[PATCH] Notifier chain update: API changes

The kernel's implementation of notifier chains is unsafe.  There is no
protection against entries being added to or removed from a chain while the
chain is in use.  The issues were discussed in this thread:

    http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2

We noticed that notifier chains in the kernel fall into two basic usage
classes:

	"Blocking" chains are always called from a process context
	and the callout routines are allowed to sleep;

	"Atomic" chains can be called from an atomic context and
	the callout routines are not allowed to sleep.

We decided to codify this distinction and make it part of the API.  Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name).  New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain.  The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.

With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed.  For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections.  (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)

There are some limitations, which should not be too hard to live with.  For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem.  Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain.  (This did happen in a couple of places and the code
had to be changed to avoid it.)

Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization.  Instead we use RCU.  The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.

Here is the list of chains that we adjusted and their classifications.  None
of them use the raw API, so for the moment it is only a placeholder.

  ATOMIC CHAINS
  -------------
arch/i386/kernel/traps.c:		i386die_chain
arch/ia64/kernel/traps.c:		ia64die_chain
arch/powerpc/kernel/traps.c:		powerpc_die_chain
arch/sparc64/kernel/traps.c:		sparc64die_chain
arch/x86_64/kernel/traps.c:		die_chain
drivers/char/ipmi/ipmi_si_intf.c:	xaction_notifier_list
kernel/panic.c:				panic_notifier_list
kernel/profile.c:			task_free_notifier
net/bluetooth/hci_core.c:		hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c:	ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c:	ip_conntrack_expect_chain
net/ipv6/addrconf.c:			inet6addr_chain
net/netfilter/nf_conntrack_core.c:	nf_conntrack_chain
net/netfilter/nf_conntrack_core.c:	nf_conntrack_expect_chain
net/netlink/af_netlink.c:		netlink_chain

  BLOCKING CHAINS
  ---------------
arch/powerpc/platforms/pseries/reconfig.c:	pSeries_reconfig_chain
arch/s390/kernel/process.c:		idle_chain
arch/x86_64/kernel/process.c		idle_notifier
drivers/base/memory.c:			memory_chain
drivers/cpufreq/cpufreq.c		cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c		cpufreq_transition_notifier_list
drivers/macintosh/adb.c:		adb_client_list
drivers/macintosh/via-pmu.c		sleep_notifier_list
drivers/macintosh/via-pmu68k.c		sleep_notifier_list
drivers/macintosh/windfarm_core.c	wf_client_list
drivers/usb/core/notify.c		usb_notifier_list
drivers/video/fbmem.c			fb_notifier_list
kernel/cpu.c				cpu_chain
kernel/module.c				module_notify_list
kernel/profile.c			munmap_notifier
kernel/profile.c			task_exit_notifier
kernel/sys.c				reboot_notifier_list
net/core/dev.c				netdev_chain
net/decnet/dn_dev.c:			dnaddr_chain
net/ipv4/devinet.c:			inetaddr_chain

It's possible that some of these classifications are wrong.  If they are,
please let us know or submit a patch to fix them.  Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)

The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.

[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/alpha/kernel/setup.c

@@ -43,7 +43,7 @@
 #include <asm/setup.h>
 #include <asm/io.h>
 
-extern struct notifier_block *panic_notifier_list;
+extern struct atomic_notifier_head panic_notifier_list;
 static int alpha_panic_event(struct notifier_block *, unsigned long, void *);
 static struct notifier_block alpha_panic_block = {
 	alpha_panic_event,
@@ -500,7 +500,8 @@ setup_arch(char **cmdline_p)
 	}
 
 	/* Register a call for panic conditions. */
-	notifier_chain_register(&panic_notifier_list, &alpha_panic_block);
+	atomic_notifier_chain_register(&panic_notifier_list,
+			&alpha_panic_block);
 
 #ifdef CONFIG_ALPHA_GENERIC
 	/* Assume that we've booted from SRM if we haven't booted from MILO.

arch/arm/mach-omap1/board-netstar.c

@@ -141,7 +141,7 @@ static int __init netstar_late_init(void)
 	/* TODO: Setup front panel switch here */
 
 	/* Setup panic notifier */
-	notifier_chain_register(&panic_notifier_list, &panic_block);
+	atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
 
 	return 0;
 }

arch/arm/mach-omap1/board-voiceblue.c

@@ -235,7 +235,7 @@ static struct notifier_block panic_block = {
 static int __init voiceblue_setup(void)
 {
 	/* Setup panic notifier */
-	notifier_chain_register(&panic_notifier_list, &panic_block);
+	atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
 
 	return 0;
 }

arch/i386/kernel/traps.c

@@ -92,22 +92,21 @@ asmlinkage void spurious_interrupt_bug(void);
 asmlinkage void machine_check(void);
 
 static int kstack_depth_to_print = 24;
-struct notifier_block *i386die_chain;
-static DEFINE_SPINLOCK(die_notifier_lock);
+ATOMIC_NOTIFIER_HEAD(i386die_chain);
 
 int register_die_notifier(struct notifier_block *nb)
 {
-	int err = 0;
-	unsigned long flags;
-
 	vmalloc_sync_all();
-	spin_lock_irqsave(&die_notifier_lock, flags);
-	err = notifier_chain_register(&i386die_chain, nb);
-	spin_unlock_irqrestore(&die_notifier_lock, flags);
-	return err;
+	return atomic_notifier_chain_register(&i386die_chain, nb);
 }
 EXPORT_SYMBOL(register_die_notifier);
 
+int unregister_die_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_unregister(&i386die_chain, nb);
+}
+EXPORT_SYMBOL(unregister_die_notifier);
+
 static inline int valid_stack_ptr(struct thread_info *tinfo, void *p)
 {
 	return	p > (void *)tinfo &&

arch/ia64/kernel/traps.c

@@ -30,19 +30,19 @@ extern spinlock_t timerlist_lock;
 fpswa_interface_t *fpswa_interface;
 EXPORT_SYMBOL(fpswa_interface);
 
-struct notifier_block *ia64die_chain;
+ATOMIC_NOTIFIER_HEAD(ia64die_chain);
 
 int
 register_die_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_register(&ia64die_chain, nb);
+	return atomic_notifier_chain_register(&ia64die_chain, nb);
 }
 EXPORT_SYMBOL_GPL(register_die_notifier);
 
 int
 unregister_die_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_unregister(&ia64die_chain, nb);
+	return atomic_notifier_chain_unregister(&ia64die_chain, nb);
 }
 EXPORT_SYMBOL_GPL(unregister_die_notifier);
 

arch/mips/lasat/setup.c

@@ -165,7 +165,8 @@ void __init plat_setup(void)
 
 	/* Set up panic notifier */
 	for (i = 0; i < sizeof(lasat_panic_block) / sizeof(struct notifier_block); i++)
-		notifier_chain_register(&panic_notifier_list, &lasat_panic_block[i]);
+		atomic_notifier_chain_register(&panic_notifier_list,
+				&lasat_panic_block[i]);
 
 	lasat_reboot_setup();
 

arch/mips/sgi-ip22/ip22-reset.c

@@ -238,7 +238,7 @@ static int __init reboot_setup(void)
 	request_irq(SGI_PANEL_IRQ, panel_int, 0, "Front Panel", NULL);
 	init_timer(&blink_timer);
 	blink_timer.function = blink_timeout;
-	notifier_chain_register(&panic_notifier_list, &panic_block);
+	atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
 
 	return 0;
 }

arch/mips/sgi-ip32/ip32-reset.c

@@ -193,7 +193,7 @@ static __init int ip32_reboot_setup(void)
 
 	init_timer(&blink_timer);
 	blink_timer.function = blink_timeout;
-	notifier_chain_register(&panic_notifier_list, &panic_block);
+	atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
 
 	request_irq(MACEISA_RTC_IRQ, ip32_rtc_int, 0, "rtc", NULL);
 

arch/parisc/kernel/pdc_chassis.c

@@ -150,7 +150,8 @@ void __init parisc_pdc_chassis_init(void)
 
 		if (handle) {
 			/* initialize panic notifier chain */
-			notifier_chain_register(&panic_notifier_list, &pdc_chassis_panic_block);
+			atomic_notifier_chain_register(&panic_notifier_list,
+					&pdc_chassis_panic_block);
 
 			/* initialize reboot notifier chain */
 			register_reboot_notifier(&pdc_chassis_reboot_block);

arch/powerpc/kernel/setup_64.c

@@ -579,7 +579,8 @@ void __init setup_arch(char **cmdline_p)
 	panic_timeout = 180;
 
 	if (ppc_md.panic)
-		notifier_chain_register(&panic_notifier_list, &ppc64_panic_block);
+		atomic_notifier_chain_register(&panic_notifier_list,
+				&ppc64_panic_block);
 
 	init_mm.start_code = PAGE_OFFSET;
 	init_mm.end_code = (unsigned long) _etext;

arch/powerpc/kernel/traps.c

@@ -74,19 +74,19 @@ EXPORT_SYMBOL(__debugger_dabr_match);
 EXPORT_SYMBOL(__debugger_fault_handler);
 #endif
 
-struct notifier_block *powerpc_die_chain;
-static DEFINE_SPINLOCK(die_notifier_lock);
+ATOMIC_NOTIFIER_HEAD(powerpc_die_chain);
 
 int register_die_notifier(struct notifier_block *nb)
 {
-	int err = 0;
-	unsigned long flags;
+	return atomic_notifier_chain_register(&powerpc_die_chain, nb);
+}
+EXPORT_SYMBOL(register_die_notifier);
 
-	spin_lock_irqsave(&die_notifier_lock, flags);
-	err = notifier_chain_register(&powerpc_die_chain, nb);
-	spin_unlock_irqrestore(&die_notifier_lock, flags);
-	return err;
+int unregister_die_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_unregister(&powerpc_die_chain, nb);
 }
+EXPORT_SYMBOL(unregister_die_notifier);
 
 /*
  * Trap & Exception support

arch/powerpc/platforms/pseries/reconfig.c

@@ -94,16 +94,16 @@ static struct device_node *derive_parent(const char *path)
 	return parent;
 }
 
-static struct notifier_block *pSeries_reconfig_chain;
+static BLOCKING_NOTIFIER_HEAD(pSeries_reconfig_chain);
 
 int pSeries_reconfig_notifier_register(struct notifier_block *nb)
 {
-	return notifier_chain_register(&pSeries_reconfig_chain, nb);
+	return blocking_notifier_chain_register(&pSeries_reconfig_chain, nb);
 }
 
 void pSeries_reconfig_notifier_unregister(struct notifier_block *nb)
 {
-	notifier_chain_unregister(&pSeries_reconfig_chain, nb);
+	blocking_notifier_chain_unregister(&pSeries_reconfig_chain, nb);
 }
 
 static int pSeries_reconfig_add_node(const char *path, struct property *proplist)
@@ -131,7 +131,7 @@ static int pSeries_reconfig_add_node(const char *path, struct property *proplist
 		goto out_err;
 	}
 
-	err = notifier_call_chain(&pSeries_reconfig_chain,
+	err = blocking_notifier_call_chain(&pSeries_reconfig_chain,
 				  PSERIES_RECONFIG_ADD, np);
 	if (err == NOTIFY_BAD) {
 		printk(KERN_ERR "Failed to add device node %s\n", path);
@@ -171,7 +171,7 @@ static int pSeries_reconfig_remove_node(struct device_node *np)
 
 	remove_node_proc_entries(np);
 
