Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 265 insertions, 0 deletions

diff --git a/net/ipv4/multipath_drr.c b/net/ipv4/multipath_drr.c
new file mode 100644
index 000000000000..9349686131fc
--- /dev/null
+++ b/net/ipv4/multipath_drr.c
@@ -0,0 +1,265 @@
+/*
+ *              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);