This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / net / ipv4 / multipath_random.c

diff --git a/net/ipv4/multipath_random.c b/net/ipv4/multipath_random.c
new file mode 100644 (file)
index 0000000..5249dbe
--- /dev/null
+++ b/net/ipv4/multipath_random.c
@@ -0,0 +1,130 @@
+/*
+ *              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");