blob: 5249dbe7c559f90fce4671405954a415aebb3b4c (
plain)
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
|
/*
* Random policy for multipath.
*
*
* Version: $Id: multipath_random.c,v 1.1.2.3 2004/09/21 08:42:11 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/module.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>
#define MULTIPATH_MAX_CANDIDATES 40
/* interface to random number generation */
static unsigned int RANDOM_SEED = 93186752;
static inline unsigned int random(unsigned int ubound)
{
static unsigned int a = 1588635695,
q = 2,
r = 1117695901;
RANDOM_SEED = a*(RANDOM_SEED % q) - r*(RANDOM_SEED / q);
return RANDOM_SEED % ubound;
}
static void random_select_route(const struct flowi *flp,
struct rtable *first,
struct rtable **rp)
{
struct rtable *rt;
struct rtable *decision;
unsigned char candidate_count = 0;
/* count all candidate */
for (rt = rcu_dereference(first); rt;
rt = rcu_dereference(rt->u.rt_next)) {
if ((rt->u.dst.flags & DST_BALANCED) != 0 &&
multipath_comparekeys(&rt->fl, flp))
++candidate_count;
}
/* choose a random candidate */
decision = first;
if (candidate_count > 1) {
unsigned char i = 0;
unsigned char candidate_no = (unsigned char)
random(candidate_count);
/* find chosen candidate and adjust GC data for all candidates
* to ensure they stay in cache
*/
for (rt = first; rt; rt = rt->u.rt_next) {
if ((rt->u.dst.flags & DST_BALANCED) != 0 &&
multipath_comparekeys(&rt->fl, flp)) {
rt->u.dst.lastuse = jiffies;
if (i == candidate_no)
decision = rt;
if (i >= candidate_count)
break;
i++;
}
}
}
decision->u.dst.__use++;
*rp = decision;
}
static struct ip_mp_alg_ops random_ops = {
.mp_alg_select_route = random_select_route,
};
static int __init random_init(void)
{
return multipath_alg_register(&random_ops, IP_MP_ALG_RANDOM);
}
static void __exit random_exit(void)
{
multipath_alg_unregister(&random_ops, IP_MP_ALG_RANDOM);
}
module_init(random_init);
module_exit(random_exit);
MODULE_LICENSE("GPL");
|