-	notifier_call_chain(&pSeries_reconfig_chain,
+	blocking_notifier_call_chain(&pSeries_reconfig_chain,
 			    PSERIES_RECONFIG_REMOVE, np);
 	of_detach_node(np);
 

arch/ppc/platforms/prep_setup.c

@@ -736,7 +736,7 @@ ibm_statusled_progress(char *s, unsigned short hex)
 		hex = 0xfff;
 		if (!notifier_installed) {
 			++notifier_installed;
-			notifier_chain_register(&panic_notifier_list,
+			atomic_notifier_chain_register(&panic_notifier_list,
 						&ibm_statusled_block);
 		}
 	}

arch/s390/kernel/process.c

@@ -76,17 +76,17 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
 /*
  * Need to know about CPUs going idle?
  */
-static struct notifier_block *idle_chain;
+static ATOMIC_NOTIFIER_HEAD(idle_chain);
 
 int register_idle_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_register(&idle_chain, nb);
+	return atomic_notifier_chain_register(&idle_chain, nb);
 }
 EXPORT_SYMBOL(register_idle_notifier);
 
 int unregister_idle_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_unregister(&idle_chain, nb);
+	return atomic_notifier_chain_unregister(&idle_chain, nb);
 }
 EXPORT_SYMBOL(unregister_idle_notifier);
 
@@ -95,7 +95,7 @@ void do_monitor_call(struct pt_regs *regs, long interruption_code)
 	/* disable monitor call class 0 */
 	__ctl_clear_bit(8, 15);
 
-	notifier_call_chain(&idle_chain, CPU_NOT_IDLE,
+	atomic_notifier_call_chain(&idle_chain, CPU_NOT_IDLE,
 			    (void *)(long) smp_processor_id());
 }
 
@@ -116,7 +116,8 @@ static void default_idle(void)
 		return;
 	}
 
-	rc = notifier_call_chain(&idle_chain, CPU_IDLE, (void *)(long) cpu);
+	rc = atomic_notifier_call_chain(&idle_chain,
+			CPU_IDLE, (void *)(long) cpu);
 	if (rc != NOTIFY_OK && rc != NOTIFY_DONE)
 		BUG();
 	if (rc != NOTIFY_OK) {

arch/sparc64/kernel/traps.c

@@ -43,18 +43,19 @@
 #include <linux/kmod.h>
 #endif
 
-struct notifier_block *sparc64die_chain;
-static DEFINE_SPINLOCK(die_notifier_lock);
+ATOMIC_NOTIFIER_HEAD(sparc64die_chain);
 
 int register_die_notifier(struct notifier_block *nb)
 {
-	int err = 0;
-	unsigned long flags;
-	spin_lock_irqsave(&die_notifier_lock, flags);
-	err = notifier_chain_register(&sparc64die_chain, nb);
-	spin_unlock_irqrestore(&die_notifier_lock, flags);
-	return err;
+	return atomic_notifier_chain_register(&sparc64die_chain, nb);
 }
+EXPORT_SYMBOL(register_die_notifier);
+
+int unregister_die_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_unregister(&sparc64die_chain, nb);
+}
+EXPORT_SYMBOL(unregister_die_notifier);
 
 /* When an irrecoverable trap occurs at tl > 0, the trap entry
  * code logs the trap state registers at every level in the trap

arch/um/drivers/mconsole_kern.c

@@ -762,7 +762,8 @@ static struct notifier_block panic_exit_notifier = {
 
 static int add_notifier(void)
 {
-	notifier_chain_register(&panic_notifier_list, &panic_exit_notifier);
+	atomic_notifier_chain_register(&panic_notifier_list,
+			&panic_exit_notifier);
 	return(0);
 }
 

arch/um/kernel/um_arch.c

@@ -477,7 +477,8 @@ static struct notifier_block panic_exit_notifier = {
 
 void __init setup_arch(char **cmdline_p)
 {
-	notifier_chain_register(&panic_notifier_list, &panic_exit_notifier);
+	atomic_notifier_chain_register(&panic_notifier_list,
+			&panic_exit_notifier);
 	paging_init();
         strlcpy(saved_command_line, command_line, COMMAND_LINE_SIZE);
  	*cmdline_p = command_line;

arch/x86_64/kernel/process.c

@@ -66,24 +66,17 @@ EXPORT_SYMBOL(boot_option_idle_override);
 void (*pm_idle)(void);
 static DEFINE_PER_CPU(unsigned int, cpu_idle_state);
 
-static struct notifier_block *idle_notifier;
-static DEFINE_SPINLOCK(idle_notifier_lock);
+static ATOMIC_NOTIFIER_HEAD(idle_notifier);
 
 void idle_notifier_register(struct notifier_block *n)
 {
-	unsigned long flags;
-	spin_lock_irqsave(&idle_notifier_lock, flags);
-	notifier_chain_register(&idle_notifier, n);
-	spin_unlock_irqrestore(&idle_notifier_lock, flags);
+	atomic_notifier_chain_register(&idle_notifier, n);
 }
 EXPORT_SYMBOL_GPL(idle_notifier_register);
 
 void idle_notifier_unregister(struct notifier_block *n)
 {
-	unsigned long flags;
-	spin_lock_irqsave(&idle_notifier_lock, flags);
-	notifier_chain_unregister(&idle_notifier, n);
-	spin_unlock_irqrestore(&idle_notifier_lock, flags);
+	atomic_notifier_chain_unregister(&idle_notifier, n);
 }
 EXPORT_SYMBOL(idle_notifier_unregister);
 
@@ -93,13 +86,13 @@ static DEFINE_PER_CPU(enum idle_state, idle_state) = CPU_NOT_IDLE;
 void enter_idle(void)
 {
 	__get_cpu_var(idle_state) = CPU_IDLE;
-	notifier_call_chain(&idle_notifier, IDLE_START, NULL);
+	atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
 }
 
 static void __exit_idle(void)
 {
 	__get_cpu_var(idle_state) = CPU_NOT_IDLE;
-	notifier_call_chain(&idle_notifier, IDLE_END, NULL);
+	atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
 }
 
 /* Called from interrupts to signify idle end */

arch/x86_64/kernel/traps.c

@@ -69,20 +69,20 @@ asmlinkage void alignment_check(void);
 asmlinkage void machine_check(void);
 asmlinkage void spurious_interrupt_bug(void);
 
-struct notifier_block *die_chain;
-static DEFINE_SPINLOCK(die_notifier_lock);
+ATOMIC_NOTIFIER_HEAD(die_chain);
 
 int register_die_notifier(struct notifier_block *nb)
 {
-	int err = 0;
-	unsigned long flags;
-
 	vmalloc_sync_all();
-	spin_lock_irqsave(&die_notifier_lock, flags);
-	err = notifier_chain_register(&die_chain, nb);
-	spin_unlock_irqrestore(&die_notifier_lock, flags);
-	return err;
+	return atomic_notifier_chain_register(&die_chain, nb);
+}
+EXPORT_SYMBOL(register_die_notifier);
+
+int unregister_die_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_unregister(&die_chain, nb);
 }
+EXPORT_SYMBOL(unregister_die_notifier);
 
 static inline void conditional_sti(struct pt_regs *regs)
 {

arch/xtensa/platform-iss/setup.c

@@ -108,5 +108,5 @@ static struct notifier_block iss_panic_block = {
 
 void __init platform_setup(char **p_cmdline)
 {
-	notifier_chain_register(&panic_notifier_list, &iss_panic_block);
+	atomic_notifier_chain_register(&panic_notifier_list, &iss_panic_block);
 }

drivers/base/memory.c

@@ -47,16 +47,16 @@ static struct kset_uevent_ops memory_uevent_ops = {
 	.uevent		= memory_uevent,
 };
 
-static struct notifier_block *memory_chain;
+static BLOCKING_NOTIFIER_HEAD(memory_chain);
 
 int register_memory_notifier(struct notifier_block *nb)
 {
-        return notifier_chain_register(&memory_chain, nb);
+        return blocking_notifier_chain_register(&memory_chain, nb);
 }
 
 void unregister_memory_notifier(struct notifier_block *nb)
 {
-        notifier_chain_unregister(&memory_chain, nb);
+        blocking_notifier_chain_unregister(&memory_chain, nb);
 }
 
 /*
@@ -140,7 +140,7 @@ static ssize_t show_mem_state(struct sys_device *dev, char *buf)
 
 static inline int memory_notify(unsigned long val, void *v)
 {
-	return notifier_call_chain(&memory_chain, val, v);
+	return blocking_notifier_call_chain(&memory_chain, val, v);
 }
 
 /*

drivers/char/ipmi/ipmi_msghandler.c

@@ -3744,7 +3744,7 @@ static int ipmi_init_msghandler(void)
 	ipmi_timer.expires = jiffies + IPMI_TIMEOUT_JIFFIES;
 	add_timer(&ipmi_timer);
 
-	notifier_chain_register(&panic_notifier_list, &panic_block);
+	atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
 
 	initialized = 1;
 
@@ -3764,7 +3764,7 @@ static __exit void cleanup_ipmi(void)
 	if (!initialized)
 		return;
 
-	notifier_chain_unregister(&panic_notifier_list, &panic_block);
+	atomic_notifier_chain_unregister(&panic_notifier_list, &panic_block);
 
 	/* This can't be called if any interfaces exist, so no worry about
 	   shutting down the interfaces. */

drivers/char/ipmi/ipmi_si_intf.c

@@ -237,10 +237,10 @@ struct smi_info
 
 static int try_smi_init(struct smi_info *smi);
 
-static struct notifier_block *xaction_notifier_list;
+static ATOMIC_NOTIFIER_HEAD(xaction_notifier_list);
 static int register_xaction_notifier(struct notifier_block * nb)
 {
-	return notifier_chain_register(&xaction_notifier_list, nb);
+	return atomic_notifier_chain_register(&xaction_notifier_list, nb);
 }
 
 static void si_restart_short_timer(struct smi_info *smi_info);
@@ -302,7 +302,8 @@ static enum si_sm_result start_next_msg(struct smi_info *smi_info)
 		do_gettimeofday(&t);
 		printk("**Start2: %d.%9.9d\n", t.tv_sec, t.tv_usec);
 #endif
-		err = notifier_call_chain(&xaction_notifier_list, 0, smi_info);
+		err = atomic_notifier_call_chain(&xaction_notifier_list,
+				0, smi_info);
 		if (err & NOTIFY_STOP_MASK) {
 			rv = SI_SM_CALL_WITHOUT_DELAY;
 			goto out;

drivers/char/ipmi/ipmi_watchdog.c

@@ -1158,7 +1158,8 @@ static int __init ipmi_wdog_init(void)
 	}
 
 	register_reboot_notifier(&wdog_reboot_notifier);
-	notifier_chain_register(&panic_notifier_list, &wdog_panic_notifier);
+	atomic_notifier_chain_register(&panic_notifier_list,
+			&wdog_panic_notifier);
 
 	printk(KERN_INFO PFX "driver initialized\n");
 
@@ -1176,7 +1177,8 @@ static __exit void ipmi_unregister_watchdog(void)
 		release_nmi(&ipmi_nmi_handler);
 #endif
 
-	notifier_chain_unregister(&panic_notifier_list, &wdog_panic_notifier);
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+			&wdog_panic_notifier);
 	unregister_reboot_notifier(&wdog_reboot_notifier);
 
 	if (! watchdog_user)

drivers/cpufreq/cpufreq.c

@@ -52,9 +52,8 @@ static void handle_update(void *data);
  * changes to devices when the CPU clock speed changes.
  * The mutex locks both lists.
  */
-static struct notifier_block *cpufreq_policy_notifier_list;
-static struct notifier_block *cpufreq_transition_notifier_list;
-static DECLARE_RWSEM (cpufreq_notifier_rwsem);
+static BLOCKING_NOTIFIER_HEAD(cpufreq_policy_notifier_list);
+static BLOCKING_NOTIFIER_HEAD(cpufreq_transition_notifier_list);
 
 
 static LIST_HEAD(cpufreq_governor_list);
@@ -247,8 +246,6 @@ void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
 	dprintk("notification %u of frequency transition to %u kHz\n",
 		state, freqs->new);
 
