Subject: [PATCH v2] bonding: move IPv6 support into a separate kernel module

From: Brian Haley <[email-masked]>
Date: Wed, 25 Feb 2009 15:44:35 -0500

[Possible fix v2 for bonding IPv6 regression reported by Andrey Borzenkov, added 
automatic loading of bonding_ipv6]

This patch moves the IPv6 bonding code into a separate kernel module
called bonding_ipv6 if either bonding or IPv6 are built as modules.
If both are built into the kernel then this is as well.  Bonding_ipv6.ko
registers an "send_unsol_na" function pointer for the unsolicited
advertisement function to be called on a failover - the default action
is to do nothing.  The notifier callbacks are now registered in this
module and not in the base bonding module.

Also, have the IPv6 address notifier request that the bonding_ipv6
module be loaded when an IFF_MASTER device is first brought-up.
This avoids users from having to do this explicitly with modprobe.

Signed-off-by: Brian Haley <[email-masked]>
---
  Documentation/networking/bonding.txt |    3 ++
  drivers/net/bonding/Makefile         |    5 ++-
  drivers/net/bonding/bond_ipv6.c      |   13 +++++++-
  drivers/net/bonding/bond_main.c      |   52 ++++++++++++++++++++++++++++++---
  drivers/net/bonding/bonding.h        |    9 +++--
  net/ipv6/addrconf.c                  |    6 ++++++
  6 files changed, 75 insertions(+), 13 deletions(-)

diff --git a/Documentation/networking/bonding.txt 
b/Documentation/networking/bonding.txt
index 5ede747..c8b1c1f 100644
--- a/Documentation/networking/bonding.txt
+++ b/Documentation/networking/bonding.txt
@@ -603,6 +603,9 @@ num_unsol_na
  	affects only the active-backup mode.  This option was added for
  	bonding version 3.4.0.

+	In order to get this functionality, you will need to load the
+	Bonding IPv6 module with 'modprobe bonding_ipv6'.
+
  primary

  	A string (eth0, eth2, etc) specifying which slave is the
diff --git a/drivers/net/bonding/Makefile b/drivers/net/bonding/Makefile
index 6f9c6fa..d4f6338 100644
--- a/drivers/net/bonding/Makefile
+++ b/drivers/net/bonding/Makefile
@@ -6,6 +6,7 @@ obj-$(CONFIG_BONDING) += bonding.o

  bonding-objs := bond_main.o bond_3ad.o bond_alb.o bond_sysfs.o

-ipv6-$(subst m,y,$(CONFIG_IPV6)) += bond_ipv6.o
-bonding-objs += $(ipv6-y)
+# build bonding_ipv6 as module whenever either IPv6 or Bonding is a module
+obj-$(subst y,$(CONFIG_BONDING),$(CONFIG_IPV6)) += bonding_ipv6.o
+bonding_ipv6-y := bond_ipv6.o

diff --git a/drivers/net/bonding/bond_ipv6.c b/drivers/net/bonding/bond_ipv6.c
index 0d73bf5..2f10514 100644
--- a/drivers/net/bonding/bond_ipv6.c
+++ b/drivers/net/bonding/bond_ipv6.c
@@ -20,6 +20,9 @@
   *
   */

+#include <linux/module.h>
+#include <linux/init.h>
+
  #include <linux/types.h>
  #include <linux/if_vlan.h>
  #include <net/ipv6.h>
@@ -204,13 +207,19 @@ static struct notifier_block bond_inet6addr_notifier = {
  	.notifier_call = bond_inet6addr_event,
  };

-void bond_register_ipv6_notifier(void)
+static int __init bonding_ipv6_init(void)
  {
+	bond_register_ipv6_na(bond_send_unsolicited_na);
  	register_inet6addr_notifier(&bond_inet6addr_notifier);
+	return 0;
  }

-void bond_unregister_ipv6_notifier(void)
+static void __exit bonding_ipv6_exit(void)
  {
  	unregister_inet6addr_notifier(&bond_inet6addr_notifier);
+	bond_unregister_ipv6_na();
  }

+module_init(bonding_ipv6_init)
+module_exit(bonding_ipv6_exit)
+MODULE_LICENSE("GPL");
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 2c96b93..ff61add 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -149,6 +149,12 @@ static const char * const version =
  	DRV_DESCRIPTION ": v" DRV_VERSION " (" DRV_RELDATE ")\n";

  LIST_HEAD(bond_dev_list);
+EXPORT_SYMBOL(bond_dev_list);
+
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+static DEFINE_SPINLOCK(bond_v6_na_lock);
+#endif
+static void (*bond_send_unsol_na)(struct bonding *bond);

