Name: notifier_unregister should return void
Author: Rusty Russell
Status: Tested on 2.5.66-bk2

Noone uses the return value of notifier_chain_unregister and its
children: make it BUG() when unregistering a non-existent notifier,
and return void.

Index: linux-2.6.10-rc2-bk9-Misc/kernel/sys.c
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/kernel/sys.c	2004-11-16 15:30:10.000000000 +1100
+++ linux-2.6.10-rc2-bk9-Misc/kernel/sys.c	2004-11-27 14:54:38.197307856 +1100
@@ -123,11 +123,9 @@
  *	@n: New entry in notifier chain
  *
  *	Removes a notifier from a notifier chain.
- *
- *	Returns zero on success, or %-ENOENT on failure.
  */
  
-int notifier_chain_unregister(struct notifier_block **nl, struct notifier_block *n)
+void notifier_chain_unregister(struct notifier_block **nl, struct notifier_block *n)
 {
 	write_lock(&notifier_lock);
 	while((*nl)!=NULL)
@@ -136,12 +134,12 @@
 		{
 			*nl=n->next;
 			write_unlock(&notifier_lock);
-			return 0;
+			return;
 		}
 		nl=&((*nl)->next);
 	}
 	write_unlock(&notifier_lock);
-	return -ENOENT;
+	BUG();
 }
 
 EXPORT_SYMBOL(notifier_chain_unregister);
@@ -205,13 +203,11 @@
  *
  *	Unregisters a previously registered reboot
  *	notifier function.
- *
- *	Returns zero on success, or %-ENOENT on failure.
  */
  
-int unregister_reboot_notifier(struct notifier_block * nb)
+void unregister_reboot_notifier(struct notifier_block * nb)
 {
-	return notifier_chain_unregister(&reboot_notifier_list, nb);
+	notifier_chain_unregister(&reboot_notifier_list, nb);
 }
 
 EXPORT_SYMBOL(unregister_reboot_notifier);
Index: linux-2.6.10-rc2-bk9-Misc/net/netlink/af_netlink.c
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/net/netlink/af_netlink.c	2004-11-26 11:37:08.000000000 +1100
+++ linux-2.6.10-rc2-bk9-Misc/net/netlink/af_netlink.c	2004-11-27 14:54:38.203306944 +1100
@@ -1407,9 +1407,9 @@
 	return notifier_chain_register(&netlink_chain, nb);
 }
 
-int netlink_unregister_notifier(struct notifier_block *nb)
+void netlink_unregister_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_unregister(&netlink_chain, nb);
+	notifier_chain_unregister(&netlink_chain, nb);
 }
                 
 static struct proto_ops netlink_ops = {
Index: linux-2.6.10-rc2-bk9-Misc/include/linux/profile.h
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/include/linux/profile.h	2004-11-16 15:30:07.000000000 +1100
+++ linux-2.6.10-rc2-bk9-Misc/include/linux/profile.h	2004-11-27 14:56:32.173980768 +1100
@@ -48,10 +48,10 @@
 void profile_munmap(unsigned long addr);
 
 int task_handoff_register(struct notifier_block * n);
-int task_handoff_unregister(struct notifier_block * n);
+void task_handoff_unregister(struct notifier_block * n);
 
 int profile_event_register(enum profile_type, struct notifier_block * n);
-int profile_event_unregister(enum profile_type, struct notifier_block * n);
+void profile_event_unregister(enum profile_type, struct notifier_block * n);
 
 int register_timer_hook(int (*hook)(struct pt_regs *));
 void unregister_timer_hook(int (*hook)(struct pt_regs *));
@@ -68,9 +68,9 @@
 	return -ENOSYS;
 }
 
-static inline int task_handoff_unregister(struct notifier_block * n)
+static inline void task_handoff_unregister(struct notifier_block * n)
 {
-	return -ENOSYS;
+	return;
 }
 
 static inline int profile_event_register(enum profile_type t, struct notifier_block * n)
@@ -78,9 +78,8 @@
 	return -ENOSYS;
 }
 
-static inline int profile_event_unregister(enum profile_type t, struct notifier_block * n)
+static inline void profile_event_unregister(enum profile_type t, struct notifier_block * n)
 {
-	return -ENOSYS;
 }
 
 #define profile_task_exit(a) do { } while (0)
Index: linux-2.6.10-rc2-bk9-Misc/include/linux/netlink.h
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/include/linux/netlink.h	2004-11-16 15:30:07.000000000 +1100
+++ linux-2.6.10-rc2-bk9-Misc/include/linux/netlink.h	2004-11-27 14:54:38.193308464 +1100
@@ -126,7 +126,7 @@
 			     __u32 group, int allocation);
 extern void netlink_set_err(struct sock *ssk, __u32 pid, __u32 group, int code);
 extern int netlink_register_notifier(struct notifier_block *nb);
-extern int netlink_unregister_notifier(struct notifier_block *nb);
+extern void netlink_unregister_notifier(struct notifier_block *nb);
 