-	down_read(&cpufreq_notifier_rwsem);
-
 	policy = cpufreq_cpu_data[freqs->cpu];
 	switch (state) {
 
@@ -266,20 +263,19 @@ void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
 				freqs->old = policy->cur;
 			}
 		}
-		notifier_call_chain(&cpufreq_transition_notifier_list,
-					CPUFREQ_PRECHANGE, freqs);
+		blocking_notifier_call_chain(&cpufreq_transition_notifier_list,
+				CPUFREQ_PRECHANGE, freqs);
 		adjust_jiffies(CPUFREQ_PRECHANGE, freqs);
 		break;
 
 	case CPUFREQ_POSTCHANGE:
 		adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
-		notifier_call_chain(&cpufreq_transition_notifier_list,
-					CPUFREQ_POSTCHANGE, freqs);
+		blocking_notifier_call_chain(&cpufreq_transition_notifier_list,
+				CPUFREQ_POSTCHANGE, freqs);
 		if (likely(policy) && likely(policy->cpu == freqs->cpu))
 			policy->cur = freqs->new;
 		break;
 	}
-	up_read(&cpufreq_notifier_rwsem);
 }
 EXPORT_SYMBOL_GPL(cpufreq_notify_transition);
 
@@ -1007,7 +1003,7 @@ static int cpufreq_suspend(struct sys_device * sysdev, pm_message_t pmsg)
 		freqs.old = cpu_policy->cur;
 		freqs.new = cur_freq;
 
-		notifier_call_chain(&cpufreq_transition_notifier_list,
+		blocking_notifier_call_chain(&cpufreq_transition_notifier_list,
 				    CPUFREQ_SUSPENDCHANGE, &freqs);
 		adjust_jiffies(CPUFREQ_SUSPENDCHANGE, &freqs);
 
@@ -1088,7 +1084,8 @@ static int cpufreq_resume(struct sys_device * sysdev)
 			freqs.old = cpu_policy->cur;
 			freqs.new = cur_freq;
 
-			notifier_call_chain(&cpufreq_transition_notifier_list,
+			blocking_notifier_call_chain(
+					&cpufreq_transition_notifier_list,
 					CPUFREQ_RESUMECHANGE, &freqs);
 			adjust_jiffies(CPUFREQ_RESUMECHANGE, &freqs);
 
@@ -1125,24 +1122,24 @@ static struct sysdev_driver cpufreq_sysdev_driver = {
  *      changes in cpufreq policy.
  *
  *	This function may sleep, and has the same return conditions as
- *	notifier_chain_register.
+ *	blocking_notifier_chain_register.
  */
 int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
 {
 	int ret;
 
-	down_write(&cpufreq_notifier_rwsem);
 	switch (list) {
 	case CPUFREQ_TRANSITION_NOTIFIER:
-		ret = notifier_chain_register(&cpufreq_transition_notifier_list, nb);
+		ret = blocking_notifier_chain_register(
+				&cpufreq_transition_notifier_list, nb);
 		break;
 	case CPUFREQ_POLICY_NOTIFIER:
-		ret = notifier_chain_register(&cpufreq_policy_notifier_list, nb);
+		ret = blocking_notifier_chain_register(
+				&cpufreq_policy_notifier_list, nb);
 		break;
 	default:
 		ret = -EINVAL;
 	}
-	up_write(&cpufreq_notifier_rwsem);
 
 	return ret;
 }
@@ -1157,24 +1154,24 @@ EXPORT_SYMBOL(cpufreq_register_notifier);
  *	Remove a driver from the CPU frequency notifier list.
  *
  *	This function may sleep, and has the same return conditions as
- *	notifier_chain_unregister.
+ *	blocking_notifier_chain_unregister.
  */
 int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
 {
 	int ret;
 
-	down_write(&cpufreq_notifier_rwsem);
 	switch (list) {
 	case CPUFREQ_TRANSITION_NOTIFIER:
-		ret = notifier_chain_unregister(&cpufreq_transition_notifier_list, nb);
+		ret = blocking_notifier_chain_unregister(
+				&cpufreq_transition_notifier_list, nb);
 		break;
 	case CPUFREQ_POLICY_NOTIFIER:
-		ret = notifier_chain_unregister(&cpufreq_policy_notifier_list, nb);
+		ret = blocking_notifier_chain_unregister(
+				&cpufreq_policy_notifier_list, nb);
 		break;
 	default:
 		ret = -EINVAL;
 	}
-	up_write(&cpufreq_notifier_rwsem);
 
 	return ret;
 }
@@ -1346,29 +1343,23 @@ static int __cpufreq_set_policy(struct cpufreq_policy *data, struct cpufreq_poli
 	if (ret)
 		goto error_out;
 
-	down_read(&cpufreq_notifier_rwsem);
-
 	/* adjust if necessary - all reasons */
-	notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_ADJUST,
-			    policy);
+	blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+			CPUFREQ_ADJUST, policy);
 
 	/* adjust if necessary - hardware incompatibility*/
-	notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_INCOMPATIBLE,
-			    policy);
+	blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+			CPUFREQ_INCOMPATIBLE, policy);
 
 	/* verify the cpu speed can be set within this limit,
 	   which might be different to the first one */
 	ret = cpufreq_driver->verify(policy);
-	if (ret) {
-		up_read(&cpufreq_notifier_rwsem);
+	if (ret)
 		goto error_out;
-	}
 
 	/* notification of the new policy */
-	notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_NOTIFY,
-			    policy);
-
-	up_read(&cpufreq_notifier_rwsem);
+	blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+			CPUFREQ_NOTIFY, policy);
 
 	data->min = policy->min;
 	data->max = policy->max;

drivers/firmware/dcdbas.c

@@ -484,26 +484,15 @@ static void dcdbas_host_control(void)
 static int dcdbas_reboot_notify(struct notifier_block *nb, unsigned long code,
 				void *unused)
 {
-	static unsigned int notify_cnt = 0;
-
 	switch (code) {
 	case SYS_DOWN:
 	case SYS_HALT:
 	case SYS_POWER_OFF:
 		if (host_control_on_shutdown) {
 			/* firmware is going to perform host control action */
-			if (++notify_cnt == 2) {
-				printk(KERN_WARNING
-				       "Please wait for shutdown "
-				       "action to complete...\n");
-				dcdbas_host_control();
-			}
-			/*
-			 * register again and initiate the host control
-			 * action on the second notification to allow
-			 * everyone that registered to be notified
-			 */
-			register_reboot_notifier(nb);
+			printk(KERN_WARNING "Please wait for shutdown "
+			       "action to complete...\n");
+			dcdbas_host_control();
 		}
 		break;
 	}
@@ -514,7 +503,7 @@ static int dcdbas_reboot_notify(struct notifier_block *nb, unsigned long code,
 static struct notifier_block dcdbas_reboot_nb = {
 	.notifier_call = dcdbas_reboot_notify,
 	.next = NULL,
-	.priority = 0
+	.priority = INT_MIN
 };
 
 static DCDBAS_BIN_ATTR_RW(smi_data);

drivers/macintosh/adb.c

@@ -80,7 +80,7 @@ static struct adb_driver *adb_driver_list[] = {
 static struct class *adb_dev_class;
 
 struct adb_driver *adb_controller;
-struct notifier_block *adb_client_list = NULL;
+BLOCKING_NOTIFIER_HEAD(adb_client_list);
 static int adb_got_sleep;
 static int adb_inited;
 static pid_t adb_probe_task_pid;
@@ -354,7 +354,8 @@ adb_notify_sleep(struct pmu_sleep_notifier *self, int when)
 		/* Stop autopoll */
 		if (adb_controller->autopoll)
 			adb_controller->autopoll(0);
-		ret = notifier_call_chain(&adb_client_list, ADB_MSG_POWERDOWN, NULL);
+		ret = blocking_notifier_call_chain(&adb_client_list,
+				ADB_MSG_POWERDOWN, NULL);
 		if (ret & NOTIFY_STOP_MASK) {
 			up(&adb_probe_mutex);
 			return PBOOK_SLEEP_REFUSE;
@@ -391,7 +392,8 @@ do_adb_reset_bus(void)
 	if (adb_controller->autopoll)
 		adb_controller->autopoll(0);
 
-	nret = notifier_call_chain(&adb_client_list, ADB_MSG_PRE_RESET, NULL);
+	nret = blocking_notifier_call_chain(&adb_client_list,
+			ADB_MSG_PRE_RESET, NULL);
 	if (nret & NOTIFY_STOP_MASK) {
 		if (adb_controller->autopoll)
 			adb_controller->autopoll(autopoll_devs);
@@ -426,7 +428,8 @@ do_adb_reset_bus(void)
 	}
 	up(&adb_handler_sem);
 
-	nret = notifier_call_chain(&adb_client_list, ADB_MSG_POST_RESET, NULL);
+	nret = blocking_notifier_call_chain(&adb_client_list,
+			ADB_MSG_POST_RESET, NULL);
 	if (nret & NOTIFY_STOP_MASK)
 		return -EBUSY;
 	

drivers/macintosh/adbhid.c

@@ -1214,7 +1214,8 @@ static int __init adbhid_init(void)
 
 	adbhid_probe();
 
-	notifier_chain_register(&adb_client_list, &adbhid_adb_notifier);
+	blocking_notifier_chain_register(&adb_client_list,
+			&adbhid_adb_notifier);
 
 	return 0;
 }

drivers/macintosh/via-pmu.c

@@ -187,7 +187,7 @@ extern int disable_kernel_backlight;
 
 int __fake_sleep;
 int asleep;
-struct notifier_block *sleep_notifier_list;
+BLOCKING_NOTIFIER_HEAD(sleep_notifier_list);
 
 #ifdef CONFIG_ADB
 static int adb_dev_map = 0;

drivers/macintosh/via-pmu68k.c

@@ -102,7 +102,7 @@ static int pmu_kind = PMU_UNKNOWN;
 static int pmu_fully_inited = 0;
 
 int asleep;
-struct notifier_block *sleep_notifier_list;
+BLOCKING_NOTIFIER_HEAD(sleep_notifier_list);
 
 static int pmu_probe(void);
 static int pmu_init(void);
@@ -913,7 +913,8 @@ int powerbook_sleep(void)
 	struct adb_request sleep_req;
 
 	/* Notify device drivers */
-	ret = notifier_call_chain(&sleep_notifier_list, PBOOK_SLEEP, NULL);
+	ret = blocking_notifier_call_chain(&sleep_notifier_list,
+			PBOOK_SLEEP, NULL);
 	if (ret & NOTIFY_STOP_MASK)
 		return -EBUSY;
 
@@ -984,7 +985,7 @@ int powerbook_sleep(void)
 			enable_irq(i);
 
 	/* Notify drivers */
-	notifier_call_chain(&sleep_notifier_list, PBOOK_WAKE, NULL);
+	blocking_notifier_call_chain(&sleep_notifier_list, PBOOK_WAKE, NULL);
 
