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-rw-r--r--net/ipv4/multipath_drr.c265
1 files changed, 265 insertions, 0 deletions
diff --git a/net/ipv4/multipath_drr.c b/net/ipv4/multipath_drr.c
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+++ b/net/ipv4/multipath_drr.c
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+/*
+ * 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 struct rtable *last_selection = NULL;
+
+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_remove(struct rtable *rt)
+{
+ if (last_selection == rt)
+ last_selection = NULL;
+}
+
+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;
+
+ /* if necessary and possible utilize the old alternative */
+ if ((flp->flags & FLOWI_FLAG_MULTIPATHOLDROUTE) != 0 &&
+ last_selection != NULL) {
+ result = last_selection;
+ *rp = result;
+ return;
+ }
+
+ /* 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;
+ last_selection = result;
+}
+
+static struct ip_mp_alg_ops drr_ops = {
+ .mp_alg_select_route = drr_select_route,
+ .mp_alg_remove = drr_remove,
+};
+
+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_RR);
+ 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);
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