  #ifdef CONFIG_PROC_FS
  static struct proc_dir_entry *bond_proc_dir = NULL;
@@ -1201,6 +1207,8 @@ void bond_change_active_slave(struct bonding *bond, struct 
slave *new_active)
  		}

  		if (new_active) {
+			void (*send_unsol_na)(struct bonding *bond);
+
  			bond_set_slave_active_flags(new_active);

  			if (bond->params.fail_over_mac)
@@ -1211,7 +1219,11 @@ void bond_change_active_slave(struct bonding *bond, 
struct slave *new_active)
  			bond_send_gratuitous_arp(bond);

  			bond->send_unsol_na = bond->params.num_unsol_na;
-			bond_send_unsolicited_na(bond);
+			rcu_read_lock();
+			send_unsol_na = rcu_dereference(bond_send_unsol_na);
+			if (send_unsol_na)
+				send_unsol_na(bond);
+			rcu_read_unlock();

  			write_unlock_bh(&bond->curr_slave_lock);
  			read_unlock(&bond->lock);
@@ -2464,8 +2476,14 @@ void bond_mii_monitor(struct work_struct *work)
  	}

  	if (bond->send_unsol_na) {
+		void (*send_unsol_na)(struct bonding *bond);
+
  		read_lock(&bond->curr_slave_lock);
-		bond_send_unsolicited_na(bond);
+		rcu_read_lock();
+		send_unsol_na = rcu_dereference(bond_send_unsol_na);
+		if (send_unsol_na)
+			send_unsol_na(bond);
+		rcu_read_unlock();
  		read_unlock(&bond->curr_slave_lock);
  	}

@@ -3165,8 +3183,14 @@ void bond_activebackup_arp_mon(struct work_struct *work)
  	}

  	if (bond->send_unsol_na) {
+		void (*send_unsol_na)(struct bonding *bond);
+
  		read_lock(&bond->curr_slave_lock);
-		bond_send_unsolicited_na(bond);
+		rcu_read_lock();
+		send_unsol_na = rcu_dereference(bond_send_unsol_na);
+		if (send_unsol_na)
+			send_unsol_na(bond);
+		rcu_read_unlock();
  		read_unlock(&bond->curr_slave_lock);
  	}

@@ -5203,6 +5227,26 @@ out_rtnl:
  	return res;
  }

+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+void bond_register_ipv6_na(void (*send_unsol_na) (struct bonding *bond))
+{
+	spin_lock_bh(&bond_v6_na_lock);
+	rcu_assign_pointer(bond_send_unsol_na, send_unsol_na);
+	spin_unlock_bh(&bond_v6_na_lock);
+	synchronize_rcu();
+}
+EXPORT_SYMBOL_GPL(bond_register_ipv6_na);
+
+void bond_unregister_ipv6_na(void)
+{
+	spin_lock_bh(&bond_v6_na_lock);
+	rcu_assign_pointer(bond_send_unsol_na, NULL);
+	spin_unlock_bh(&bond_v6_na_lock);
+	synchronize_rcu();
+}
+EXPORT_SYMBOL(bond_unregister_ipv6_na);
+#endif
+
  static int __init bonding_init(void)
  {
  	int i;
@@ -5234,7 +5278,6 @@ static int __init bonding_init(void)

  	register_netdevice_notifier(&bond_netdev_notifier);
  	register_inetaddr_notifier(&bond_inetaddr_notifier);
-	bond_register_ipv6_notifier();

  	goto out;
  err:
@@ -5257,7 +5300,6 @@ static void __exit bonding_exit(void)
  {
  	unregister_netdevice_notifier(&bond_netdev_notifier);
  	unregister_inetaddr_notifier(&bond_inetaddr_notifier);
-	bond_unregister_ipv6_notifier();

  	bond_destroy_sysfs();

diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index ca849d2..9e5e092 100644
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -23,15 +23,13 @@
  #include "bond_3ad.h"
  #include "bond_alb.h"

-#define DRV_VERSION	"3.5.0"
-#define DRV_RELDATE	"November 4, 2008"
+#define DRV_VERSION	"3.6.0"
+#define DRV_RELDATE	"February 20, 2009"
  #define DRV_NAME	"bonding"
  #define DRV_DESCRIPTION	"Ethernet Channel Bonding Driver"

  #define BOND_MAX_ARP_TARGETS	16

-extern struct list_head bond_dev_list;
-
  #define IS_UP(dev)					   \
  	      ((((dev)->flags & IFF_UP) == IFF_UP)	&& \
  	       netif_running(dev)			&& \
@@ -360,6 +358,9 @@ extern struct rw_semaphore bonding_rwsem;
  void bond_send_unsolicited_na(struct bonding *bond);
  void bond_register_ipv6_notifier(void);
  void bond_unregister_ipv6_notifier(void);
+
+void bond_register_ipv6_na(void (*send_unsol_na) (struct bonding *bond));
+void bond_unregister_ipv6_na(void);
  #else
  static inline void bond_send_unsolicited_na(struct bonding *bond)
  {
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index f8f76d6..ec24e0e 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -59,6 +59,7 @@
  #include <linux/delay.h>
  #include <linux/notifier.h>
  #include <linux/string.h>
+#include <linux/kmod.h>

  #include <net/net_namespace.h>
  #include <net/sock.h>
@@ -2452,6 +2453,7 @@ static int addrconf_notify(struct notifier_block *this, 
unsigned long event,
  	struct inet6_dev *idev = __in6_dev_get(dev);
  	int run_pending = 0;
  	int err;
+	static int bond_ipv6 = 0;

  	switch(event) {
  	case NETDEV_REGISTER:
@@ -2519,6 +2521,10 @@ static int addrconf_notify(struct notifier_block *this, 
unsigned long event,
  			break;

  		default:
+			if ((dev->flags & IFF_MASTER) && !bond_ipv6) {
+				request_module("bonding_ipv6");
+				bond_ipv6 = 1;
+			}
  			addrconf_dev_config(dev);
  			break;
  		}
-- 
1.5.4.3