 	/* reenable ADB autopoll */
 	pmu_adb_autopoll(adb_dev_map);

drivers/macintosh/windfarm_core.c

@@ -52,7 +52,7 @@
 static LIST_HEAD(wf_controls);
 static LIST_HEAD(wf_sensors);
 static DEFINE_MUTEX(wf_lock);
-static struct notifier_block *wf_client_list;
+static BLOCKING_NOTIFIER_HEAD(wf_client_list);
 static int wf_client_count;
 static unsigned int wf_overtemp;
 static unsigned int wf_overtemp_counter;
@@ -68,7 +68,7 @@ static struct platform_device wf_platform_device = {
 
 static inline void wf_notify(int event, void *param)
 {
-	notifier_call_chain(&wf_client_list, event, param);
+	blocking_notifier_call_chain(&wf_client_list, event, param);
 }
 
 int wf_critical_overtemp(void)
@@ -398,7 +398,7 @@ int wf_register_client(struct notifier_block *nb)
 	struct wf_sensor *sr;
 
 	mutex_lock(&wf_lock);
-	rc = notifier_chain_register(&wf_client_list, nb);
+	rc = blocking_notifier_chain_register(&wf_client_list, nb);
 	if (rc != 0)
 		goto bail;
 	wf_client_count++;
@@ -417,7 +417,7 @@ EXPORT_SYMBOL_GPL(wf_register_client);
 int wf_unregister_client(struct notifier_block *nb)
 {
 	mutex_lock(&wf_lock);
-	notifier_chain_unregister(&wf_client_list, nb);
+	blocking_notifier_chain_unregister(&wf_client_list, nb);
 	wf_client_count++;
 	if (wf_client_count == 0)
 		wf_stop_thread();

drivers/misc/ibmasm/heartbeat.c

@@ -52,12 +52,13 @@ static struct notifier_block panic_notifier = { panic_happened, NULL, 1 };
 
 void ibmasm_register_panic_notifier(void)
 {
-	notifier_chain_register(&panic_notifier_list, &panic_notifier);
+	atomic_notifier_chain_register(&panic_notifier_list, &panic_notifier);
 }
 
 void ibmasm_unregister_panic_notifier(void)
 {
-	notifier_chain_unregister(&panic_notifier_list, &panic_notifier);
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+			&panic_notifier);
 }
 
 

drivers/net/bonding/bond_main.c

@@ -3159,7 +3159,7 @@ static int bond_slave_netdev_event(unsigned long event, struct net_device *slave
  * bond_netdev_event: handle netdev notifier chain events.
  *
  * This function receives events for the netdev chain.  The caller (an
- * ioctl handler calling notifier_call_chain) holds the necessary
+ * ioctl handler calling blocking_notifier_call_chain) holds the necessary
  * locks for us to safely manipulate the slave devices (RTNL lock,
  * dev_probe_lock).
  */

drivers/parisc/led.c

@@ -499,11 +499,16 @@ static int led_halt(struct notifier_block *, unsigned long, void *);
 static struct notifier_block led_notifier = {
 	.notifier_call = led_halt,
 };
+static int notifier_disabled = 0;
 
 static int led_halt(struct notifier_block *nb, unsigned long event, void *buf) 
 {
 	char *txt;
-	
+
+	if (notifier_disabled)
+		return NOTIFY_OK;
+
+	notifier_disabled = 1;
 	switch (event) {
 	case SYS_RESTART:	txt = "SYSTEM RESTART";
 				break;
@@ -527,7 +532,6 @@ static int led_halt(struct notifier_block *nb, unsigned long event, void *buf)
 		if (led_func_ptr)
 			led_func_ptr(0xff); /* turn all LEDs ON */
 	
-	unregister_reboot_notifier(&led_notifier);
 	return NOTIFY_OK;
 }
 
@@ -758,6 +762,12 @@ not_found:
 	return 1;
 }
 
+static void __exit led_exit(void)
+{
+	unregister_reboot_notifier(&led_notifier);
+	return;
+}
+
 #ifdef CONFIG_PROC_FS
 module_init(led_create_procfs)
 #endif

drivers/parisc/power.c

@@ -251,7 +251,8 @@ static int __init power_init(void)
 	}
 
 	/* Register a call for panic conditions. */
-	notifier_chain_register(&panic_notifier_list, &parisc_panic_block);
+	atomic_notifier_chain_register(&panic_notifier_list,
+			&parisc_panic_block);
 
 	tasklet_enable(&power_tasklet);
 
@@ -264,7 +265,8 @@ static void __exit power_exit(void)
 		return;
 
 	tasklet_disable(&power_tasklet);
-	notifier_chain_unregister(&panic_notifier_list, &parisc_panic_block);
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+			&parisc_panic_block);
 	power_tasklet.func = NULL;
 	pdc_soft_power_button(0);
 }

drivers/scsi/gdth.c

@@ -671,7 +671,7 @@ static struct file_operations gdth_fops = {
 static struct notifier_block gdth_notifier = {
     gdth_halt, NULL, 0
 };
-
+static int notifier_disabled = 0;
 
 static void gdth_delay(int milliseconds)
 {
@@ -4595,13 +4595,13 @@ static int __init gdth_detect(struct scsi_host_template *shtp)
         add_timer(&gdth_timer);
 #endif
         major = register_chrdev(0,"gdth",&gdth_fops);
+        notifier_disabled = 0;
         register_reboot_notifier(&gdth_notifier);
     }
     gdth_polling = FALSE;
     return gdth_ctr_vcount;
 }
 
-
 static int gdth_release(struct Scsi_Host *shp)
 {
     int hanum;
@@ -5632,10 +5632,14 @@ static int gdth_halt(struct notifier_block *nb, ulong event, void *buf)
     char            cmnd[MAX_COMMAND_SIZE];   
 #endif
 
+    if (notifier_disabled)
+    	return NOTIFY_OK;
+
     TRACE2(("gdth_halt() event %d\n",(int)event));
     if (event != SYS_RESTART && event != SYS_HALT && event != SYS_POWER_OFF)
         return NOTIFY_DONE;
 
+    notifier_disabled = 1;
     printk("GDT-HA: Flushing all host drives .. ");
     for (hanum = 0; hanum < gdth_ctr_count; ++hanum) {
         gdth_flush(hanum);
@@ -5679,7 +5683,6 @@ static int gdth_halt(struct notifier_block *nb, ulong event, void *buf)
 #ifdef GDTH_STATISTICS
     del_timer(&gdth_timer);
 #endif
-    unregister_reboot_notifier(&gdth_notifier);
     return NOTIFY_OK;
 }
 

drivers/usb/core/notify.c

@@ -16,57 +16,7 @@
 #include <linux/mutex.h>
 #include "usb.h"
 
-
-static struct notifier_block *usb_notifier_list;
-static DEFINE_MUTEX(usb_notifier_lock);
-
-static void usb_notifier_chain_register(struct notifier_block **list,
-					struct notifier_block *n)
-{
-	mutex_lock(&usb_notifier_lock);
-	while (*list) {
-		if (n->priority > (*list)->priority)
-			break;
-		list = &((*list)->next);
-	}
-	n->next = *list;
-	*list = n;
-	mutex_unlock(&usb_notifier_lock);
-}
-
-static void usb_notifier_chain_unregister(struct notifier_block **nl,
-				   struct notifier_block *n)
-{
-	mutex_lock(&usb_notifier_lock);
-	while ((*nl)!=NULL) {
-		if ((*nl)==n) {
-			*nl = n->next;
-			goto exit;
-		}
-		nl=&((*nl)->next);
-	}
-exit:
-	mutex_unlock(&usb_notifier_lock);
-}
-
-static int usb_notifier_call_chain(struct notifier_block **n,
-				   unsigned long val, void *v)
-{
-	int ret=NOTIFY_DONE;
-	struct notifier_block *nb = *n;
-
-	mutex_lock(&usb_notifier_lock);
-	while (nb) {
-		ret = nb->notifier_call(nb,val,v);
-		if (ret&NOTIFY_STOP_MASK) {
-			goto exit;
-		}
-		nb = nb->next;
-	}
-exit:
-	mutex_unlock(&usb_notifier_lock);
-	return ret;
-}
+static BLOCKING_NOTIFIER_HEAD(usb_notifier_list);
 
 /**
  * usb_register_notify - register a notifier callback whenever a usb change happens
@@ -76,7 +26,7 @@ exit:
  */
 void usb_register_notify(struct notifier_block *nb)
 {
-	usb_notifier_chain_register(&usb_notifier_list, nb);
+	blocking_notifier_chain_register(&usb_notifier_list, nb);
 }
 EXPORT_SYMBOL_GPL(usb_register_notify);
 
@@ -89,27 +39,28 @@ EXPORT_SYMBOL_GPL(usb_register_notify);
  */
 void usb_unregister_notify(struct notifier_block *nb)
 {
-	usb_notifier_chain_unregister(&usb_notifier_list, nb);
+	blocking_notifier_chain_unregister(&usb_notifier_list, nb);
 }
 EXPORT_SYMBOL_GPL(usb_unregister_notify);
 
 
 void usb_notify_add_device(struct usb_device *udev)
 {
-	usb_notifier_call_chain(&usb_notifier_list, USB_DEVICE_ADD, udev);
+	blocking_notifier_call_chain(&usb_notifier_list, USB_DEVICE_ADD, udev);
 }
 
 void usb_notify_remove_device(struct usb_device *udev)
 {
-	usb_notifier_call_chain(&usb_notifier_list, USB_DEVICE_REMOVE, udev);
+	blocking_notifier_call_chain(&usb_notifier_list,
+			USB_DEVICE_REMOVE, udev);
 }
 
 void usb_notify_add_bus(struct usb_bus *ubus)
 {
-	usb_notifier_call_chain(&usb_notifier_list, USB_BUS_ADD, ubus);
+	blocking_notifier_call_chain(&usb_notifier_list, USB_BUS_ADD, ubus);
 }
 
 void usb_notify_remove_bus(struct usb_bus *ubus)
 {
-	usb_notifier_call_chain(&usb_notifier_list, USB_BUS_REMOVE, ubus);
+	blocking_notifier_call_chain(&usb_notifier_list, USB_BUS_REMOVE, ubus);
 }

drivers/video/fbmem.c

@@ -55,7 +55,7 @@
 
 #define FBPIXMAPSIZE	(1024 * 8)
 
-static struct notifier_block *fb_notifier_list;
+static BLOCKING_NOTIFIER_HEAD(fb_notifier_list);
 struct fb_info *registered_fb[FB_MAX];
 int num_registered_fb;
 
@@ -784,7 +784,7 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var)
 
 		    event.info = info;
 		    event.data = &mode1;
-		    ret = notifier_call_chain(&fb_notifier_list,
+		    ret = blocking_notifier_call_chain(&fb_notifier_list,
 					      FB_EVENT_MODE_DELETE, &event);
 		}
 
@@ -830,8 +830,8 @@ fb_set_var(struct fb_info *info, struct fb_var_screeninfo *var)
 
 				info->flags &= ~FBINFO_MISC_USEREVENT;
 				event.info = info;
-				notifier_call_chain(&fb_notifier_list, evnt,
-						    &event);
+				blocking_notifier_call_chain(&fb_notifier_list,
+						evnt, &event);
 			}
 		}
 	}
@@ -854,7 +854,8 @@ fb_blank(struct fb_info *info, int blank)
 
 		event.info = info;
 		event.data = ␣
-		notifier_call_chain(&fb_notifier_list, FB_EVENT_BLANK, &event);
+		blocking_notifier_call_chain(&fb_notifier_list,
+				FB_EVENT_BLANK, &event);
 	}
 
  	return ret;
@@ -925,7 +926,7 @@ fb_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 		con2fb.framebuffer = -1;
 		event.info = info;
 		event.data = &con2fb;
-		notifier_call_chain(&fb_notifier_list,
+		blocking_notifier_call_chain(&fb_notifier_list,
 				    FB_EVENT_GET_CONSOLE_MAP, &event);
 		return copy_to_user(argp, &con2fb,
 				    sizeof(con2fb)) ? -EFAULT : 0;
@@ -944,7 +945,7 @@ fb_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 		    return -EINVAL;
 		event.info = info;
 		event.data = &con2fb;
-		return notifier_call_chain(&fb_notifier_list,
+		return blocking_notifier_call_chain(&fb_notifier_list,
 					   FB_EVENT_SET_CONSOLE_MAP,
 					   &event);
 	case FBIOBLANK:
@@ -1324,7 +1325,7 @@ register_framebuffer(struct fb_info *fb_info)
 	devfs_mk_cdev(MKDEV(FB_MAJOR, i),
 			S_IFCHR | S_IRUGO | S_IWUGO, "fb/%d", i);
 	event.info = fb_info;
-	notifier_call_chain(&fb_notifier_list,
+	blocking_notifier_call_chain(&fb_notifier_list,
 			    FB_EVENT_FB_REGISTERED, &event);
 	return 0;
 }
@@ -1366,7 +1367,7 @@ unregister_framebuffer(struct fb_info *fb_info)
  */
 int fb_register_client(struct notifier_block *nb)
 {
-	return notifier_chain_register(&fb_notifier_list, nb);
+	return blocking_notifier_chain_register(&fb_notifier_list, nb);
 }
 
