags & DST_BALANCED) != 0 &&
multipath_comparekeys(&nh->fl, flp)) {
int nh_ifidx = nh->u.dst.dev->ifindex;
nh->u.dst.lastuse = jiffies;
nh->u.dst.__use++;
if (result != NULL)
continue;
/* search for the output interface */
/* this is not SMP safe, only add/remove are
* SMP safe as wrong usecount updates have no big
* impact
*/
devidx = __multipath_finddev(nh_ifidx);
if (devidx == -1) {
/* add the interface to the array
* SMP safe
*/
spin_lock_bh(&state_lock);
/* due to SMP: search again */
devidx = __multipath_finddev(nh_ifidx);
if (devidx == -1) {
/* add entry for device */
devidx = __multipath_findslot();
if (devidx == -1) {
/* unlikely but possible */
continue;
}
state[devidx].allocated = 1;
state[devidx].ifi = nh_ifidx;
atomic_set(&state[devidx].usecount, 0);
min_usecount = 0;
}
spin_unlock_bh(&state_lock);
}
if (min_usecount == 0) {
/* if the device has not been used it is
* the primary target
*/
drr_safe_inc(&state[devidx].usecount);
result = nh;
} else {
int count =
atomic_read(&state[devidx].usecount);
if (min_usecount == -1 ||
count < min_usecount) {
cur_min = nh;
cur_min_devidx = devidx;
min_usecount = count;
}
}
}
}
if (!result) {
if (cur_min) {
drr_safe_inc(&state[cur_min_devidx].usecount);
result = cur_min;
} else {
result = first;
}
}
*rp = result;
}
static struct ip_mp_alg_ops drr_ops = {
.mp_alg_select_route = drr_select_route,
};
static int __init drr_init(void)
{
int err = register_netdevice_notifier(&drr_dev_notifier);
if (err)
return err;
err = multipath_alg_register(&drr_ops, IP_MP_ALG_DRR);
if (err)
goto fail;
return 0;
fail:
unregister_netdevice_notifier(&drr_dev_notifier);
return err;
}
static void __exit drr_exit(void)
{
unregister_netdevice_notifier(&drr_dev_notifier);
multipath_alg_unregister(&drr_ops, IP_MP_ALG_DRR);
}
module_init(drr_init);
module_exit(drr_exit);
|