 /* finegrained unicast helpers: */
 struct sock *netlink_getsockbypid(struct sock *ssk, u32 pid);
Index: linux-2.6.10-rc2-bk9-Misc/kernel/profile.c
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/kernel/profile.c	2004-11-16 15:30:10.000000000 +1100
+++ linux-2.6.10-rc2-bk9-Misc/kernel/profile.c	2004-11-27 14:56:32.200976664 +1100
@@ -121,14 +121,11 @@
 	return err;
 }
 
-int task_handoff_unregister(struct notifier_block * n)
+void task_handoff_unregister(struct notifier_block * n)
 {
-	int err = -EINVAL;
-
 	write_lock(&handoff_lock);
-	err = notifier_chain_unregister(&task_free_notifier, n);
+	notifier_chain_unregister(&task_free_notifier, n);
 	write_unlock(&handoff_lock);
-	return err;
 }
 
 int profile_event_register(enum profile_type type, struct notifier_block * n)
@@ -152,23 +149,20 @@
 }
 
  
-int profile_event_unregister(enum profile_type type, struct notifier_block * n)
+void profile_event_unregister(enum profile_type type, struct notifier_block * n)
 {
-	int err = -EINVAL;
- 
 	down_write(&profile_rwsem);
  
 	switch (type) {
 		case PROFILE_TASK_EXIT:
-			err = notifier_chain_unregister(&task_exit_notifier, n);
+			notifier_chain_unregister(&task_exit_notifier, n);
 			break;
 		case PROFILE_MUNMAP:
-			err = notifier_chain_unregister(&munmap_notifier, n);
+			notifier_chain_unregister(&munmap_notifier, n);
 			break;
 	}
 
 	up_write(&profile_rwsem);
-	return err;
 }
 
 int register_timer_hook(int (*hook)(struct pt_regs *))
Index: linux-2.6.10-rc2-bk9-Misc/include/linux/reboot.h
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/include/linux/reboot.h	2004-06-17 08:49:37.000000000 +1000
+++ linux-2.6.10-rc2-bk9-Misc/include/linux/reboot.h	2004-11-27 14:54:38.194308312 +1100
@@ -40,7 +40,7 @@
 #include <linux/notifier.h>
 
 extern int register_reboot_notifier(struct notifier_block *);
-extern int unregister_reboot_notifier(struct notifier_block *);
+extern void unregister_reboot_notifier(struct notifier_block *);
 
 
 /*
Index: linux-2.6.10-rc2-bk9-Misc/include/net/addrconf.h
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/include/net/addrconf.h	2004-11-16 15:30:08.000000000 +1100
+++ linux-2.6.10-rc2-bk9-Misc/include/net/addrconf.h	2004-11-27 14:54:38.195308160 +1100
@@ -118,7 +118,7 @@
 
 /* Device notifier */
 extern int register_inet6addr_notifier(struct notifier_block *nb);
-extern int unregister_inet6addr_notifier(struct notifier_block *nb);
+extern void unregister_inet6addr_notifier(struct notifier_block *nb);
 
 static inline struct inet6_dev *
 __in6_dev_get(struct net_device *dev)
Index: linux-2.6.10-rc2-bk9-Misc/include/linux/notifier.h
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/include/linux/notifier.h	2004-11-16 15:30:07.000000000 +1100
+++ linux-2.6.10-rc2-bk9-Misc/include/linux/notifier.h	2004-11-27 14:54:38.194308312 +1100
@@ -22,7 +22,7 @@
 #ifdef __KERNEL__
 
 extern int notifier_chain_register(struct notifier_block **list, struct notifier_block *n);
-extern int notifier_chain_unregister(struct notifier_block **nl, struct notifier_block *n);
+extern void notifier_chain_unregister(struct notifier_block **nl, struct notifier_block *n);
 extern int notifier_call_chain(struct notifier_block **n, unsigned long val, void *v);
 
 #define NOTIFY_DONE		0x0000		/* Don't care */
Index: linux-2.6.10-rc2-bk9-Misc/include/linux/inetdevice.h
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/include/linux/inetdevice.h	2004-11-16 15:30:07.000000000 +1100
+++ linux-2.6.10-rc2-bk9-Misc/include/linux/inetdevice.h	2004-11-27 14:54:38.192308616 +1100
@@ -99,7 +99,7 @@
 };
 
 extern int register_inetaddr_notifier(struct notifier_block *nb);
-extern int unregister_inetaddr_notifier(struct notifier_block *nb);
+extern void unregister_inetaddr_notifier(struct notifier_block *nb);
 
 extern struct net_device 	*ip_dev_find(u32 addr);
 extern int		inet_addr_onlink(struct in_device *in_dev, u32 a, u32 b);
Index: linux-2.6.10-rc2-bk9-Misc/net/ipv4/devinet.c
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/net/ipv4/devinet.c	2004-11-16 15:30:12.000000000 +1100
+++ linux-2.6.10-rc2-bk9-Misc/net/ipv4/devinet.c	2004-11-27 14:54:38.201307248 +1100
@@ -900,9 +900,9 @@
 	return notifier_chain_register(&inetaddr_chain, nb);
 }
 