 /**
@@ -1375,7 +1376,7 @@ int fb_register_client(struct notifier_block *nb)
  */
 int fb_unregister_client(struct notifier_block *nb)
 {
-	return notifier_chain_unregister(&fb_notifier_list, nb);
+	return blocking_notifier_chain_unregister(&fb_notifier_list, nb);
 }
 
 /**
@@ -1393,11 +1394,13 @@ void fb_set_suspend(struct fb_info *info, int state)
 
 	event.info = info;
 	if (state) {
-		notifier_call_chain(&fb_notifier_list, FB_EVENT_SUSPEND, &event);
+		blocking_notifier_call_chain(&fb_notifier_list,
+				FB_EVENT_SUSPEND, &event);
 		info->state = FBINFO_STATE_SUSPENDED;
 	} else {
 		info->state = FBINFO_STATE_RUNNING;
-		notifier_call_chain(&fb_notifier_list, FB_EVENT_RESUME, &event);
+		blocking_notifier_call_chain(&fb_notifier_list,
+				FB_EVENT_RESUME, &event);
 	}
 }
 
@@ -1469,7 +1472,7 @@ int fb_new_modelist(struct fb_info *info)
 
 	if (!list_empty(&info->modelist)) {
 		event.info = info;
-		err = notifier_call_chain(&fb_notifier_list,
+		err = blocking_notifier_call_chain(&fb_notifier_list,
 					   FB_EVENT_NEW_MODELIST,
 					   &event);
 	}
@@ -1495,7 +1498,7 @@ int fb_con_duit(struct fb_info *info, int event, void *data)
 	evnt.info = info;
 	evnt.data = data;
 
-	return notifier_call_chain(&fb_notifier_list, event, &evnt);
+	return blocking_notifier_call_chain(&fb_notifier_list, event, &evnt);
 }
 EXPORT_SYMBOL(fb_con_duit);
 

include/asm-i386/kdebug.h

@@ -17,11 +17,9 @@ struct die_args {
 	int signr;
 };
 
-/* Note - you should never unregister because that can race with NMIs.
-   If you really want to do it first unregister - then synchronize_sched - then free.
-  */
-int register_die_notifier(struct notifier_block *nb);
-extern struct notifier_block *i386die_chain;
+extern int register_die_notifier(struct notifier_block *);
+extern int unregister_die_notifier(struct notifier_block *);
+extern struct atomic_notifier_head i386die_chain;
 
 
 /* Grossly misnamed. */
@@ -51,7 +49,7 @@ static inline int notify_die(enum die_val val, const char *str,
 		.trapnr = trap,
 		.signr = sig
 	};
-	return notifier_call_chain(&i386die_chain, val, &args);
+	return atomic_notifier_call_chain(&i386die_chain, val, &args);
 }
 
 #endif

include/asm-ia64/kdebug.h

@@ -40,7 +40,7 @@ struct die_args {
 
 extern int register_die_notifier(struct notifier_block *);
 extern int unregister_die_notifier(struct notifier_block *);
-extern struct notifier_block *ia64die_chain;
+extern struct atomic_notifier_head ia64die_chain;
 
 enum die_val {
 	DIE_BREAK = 1,
@@ -81,7 +81,7 @@ static inline int notify_die(enum die_val val, char *str, struct pt_regs *regs,
 		.signr  = sig
 	};
 
-	return notifier_call_chain(&ia64die_chain, val, &args);
+	return atomic_notifier_call_chain(&ia64die_chain, val, &args);
 }
 
 #endif

include/asm-powerpc/kdebug.h

@@ -16,13 +16,9 @@ struct die_args {
 	int signr;
 };
 
-/*
-   Note - you should never unregister because that can race with NMIs.
-   If you really want to do it first unregister - then synchronize_sched -
-   then free.
- */
-int register_die_notifier(struct notifier_block *nb);
-extern struct notifier_block *powerpc_die_chain;
+extern int register_die_notifier(struct notifier_block *);
+extern int unregister_die_notifier(struct notifier_block *);
+extern struct atomic_notifier_head powerpc_die_chain;
 
 /* Grossly misnamed. */
 enum die_val {
@@ -37,7 +33,7 @@ enum die_val {
 static inline int notify_die(enum die_val val,char *str,struct pt_regs *regs,long err,int trap, int sig)
 {
 	struct die_args args = { .regs=regs, .str=str, .err=err, .trapnr=trap,.signr=sig };
-	return notifier_call_chain(&powerpc_die_chain, val, &args);
+	return atomic_notifier_call_chain(&powerpc_die_chain, val, &args);
 }
 
 #endif /* __KERNEL__ */

include/asm-sparc64/kdebug.h

@@ -15,12 +15,9 @@ struct die_args {
 	int signr;
 };
 
-/* Note - you should never unregister because that can race with NMIs.
- * If you really want to do it first unregister - then synchronize_sched
- * - then free.
- */
-int register_die_notifier(struct notifier_block *nb);
-extern struct notifier_block *sparc64die_chain;
+extern int register_die_notifier(struct notifier_block *);
+extern int unregister_die_notifier(struct notifier_block *);
+extern struct atomic_notifier_head sparc64die_chain;
 
 extern void bad_trap(struct pt_regs *, long);
 
@@ -46,7 +43,7 @@ static inline int notify_die(enum die_val val,char *str, struct pt_regs *regs,
 				 .trapnr	= trap,
 				 .signr		= sig };
 
-	return notifier_call_chain(&sparc64die_chain, val, &args);
+	return atomic_notifier_call_chain(&sparc64die_chain, val, &args);
 }
 
 #endif

include/asm-x86_64/kdebug.h

@@ -5,21 +5,20 @@
 
 struct pt_regs;
 
-struct die_args { 
+struct die_args {
 	struct pt_regs *regs;
 	const char *str;
-	long err; 
+	long err;
 	int trapnr;
 	int signr;
-}; 
+};
+
+extern int register_die_notifier(struct notifier_block *);
+extern int unregister_die_notifier(struct notifier_block *);
+extern struct atomic_notifier_head die_chain;
 
-/* Note - you should never unregister because that can race with NMIs.
-   If you really want to do it first unregister - then synchronize_sched - then free.
-  */
-int register_die_notifier(struct notifier_block *nb);
-extern struct notifier_block *die_chain;
 /* Grossly misnamed. */
-enum die_val { 
+enum die_val {
 	DIE_OOPS = 1,
 	DIE_INT3,
 	DIE_DEBUG,
@@ -33,8 +32,8 @@ enum die_val {
 	DIE_CALL,
 	DIE_NMI_IPI,
 	DIE_PAGE_FAULT,
-}; 
-	
+};
+
 static inline int notify_die(enum die_val val, const char *str,
 			struct pt_regs *regs, long err, int trap, int sig)
 {
@@ -45,7 +44,7 @@ static inline int notify_die(enum die_val val, const char *str,
 		.trapnr = trap,
 		.signr = sig
 	};
-	return notifier_call_chain(&die_chain, val, &args); 
+	return atomic_notifier_call_chain(&die_chain, val, &args);
 } 
 
 extern int printk_address(unsigned long address);

include/linux/adb.h

@@ -85,7 +85,7 @@ enum adb_message {
     ADB_MSG_POST_RESET	/* Called after resetting the bus (re-do init & register) */
 };
 extern struct adb_driver *adb_controller;
-extern struct notifier_block *adb_client_list;
+extern struct blocking_notifier_head adb_client_list;
 
 int adb_request(struct adb_request *req, void (*done)(struct adb_request *),
 		int flags, int nbytes, ...);

include/linux/kernel.h

@@ -87,7 +87,7 @@ extern int cond_resched(void);
 		(__x < 0) ? -__x : __x;		\
 	})
 
-extern struct notifier_block *panic_notifier_list;
+extern struct atomic_notifier_head panic_notifier_list;
 extern long (*panic_blink)(long time);
 NORET_TYPE void panic(const char * fmt, ...)
 	__attribute__ ((NORET_AND format (printf, 1, 2)));

include/linux/memory.h

@@ -77,7 +77,6 @@ extern int remove_memory_block(unsigned long, struct mem_section *, int);
 
 #define CONFIG_MEM_BLOCK_SIZE	(PAGES_PER_SECTION<<PAGE_SHIFT)
 
-struct notifier_block;
 
 #endif /* CONFIG_MEMORY_HOTPLUG */
 

include/linux/netfilter_ipv4/ip_conntrack.h

@@ -308,29 +308,30 @@ DECLARE_PER_CPU(struct ip_conntrack_ecache, ip_conntrack_ecache);
 
 #define CONNTRACK_ECACHE(x)	(__get_cpu_var(ip_conntrack_ecache).x)
  
-extern struct notifier_block *ip_conntrack_chain;
-extern struct notifier_block *ip_conntrack_expect_chain;
+extern struct atomic_notifier_head ip_conntrack_chain;
+extern struct atomic_notifier_head ip_conntrack_expect_chain;
 
 static inline int ip_conntrack_register_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_register(&ip_conntrack_chain, nb);
+	return atomic_notifier_chain_register(&ip_conntrack_chain, nb);
 }
 
 static inline int ip_conntrack_unregister_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_unregister(&ip_conntrack_chain, nb);
+	return atomic_notifier_chain_unregister(&ip_conntrack_chain, nb);
 }
 
 static inline int 
 ip_conntrack_expect_register_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_register(&ip_conntrack_expect_chain, nb);
+	return atomic_notifier_chain_register(&ip_conntrack_expect_chain, nb);
 }
 
 static inline int
 ip_conntrack_expect_unregister_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_unregister(&ip_conntrack_expect_chain, nb);
+	return atomic_notifier_chain_unregister(&ip_conntrack_expect_chain,
+			nb);
 }
 
 extern void ip_ct_deliver_cached_events(const struct ip_conntrack *ct);
@@ -355,14 +356,14 @@ static inline void ip_conntrack_event(enum ip_conntrack_events event,
 				      struct ip_conntrack *ct)
 {
 	if (is_confirmed(ct) && !is_dying(ct))
-		notifier_call_chain(&ip_conntrack_chain, event, ct);
+		atomic_notifier_call_chain(&ip_conntrack_chain, event, ct);
 }
 
 static inline void 
 ip_conntrack_expect_event(enum ip_conntrack_expect_events event,
 			  struct ip_conntrack_expect *exp)
 {
-	notifier_call_chain(&ip_conntrack_expect_chain, event, exp);
+	atomic_notifier_call_chain(&ip_conntrack_expect_chain, event, exp);
 }
 #else /* CONFIG_IP_NF_CONNTRACK_EVENTS */
 static inline void ip_conntrack_event_cache(enum ip_conntrack_events event, 

include/linux/notifier.h

@@ -10,25 +10,107 @@
 #ifndef _LINUX_NOTIFIER_H
 #define _LINUX_NOTIFIER_H
 #include <linux/errno.h>
+#include <linux/mutex.h>
+#include <linux/rwsem.h>
 
-struct notifier_block
-{
-	int (*notifier_call)(struct notifier_block *self, unsigned long, void *);
+/*
+ * Notifier chains are of three types:
+ *
+ *	Atomic notifier chains: Chain callbacks run in interrupt/atomic
+ *		context. Callouts are not allowed to block.
+ *	Blocking notifier chains: Chain callbacks run in process context.
+ *		Callouts are allowed to block.
+ *	Raw notifier chains: There are no restrictions on callbacks,
+ *		registration, or unregistration.  All locking and protection
+ *		must be provided by the caller.
+ *
+ * atomic_notifier_chain_register() may be called from an atomic context,
+ * but blocking_notifier_chain_register() must be called from a process
+ * context.  Ditto for the corresponding _unregister() routines.
+ *
+ * atomic_notifier_chain_unregister() and blocking_notifier_chain_unregister()
+ * _must not_ be called from within the call chain.
+ */
+
+struct notifier_block {
+	int (*notifier_call)(struct notifier_block *, unsigned long, void *);
 	struct notifier_block *next;
 	int priority;
 };
 
+struct atomic_notifier_head {
+	spinlock_t lock;
+	struct notifier_block *head;
+};
+
+struct blocking_notifier_head {
+	struct rw_semaphore rwsem;
+	struct notifier_block *head;
+};
+
+struct raw_notifier_head {
+	struct notifier_block *head;
+};
+
+#define ATOMIC_INIT_NOTIFIER_HEAD(name) do {	\
+		spin_lock_init(&(name)->lock);	\
+		(name)->head = NULL;		\
+	} while (0)
+#define BLOCKING_INIT_NOTIFIER_HEAD(name) do {	\
+		init_rwsem(&(name)->rwsem);	\
+		(name)->head = NULL;		\
+	} while (0)
+#define RAW_INIT_NOTIFIER_HEAD(name) do {	\
+		(name)->head = NULL;		\
+	} while (0)
+
+#define ATOMIC_NOTIFIER_INIT(name) {				\
+		.lock = SPIN_LOCK_UNLOCKED,			\
+		.head = NULL }
+#define BLOCKING_NOTIFIER_INIT(name) {				\
+		.rwsem = __RWSEM_INITIALIZER((name).rwsem),	\
+		.head = NULL }
+#define RAW_NOTIFIER_INIT(name)	{				\
+		.head = NULL }
+
+#define ATOMIC_NOTIFIER_HEAD(name)				\
+	struct atomic_notifier_head name =			\
+		ATOMIC_NOTIFIER_INIT(name)
+#define BLOCKING_NOTIFIER_HEAD(name)				\
+	struct blocking_notifier_head name =			\
+		BLOCKING_NOTIFIER_INIT(name)
+#define RAW_NOTIFIER_HEAD(name)					\
+	struct raw_notifier_head name =				\
+		RAW_NOTIFIER_INIT(name)
 
 #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 int notifier_call_chain(struct notifier_block **n, unsigned long val, void *v);
+extern int atomic_notifier_chain_register(struct atomic_notifier_head *,
+		struct notifier_block *);
+extern int blocking_notifier_chain_register(struct blocking_notifier_head *,
+		struct notifier_block *);
+extern int raw_notifier_chain_register(struct raw_notifier_head *,
+		struct notifier_block *);
+
+extern int atomic_notifier_chain_unregister(struct atomic_notifier_head *,
+		struct notifier_block *);
+extern int blocking_notifier_chain_unregister(struct blocking_notifier_head *,
+		struct notifier_block *);
+extern int raw_notifier_chain_unregister(struct raw_notifier_head *,
+		struct notifier_block *);
+
+extern int atomic_notifier_call_chain(struct atomic_notifier_head *,
+		unsigned long val, void *v);
+extern int blocking_notifier_call_chain(struct blocking_notifier_head *,
+		unsigned long val, void *v);
+extern int raw_notifier_call_chain(struct raw_notifier_head *,
+		unsigned long val, void *v);
 
 #define NOTIFY_DONE		0x0000		/* Don't care */
 #define NOTIFY_OK		0x0001		/* Suits me */
 #define NOTIFY_STOP_MASK	0x8000		/* Don't call further */
-#define NOTIFY_BAD		(NOTIFY_STOP_MASK|0x0002)	/* Bad/Veto action	*/
+#define NOTIFY_BAD		(NOTIFY_STOP_MASK|0x0002)
+						/* Bad/Veto action */
 /*
  * Clean way to return from the notifier and stop further calls.
  */

include/net/netfilter/nf_conntrack.h

@@ -300,29 +300,30 @@ DECLARE_PER_CPU(struct nf_conntrack_ecache, nf_conntrack_ecache);
 
 #define CONNTRACK_ECACHE(x)	(__get_cpu_var(nf_conntrack_ecache).x)
 
-extern struct notifier_block *nf_conntrack_chain;
-extern struct notifier_block *nf_conntrack_expect_chain;
+extern struct atomic_notifier_head nf_conntrack_chain;
+extern struct atomic_notifier_head nf_conntrack_expect_chain;
 
 static inline int nf_conntrack_register_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_register(&nf_conntrack_chain, nb);
+	return atomic_notifier_chain_register(&nf_conntrack_chain, nb);
 }
 
 static inline int nf_conntrack_unregister_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_unregister(&nf_conntrack_chain, nb);
+	return atomic_notifier_chain_unregister(&nf_conntrack_chain, nb);
 }
 
 static inline int
 nf_conntrack_expect_register_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_register(&nf_conntrack_expect_chain, nb);
+	return atomic_notifier_chain_register(&nf_conntrack_expect_chain, nb);
 }
 
 static inline int
 nf_conntrack_expect_unregister_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_unregister(&nf_conntrack_expect_chain, nb);
+	return atomic_notifier_chain_unregister(&nf_conntrack_expect_chain,
+			nb);
 }
 
 extern void nf_ct_deliver_cached_events(const struct nf_conn *ct);
@@ -347,14 +348,14 @@ static inline void nf_conntrack_event(enum ip_conntrack_events event,
 				      struct nf_conn *ct)
 {
 	if (nf_ct_is_confirmed(ct) && !nf_ct_is_dying(ct))
-		notifier_call_chain(&nf_conntrack_chain, event, ct);
+		atomic_notifier_call_chain(&nf_conntrack_chain, event, ct);
 }
 
 static inline void
 nf_conntrack_expect_event(enum ip_conntrack_expect_events event,
 			  struct nf_conntrack_expect *exp)
 {
-	notifier_call_chain(&nf_conntrack_expect_chain, event, exp);
+	atomic_notifier_call_chain(&nf_conntrack_expect_chain, event, exp);
 }
 #else /* CONFIG_NF_CONNTRACK_EVENTS */
 static inline void nf_conntrack_event_cache(enum ip_conntrack_events event,

kernel/cpu.c

@@ -18,7 +18,7 @@
 /* This protects CPUs going up and down... */
 static DECLARE_MUTEX(cpucontrol);
 
-static struct notifier_block *cpu_chain;
+static BLOCKING_NOTIFIER_HEAD(cpu_chain);
 
 #ifdef CONFIG_HOTPLUG_CPU
 static struct task_struct *lock_cpu_hotplug_owner;
@@ -71,21 +71,13 @@ EXPORT_SYMBOL_GPL(lock_cpu_hotplug_interruptible);
 /* Need to know about CPUs going up/down? */
 int register_cpu_notifier(struct notifier_block *nb)
 {
-	int ret;
-
-	if ((ret = lock_cpu_hotplug_interruptible()) != 0)
-		return ret;
-	ret = notifier_chain_register(&cpu_chain, nb);
-	unlock_cpu_hotplug();
-	return ret;
+	return blocking_notifier_chain_register(&cpu_chain, nb);
 }
 EXPORT_SYMBOL(register_cpu_notifier);
 
 void unregister_cpu_notifier(struct notifier_block *nb)
 {
-	lock_cpu_hotplug();
-	notifier_chain_unregister(&cpu_chain, nb);
-	unlock_cpu_hotplug();
+	blocking_notifier_chain_unregister(&cpu_chain, nb);
 }
 EXPORT_SYMBOL(unregister_cpu_notifier);
 
@@ -141,7 +133,7 @@ int cpu_down(unsigned int cpu)
 		goto out;
 	}
 
-	err = notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
+	err = blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE,
 						(void *)(long)cpu);
 	if (err == NOTIFY_BAD) {
 		printk("%s: attempt to take down CPU %u failed\n",
@@ -159,7 +151,7 @@ int cpu_down(unsigned int cpu)
 	p = __stop_machine_run(take_cpu_down, NULL, cpu);
 	if (IS_ERR(p)) {
 		/* CPU didn't die: tell everyone.  Can't complain. */
-		if (notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
+		if (blocking_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED,
 				(void *)(long)cpu) == NOTIFY_BAD)
 			BUG();
 
@@ -182,8 +174,8 @@ int cpu_down(unsigned int cpu)
 	put_cpu();
 
 	/* CPU is completely dead: tell everyone.  Too late to complain. */
-	if (notifier_call_chain(&cpu_chain, CPU_DEAD, (void *)(long)cpu)
-	    == NOTIFY_BAD)
+	if (blocking_notifier_call_chain(&cpu_chain, CPU_DEAD,
+			(void *)(long)cpu) == NOTIFY_BAD)
 		BUG();
 
 	check_for_tasks(cpu);
@@ -211,7 +203,7 @@ int __devinit cpu_up(unsigned int cpu)
 		goto out;
 	}
 
-	ret = notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);
+	ret = blocking_notifier_call_chain(&cpu_chain, CPU_UP_PREPARE, hcpu);
 	if (ret == NOTIFY_BAD) {
 		printk("%s: attempt to bring up CPU %u failed\n",
 				__FUNCTION__, cpu);
@@ -226,11 +218,12 @@ int __devinit cpu_up(unsigned int cpu)
 	BUG_ON(!cpu_online(cpu));
 
 	/* Now call notifier in preparation. */
-	notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
+	blocking_notifier_call_chain(&cpu_chain, CPU_ONLINE, hcpu);
 
 out_notify:
 	if (ret != 0)
-		notifier_call_chain(&cpu_chain, CPU_UP_CANCELED, hcpu);
+		blocking_notifier_call_chain(&cpu_chain,
+				CPU_UP_CANCELED, hcpu);
 out:
 	unlock_cpu_hotplug();
 	return ret;

kernel/module.c

@@ -64,26 +64,17 @@ static DEFINE_SPINLOCK(modlist_lock);
 static DEFINE_MUTEX(module_mutex);
 static LIST_HEAD(modules);
 
-static DEFINE_MUTEX(notify_mutex);
-static struct notifier_block * module_notify_list;
+static BLOCKING_NOTIFIER_HEAD(module_notify_list);
 
 int register_module_notifier(struct notifier_block * nb)
 {
-	int err;
-	mutex_lock(&notify_mutex);
-	err = notifier_chain_register(&module_notify_list, nb);
-	mutex_unlock(&notify_mutex);
-	return err;
+	return blocking_notifier_chain_register(&module_notify_list, nb);
 }
 EXPORT_SYMBOL(register_module_notifier);
 
 int unregister_module_notifier(struct notifier_block * nb)
 {
-	int err;
-	mutex_lock(&notify_mutex);
-	err = notifier_chain_unregister(&module_notify_list, nb);
-	mutex_unlock(&notify_mutex);
-	return err;
+	return blocking_notifier_chain_unregister(&module_notify_list, nb);
 }
 EXPORT_SYMBOL(unregister_module_notifier);
 