-int unregister_inetaddr_notifier(struct notifier_block *nb)
+void unregister_inetaddr_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_unregister(&inetaddr_chain, nb);
+	notifier_chain_unregister(&inetaddr_chain, nb);
 }
 
 /* Rename ifa_labels for a device name change. Make some effort to preserve existing
Index: linux-2.6.10-rc2-bk9-Misc/include/net/bluetooth/hci_core.h
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/include/net/bluetooth/hci_core.h	2004-11-16 15:30:08.000000000 +1100
+++ linux-2.6.10-rc2-bk9-Misc/include/net/bluetooth/hci_core.h	2004-11-27 14:54:38.195308160 +1100
@@ -539,7 +539,7 @@
 int hci_unregister_cb(struct hci_cb *hcb);
 
 int hci_register_notifier(struct notifier_block *nb);
-int hci_unregister_notifier(struct notifier_block *nb);
+void hci_unregister_notifier(struct notifier_block *nb);
 
 int hci_send_cmd(struct hci_dev *hdev, __u16 ogf, __u16 ocf, __u32 plen, void *param);
 int hci_send_acl(struct hci_conn *conn, struct sk_buff *skb, __u16 flags);
Index: linux-2.6.10-rc2-bk9-Misc/net/ipv6/addrconf.c
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/net/ipv6/addrconf.c	2004-11-26 11:37:08.000000000 +1100
+++ linux-2.6.10-rc2-bk9-Misc/net/ipv6/addrconf.c	2004-11-27 14:54:38.202307096 +1100
@@ -3376,9 +3376,9 @@
         return notifier_chain_register(&inet6addr_chain, nb);
 }
 
-int unregister_inet6addr_notifier(struct notifier_block *nb)
+void unregister_inet6addr_notifier(struct notifier_block *nb)
 {
-        return notifier_chain_unregister(&inet6addr_chain,nb);
+	notifier_chain_unregister(&inet6addr_chain,nb);
 }
 
 /*
Index: linux-2.6.10-rc2-bk9-Misc/net/core/dev.c
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/net/core/dev.c	2004-11-26 11:37:07.000000000 +1100
+++ linux-2.6.10-rc2-bk9-Misc/net/core/dev.c	2004-11-27 14:54:38.200307400 +1100
@@ -978,13 +978,12 @@
  *
  *	Unregister a notifier previously registered by
  *	register_netdevice_notifier(). The notifier is unlinked into the
- *	kernel structures and may then be reused. A negative errno code
- *	is returned on a failure.
+ *	kernel structures and may then be reused.
  */
 
-int unregister_netdevice_notifier(struct notifier_block *nb)
+void unregister_netdevice_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_unregister(&netdev_chain, nb);
+	notifier_chain_unregister(&netdev_chain, nb);
 }
 
 /**
Index: linux-2.6.10-rc2-bk9-Misc/net/bluetooth/hci_core.c
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/net/bluetooth/hci_core.c	2004-11-16 15:30:11.000000000 +1100
+++ linux-2.6.10-rc2-bk9-Misc/net/bluetooth/hci_core.c	2004-11-27 14:54:38.198307704 +1100
@@ -83,9 +83,9 @@
 	return notifier_chain_register(&hci_notifier, nb);
 }
 
-int hci_unregister_notifier(struct notifier_block *nb)
+void hci_unregister_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_unregister(&hci_notifier, nb);
+	notifier_chain_unregister(&hci_notifier, nb);
 }
 
 void hci_notify(struct hci_dev *hdev, int event)
Index: linux-2.6.10-rc2-bk9-Misc/include/linux/cpufreq.h
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/include/linux/cpufreq.h	2004-11-16 15:30:06.000000000 +1100
+++ linux-2.6.10-rc2-bk9-Misc/include/linux/cpufreq.h	2004-11-27 14:54:38.192308616 +1100
@@ -32,7 +32,7 @@
  *********************************************************************/
 
 int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list);
-int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list);
+void cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list);
 
 #define CPUFREQ_TRANSITION_NOTIFIER	(0)
 #define CPUFREQ_POLICY_NOTIFIER		(1)
Index: linux-2.6.10-rc2-bk9-Misc/include/linux/netdevice.h
===================================================================
--- linux-2.6.10-rc2-bk9-Misc.orig/include/linux/netdevice.h	2004-11-26 11:37:06.000000000 +1100
+++ linux-2.6.10-rc2-bk9-Misc/include/linux/netdevice.h	2004-11-27 14:54:38.193308464 +1100
@@ -544,7 +544,7 @@
 extern void		free_netdev(struct net_device *dev);
 extern void		synchronize_net(void);
 extern int 		register_netdevice_notifier(struct notifier_block *nb);
-extern int		unregister_netdevice_notifier(struct notifier_block *nb);
+extern void		unregister_netdevice_notifier(struct notifier_block *nb);
 extern int		call_netdevice_notifiers(unsigned long val, void *v);
 extern struct net_device	*dev_get_by_index(int ifindex);
 extern struct net_device	*__dev_get_by_index(int ifindex);