@@ -1816,9 +1807,8 @@ sys_init_module(void __user *umod,
 	/* Drop lock so they can recurse */
 	mutex_unlock(&module_mutex);
 
-	mutex_lock(&notify_mutex);
-	notifier_call_chain(&module_notify_list, MODULE_STATE_COMING, mod);
-	mutex_unlock(&notify_mutex);
+	blocking_notifier_call_chain(&module_notify_list,
+			MODULE_STATE_COMING, mod);
 
 	/* Start the module */
 	if (mod->init != NULL)

kernel/panic.c

@@ -29,7 +29,7 @@ static DEFINE_SPINLOCK(pause_on_oops_lock);
 int panic_timeout;
 EXPORT_SYMBOL(panic_timeout);
 
-struct notifier_block *panic_notifier_list;
+ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
 
 EXPORT_SYMBOL(panic_notifier_list);
 
@@ -97,7 +97,7 @@ NORET_TYPE void panic(const char * fmt, ...)
 	smp_send_stop();
 #endif
 
-	notifier_call_chain(&panic_notifier_list, 0, buf);
+	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
 
 	if (!panic_blink)
 		panic_blink = no_blink;

kernel/profile.c

@@ -87,72 +87,52 @@ void __init profile_init(void)
  
 #ifdef CONFIG_PROFILING
  
-static DECLARE_RWSEM(profile_rwsem);
-static DEFINE_RWLOCK(handoff_lock);
-static struct notifier_block * task_exit_notifier;
-static struct notifier_block * task_free_notifier;
-static struct notifier_block * munmap_notifier;
+static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
+static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
+static BLOCKING_NOTIFIER_HEAD(munmap_notifier);
  
 void profile_task_exit(struct task_struct * task)
 {
-	down_read(&profile_rwsem);
-	notifier_call_chain(&task_exit_notifier, 0, task);
-	up_read(&profile_rwsem);
+	blocking_notifier_call_chain(&task_exit_notifier, 0, task);
 }
  
 int profile_handoff_task(struct task_struct * task)
 {
 	int ret;
-	read_lock(&handoff_lock);
-	ret = notifier_call_chain(&task_free_notifier, 0, task);
-	read_unlock(&handoff_lock);
+	ret = atomic_notifier_call_chain(&task_free_notifier, 0, task);
 	return (ret == NOTIFY_OK) ? 1 : 0;
 }
 
 void profile_munmap(unsigned long addr)
 {
-	down_read(&profile_rwsem);
-	notifier_call_chain(&munmap_notifier, 0, (void *)addr);
-	up_read(&profile_rwsem);
+	blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);
 }
 
 int task_handoff_register(struct notifier_block * n)
 {
-	int err = -EINVAL;
-
-	write_lock(&handoff_lock);
-	err = notifier_chain_register(&task_free_notifier, n);
-	write_unlock(&handoff_lock);
-	return err;
+	return atomic_notifier_chain_register(&task_free_notifier, n);
 }
 
 int task_handoff_unregister(struct notifier_block * n)
 {
-	int err = -EINVAL;
-
-	write_lock(&handoff_lock);
-	err = notifier_chain_unregister(&task_free_notifier, n);
-	write_unlock(&handoff_lock);
-	return err;
+	return atomic_notifier_chain_unregister(&task_free_notifier, n);
 }
 
 int profile_event_register(enum profile_type type, struct notifier_block * n)
 {
 	int err = -EINVAL;
  
-	down_write(&profile_rwsem);
- 
 	switch (type) {
 		case PROFILE_TASK_EXIT:
-			err = notifier_chain_register(&task_exit_notifier, n);
+			err = blocking_notifier_chain_register(
+					&task_exit_notifier, n);
 			break;
 		case PROFILE_MUNMAP:
-			err = notifier_chain_register(&munmap_notifier, n);
+			err = blocking_notifier_chain_register(
+					&munmap_notifier, n);
 			break;
 	}
  
-	up_write(&profile_rwsem);
- 
 	return err;
 }
 
@@ -161,18 +141,17 @@ int 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);
+			err = blocking_notifier_chain_unregister(
+					&task_exit_notifier, n);
 			break;
 		case PROFILE_MUNMAP:
-			err = notifier_chain_unregister(&munmap_notifier, n);
+			err = blocking_notifier_chain_unregister(
+					&munmap_notifier, n);
 			break;
 	}
 
-	up_write(&profile_rwsem);
 	return err;
 }
 

kernel/softlockup.c

@@ -152,5 +152,5 @@ __init void spawn_softlockup_task(void)
 	cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
 	register_cpu_notifier(&cpu_nfb);
 
-	notifier_chain_register(&panic_notifier_list, &panic_block);
+	atomic_notifier_chain_register(&panic_notifier_list, &panic_block);
 }

kernel/sys.c

@@ -95,99 +95,304 @@ int cad_pid = 1;
  *	and the like. 
  */
 
-static struct notifier_block *reboot_notifier_list;
-static DEFINE_RWLOCK(notifier_lock);
+static BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);
+
+/*
+ *	Notifier chain core routines.  The exported routines below
+ *	are layered on top of these, with appropriate locking added.
+ */
+
+static int notifier_chain_register(struct notifier_block **nl,
+		struct notifier_block *n)
+{
+	while ((*nl) != NULL) {
+		if (n->priority > (*nl)->priority)
+			break;
+		nl = &((*nl)->next);
+	}
+	n->next = *nl;
+	rcu_assign_pointer(*nl, n);
+	return 0;
+}
+
+static int notifier_chain_unregister(struct notifier_block **nl,
+		struct notifier_block *n)
+{
+	while ((*nl) != NULL) {
+		if ((*nl) == n) {
+			rcu_assign_pointer(*nl, n->next);
+			return 0;
+		}
+		nl = &((*nl)->next);
+	}
+	return -ENOENT;
+}
+
+static int __kprobes notifier_call_chain(struct notifier_block **nl,
+		unsigned long val, void *v)
+{
+	int ret = NOTIFY_DONE;
+	struct notifier_block *nb;
+
+	nb = rcu_dereference(*nl);
+	while (nb) {
+		ret = nb->notifier_call(nb, val, v);
+		if ((ret & NOTIFY_STOP_MASK) == NOTIFY_STOP_MASK)
+			break;
+		nb = rcu_dereference(nb->next);
+	}
+	return ret;
+}
+
+/*
+ *	Atomic notifier chain routines.  Registration and unregistration
+ *	use a mutex, and call_chain is synchronized by RCU (no locks).
+ */
 
 /**
- *	notifier_chain_register	- Add notifier to a notifier chain
- *	@list: Pointer to root list pointer
+ *	atomic_notifier_chain_register - Add notifier to an atomic notifier chain
+ *	@nh: Pointer to head of the atomic notifier chain
  *	@n: New entry in notifier chain
  *
- *	Adds a notifier to a notifier chain.
+ *	Adds a notifier to an atomic notifier chain.
  *
  *	Currently always returns zero.
  */
+
+int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
+		struct notifier_block *n)
+{
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&nh->lock, flags);
+	ret = notifier_chain_register(&nh->head, n);
+	spin_unlock_irqrestore(&nh->lock, flags);
+	return ret;
+}
+
+EXPORT_SYMBOL_GPL(atomic_notifier_chain_register);
+
+/**
+ *	atomic_notifier_chain_unregister - Remove notifier from an atomic notifier chain
+ *	@nh: Pointer to head of the atomic notifier chain
+ *	@n: Entry to remove from notifier chain
+ *
+ *	Removes a notifier from an atomic notifier chain.
+ *
+ *	Returns zero on success or %-ENOENT on failure.
+ */
+int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
+		struct notifier_block *n)
+{
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&nh->lock, flags);
+	ret = notifier_chain_unregister(&nh->head, n);
+	spin_unlock_irqrestore(&nh->lock, flags);
+	synchronize_rcu();
+	return ret;
+}
+
+EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister);
+
+/**
+ *	atomic_notifier_call_chain - Call functions in an atomic notifier chain
+ *	@nh: Pointer to head of the atomic notifier chain
+ *	@val: Value passed unmodified to notifier function
+ *	@v: Pointer passed unmodified to notifier function
+ *
+ *	Calls each function in a notifier chain in turn.  The functions
+ *	run in an atomic context, so they must not block.
+ *	This routine uses RCU to synchronize with changes to the chain.
+ *
+ *	If the return value of the notifier can be and'ed
+ *	with %NOTIFY_STOP_MASK then atomic_notifier_call_chain
+ *	will return immediately, with the return value of
+ *	the notifier function which halted execution.
+ *	Otherwise the return value is the return value
+ *	of the last notifier function called.
+ */
  
-int notifier_chain_register(struct notifier_block **list, struct notifier_block *n)
+int atomic_notifier_call_chain(struct atomic_notifier_head *nh,
+		unsigned long val, void *v)
 {
-	write_lock(&notifier_lock);
-	while(*list)
-	{
-		if(n->priority > (*list)->priority)
-			break;
-		list= &((*list)->next);
-	}
-	n->next = *list;
-	*list=n;
-	write_unlock(&notifier_lock);
-	return 0;
+	int ret;
+
+	rcu_read_lock();
+	ret = notifier_call_chain(&nh->head, val, v);
+	rcu_read_unlock();
+	return ret;
 }
 
-EXPORT_SYMBOL(notifier_chain_register);
+EXPORT_SYMBOL_GPL(atomic_notifier_call_chain);
+
+/*
+ *	Blocking notifier chain routines.  All access to the chain is
+ *	synchronized by an rwsem.
+ */
 
 /**
- *	notifier_chain_unregister - Remove notifier from a notifier chain
- *	@nl: Pointer to root list pointer
+ *	blocking_notifier_chain_register - Add notifier to a blocking notifier chain
+ *	@nh: Pointer to head of the blocking notifier chain
  *	@n: New entry in notifier chain
  *
- *	Removes a notifier from a notifier chain.
+ *	Adds a notifier to a blocking notifier chain.
+ *	Must be called in process context.
  *
- *	Returns zero on success, or %-ENOENT on failure.
+ *	Currently always returns zero.
  */
  
-int notifier_chain_unregister(struct notifier_block **nl, struct notifier_block *n)
+int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
+		struct notifier_block *n)
 {
-	write_lock(&notifier_lock);
-	while((*nl)!=NULL)
-	{
-		if((*nl)==n)
-		{
-			*nl=n->next;
-			write_unlock(&notifier_lock);
-			return 0;
-		}
-		nl=&((*nl)->next);
-	}
-	write_unlock(&notifier_lock);
-	return -ENOENT;
+	int ret;
+
+	/*
+	 * This code gets used during boot-up, when task switching is
+	 * not yet working and interrupts must remain disabled.  At
+	 * such times we must not call down_write().
+	 */
+	if (unlikely(system_state == SYSTEM_BOOTING))
+		return notifier_chain_register(&nh->head, n);
+
+	down_write(&nh->rwsem);
+	ret = notifier_chain_register(&nh->head, n);
+	up_write(&nh->rwsem);
+	return ret;
 }
 
-EXPORT_SYMBOL(notifier_chain_unregister);
+EXPORT_SYMBOL_GPL(blocking_notifier_chain_register);
 
 /**
- *	notifier_call_chain - Call functions in a notifier chain
- *	@n: Pointer to root pointer of notifier chain
+ *	blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain
+ *	@nh: Pointer to head of the blocking notifier chain
+ *	@n: Entry to remove from notifier chain
+ *
+ *	Removes a notifier from a blocking notifier chain.
+ *	Must be called from process context.
+ *
+ *	Returns zero on success or %-ENOENT on failure.
+ */
+int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh,
+		struct notifier_block *n)
+{
+	int ret;
+
+	/*
+	 * This code gets used during boot-up, when task switching is
+	 * not yet working and interrupts must remain disabled.  At
+	 * such times we must not call down_write().
+	 */
+	if (unlikely(system_state == SYSTEM_BOOTING))
+		return notifier_chain_unregister(&nh->head, n);
+
+	down_write(&nh->rwsem);
+	ret = notifier_chain_unregister(&nh->head, n);
+	up_write(&nh->rwsem);
+	return ret;
+}
+
+EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister);
+
+/**
+ *	blocking_notifier_call_chain - Call functions in a blocking notifier chain
+ *	@nh: Pointer to head of the blocking notifier chain
  *	@val: Value passed unmodified to notifier function
  *	@v: Pointer passed unmodified to notifier function
  *
- *	Calls each function in a notifier chain in turn.
+ *	Calls each function in a notifier chain in turn.  The functions
+ *	run in a process context, so they are allowed to block.
  *
- *	If the return value of the notifier can be and'd
- *	with %NOTIFY_STOP_MASK, then notifier_call_chain
+ *	If the return value of the notifier can be and'ed
+ *	with %NOTIFY_STOP_MASK then blocking_notifier_call_chain
  *	will return immediately, with the return value of
  *	the notifier function which halted execution.
- *	Otherwise, the return value is the return value
+ *	Otherwise the return value is the return value
  *	of the last notifier function called.
  */
  
-int __kprobes notifier_call_chain(struct notifier_block **n, unsigned long val, void *v)
+int blocking_notifier_call_chain(struct blocking_notifier_head *nh,
+		unsigned long val, void *v)
 {
-	int ret=NOTIFY_DONE;
-	struct notifier_block *nb = *n;
+	int ret;
 
-	while(nb)
-	{
-		ret=nb->notifier_call(nb,val,v);
-		if(ret&NOTIFY_STOP_MASK)
-		{
-			return ret;
-		}
-		nb=nb->next;
-	}
+	down_read(&nh->rwsem);
+	ret = notifier_call_chain(&nh->head, val, v);
+	up_read(&nh->rwsem);
 	return ret;
 }
 
-EXPORT_SYMBOL(notifier_call_chain);
+EXPORT_SYMBOL_GPL(blocking_notifier_call_chain);
+
+/*
+ *	Raw notifier chain routines.  There is no protection;
+ *	the caller must provide it.  Use at your own risk!
+ */
+
+/**
+ *	raw_notifier_chain_register - Add notifier to a raw notifier chain
+ *	@nh: Pointer to head of the raw notifier chain
+ *	@n: New entry in notifier chain
+ *
+ *	Adds a notifier to a raw notifier chain.
+ *	All locking must be provided by the caller.
+ *
+ *	Currently always returns zero.
+ */
+
+int raw_notifier_chain_register(struct raw_notifier_head *nh,
+		struct notifier_block *n)
+{
+	return notifier_chain_register(&nh->head, n);
+}
+
+EXPORT_SYMBOL_GPL(raw_notifier_chain_register);
+
+/**
+ *	raw_notifier_chain_unregister - Remove notifier from a raw notifier chain
+ *	@nh: Pointer to head of the raw notifier chain
+ *	@n: Entry to remove from notifier chain
+ *
+ *	Removes a notifier from a raw notifier chain.
+ *	All locking must be provided by the caller.
+ *
+ *	Returns zero on success or %-ENOENT on failure.
+ */
+int raw_notifier_chain_unregister(struct raw_notifier_head *nh,
+		struct notifier_block *n)
+{
+	return notifier_chain_unregister(&nh->head, n);
+}
+
+EXPORT_SYMBOL_GPL(raw_notifier_chain_unregister);
+
+/**
+ *	raw_notifier_call_chain - Call functions in a raw notifier chain
+ *	@nh: Pointer to head of the raw notifier chain
+ *	@val: Value passed unmodified to notifier function
+ *	@v: Pointer passed unmodified to notifier function
+ *
+ *	Calls each function in a notifier chain in turn.  The functions
+ *	run in an undefined context.
+ *	All locking must be provided by the caller.
+ *
+ *	If the return value of the notifier can be and'ed
+ *	with %NOTIFY_STOP_MASK then raw_notifier_call_chain
+ *	will return immediately, with the return value of
+ *	the notifier function which halted execution.
+ *	Otherwise the return value is the return value
+ *	of the last notifier function called.
+ */
+
+int raw_notifier_call_chain(struct raw_notifier_head *nh,
+		unsigned long val, void *v)
+{
+	return notifier_call_chain(&nh->head, val, v);
+}
+
+EXPORT_SYMBOL_GPL(raw_notifier_call_chain);
 
 /**
  *	register_reboot_notifier - Register function to be called at reboot time
@@ -196,13 +401,13 @@ EXPORT_SYMBOL(notifier_call_chain);
  *	Registers a function with the list of functions
  *	to be called at reboot time.
  *
- *	Currently always returns zero, as notifier_chain_register
+ *	Currently always returns zero, as blocking_notifier_chain_register
  *	always returns zero.
  */
  
 int register_reboot_notifier(struct notifier_block * nb)
 {
-	return notifier_chain_register(&reboot_notifier_list, nb);
+	return blocking_notifier_chain_register(&reboot_notifier_list, nb);
 }
 
 EXPORT_SYMBOL(register_reboot_notifier);
@@ -219,7 +424,7 @@ EXPORT_SYMBOL(register_reboot_notifier);
  
 int unregister_reboot_notifier(struct notifier_block * nb)
 {
-	return notifier_chain_unregister(&reboot_notifier_list, nb);
+	return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
 }
 
 EXPORT_SYMBOL(unregister_reboot_notifier);
@@ -380,7 +585,7 @@ EXPORT_SYMBOL_GPL(emergency_restart);
 
 void kernel_restart_prepare(char *cmd)
 {
-	notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
+	blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
 	system_state = SYSTEM_RESTART;
 	device_shutdown();
 }
@@ -430,7 +635,7 @@ EXPORT_SYMBOL_GPL(kernel_kexec);
 
 void kernel_shutdown_prepare(enum system_states state)
 {
-	notifier_call_chain(&reboot_notifier_list,
+	blocking_notifier_call_chain(&reboot_notifier_list,
 		(state == SYSTEM_HALT)?SYS_HALT:SYS_POWER_OFF, NULL);
 	system_state = state;
 	device_shutdown();

net/bluetooth/hci_core.c

@@ -73,23 +73,23 @@ DEFINE_RWLOCK(hci_cb_list_lock);
 struct hci_proto *hci_proto[HCI_MAX_PROTO];
 
 /* HCI notifiers list */
-static struct notifier_block *hci_notifier;
+static ATOMIC_NOTIFIER_HEAD(hci_notifier);
 
 /* ---- HCI notifications ---- */
 
 int hci_register_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_register(&hci_notifier, nb);
+	return atomic_notifier_chain_register(&hci_notifier, nb);
 }
 
 int hci_unregister_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_unregister(&hci_notifier, nb);
+	return atomic_notifier_chain_unregister(&hci_notifier, nb);
 }
 
 static void hci_notify(struct hci_dev *hdev, int event)
 {
-	notifier_call_chain(&hci_notifier, event, hdev);
+	atomic_notifier_call_chain(&hci_notifier, event, hdev);
 }
 
 /* ---- HCI requests ---- */

net/core/dev.c

@@ -193,7 +193,7 @@ static inline struct hlist_head *dev_index_hash(int ifindex)
  *	Our notifier list
  */
 
-static struct notifier_block *netdev_chain;
+static BLOCKING_NOTIFIER_HEAD(netdev_chain);
 
 /*
  *	Device drivers call our routines to queue packets here. We empty the
@@ -736,7 +736,8 @@ int dev_change_name(struct net_device *dev, char *newname)
 	if (!err) {
 		hlist_del(&dev->name_hlist);
 		hlist_add_head(&dev->name_hlist, dev_name_hash(dev->name));
-		notifier_call_chain(&netdev_chain, NETDEV_CHANGENAME, dev);
+		blocking_notifier_call_chain(&netdev_chain,
+				NETDEV_CHANGENAME, dev);
 	}
 
 	return err;
@@ -750,7 +751,7 @@ int dev_change_name(struct net_device *dev, char *newname)
  */
 void netdev_features_change(struct net_device *dev)
 {
-	notifier_call_chain(&netdev_chain, NETDEV_FEAT_CHANGE, dev);
+	blocking_notifier_call_chain(&netdev_chain, NETDEV_FEAT_CHANGE, dev);
 }
 EXPORT_SYMBOL(netdev_features_change);
 
@@ -765,7 +766,8 @@ EXPORT_SYMBOL(netdev_features_change);
 void netdev_state_change(struct net_device *dev)
 {
 	if (dev->flags & IFF_UP) {
-		notifier_call_chain(&netdev_chain, NETDEV_CHANGE, dev);
+		blocking_notifier_call_chain(&netdev_chain,
+				NETDEV_CHANGE, dev);
 		rtmsg_ifinfo(RTM_NEWLINK, dev, 0);
 	}
 }
@@ -862,7 +864,7 @@ int dev_open(struct net_device *dev)
 		/*
 		 *	... and announce new interface.
 		 */
-		notifier_call_chain(&netdev_chain, NETDEV_UP, dev);
+		blocking_notifier_call_chain(&netdev_chain, NETDEV_UP, dev);
 	}
 	return ret;
 }
@@ -885,7 +887,7 @@ int dev_close(struct net_device *dev)
 	 *	Tell people we are going down, so that they can
 	 *	prepare to death, when device is still operating.
 	 */
-	notifier_call_chain(&netdev_chain, NETDEV_GOING_DOWN, dev);
+	blocking_notifier_call_chain(&netdev_chain, NETDEV_GOING_DOWN, dev);
 
 	dev_deactivate(dev);
 
@@ -922,7 +924,7 @@ int dev_close(struct net_device *dev)
 	/*
 	 * Tell people we are down
 	 */
-	notifier_call_chain(&netdev_chain, NETDEV_DOWN, dev);
+	blocking_notifier_call_chain(&netdev_chain, NETDEV_DOWN, dev);
 
 	return 0;
 }
@@ -953,7 +955,7 @@ int register_netdevice_notifier(struct notifier_block *nb)
 	int err;
 
 	rtnl_lock();
-	err = notifier_chain_register(&netdev_chain, nb);
+	err = blocking_notifier_chain_register(&netdev_chain, nb);
 	if (!err) {
 		for (dev = dev_base; dev; dev = dev->next) {
 			nb->notifier_call(nb, NETDEV_REGISTER, dev);
@@ -981,7 +983,7 @@ int unregister_netdevice_notifier(struct notifier_block *nb)
 	int err;
 
 	rtnl_lock();
-	err = notifier_chain_unregister(&netdev_chain, nb);
+	err = blocking_notifier_chain_unregister(&netdev_chain, nb);
 	rtnl_unlock();
 	return err;
 }
@@ -992,12 +994,12 @@ int unregister_netdevice_notifier(struct notifier_block *nb)
  *      @v:   pointer passed unmodified to notifier function
  *
  *	Call all network notifier blocks.  Parameters and return value
- *	are as for notifier_call_chain().
+ *	are as for blocking_notifier_call_chain().
  */
 
 int call_netdevice_notifiers(unsigned long val, void *v)
 {
-	return notifier_call_chain(&netdev_chain, val, v);
+	return blocking_notifier_call_chain(&netdev_chain, val, v);
 }
 
 /* When > 0 there are consumers of rx skb time stamps */
@@ -2242,7 +2244,8 @@ int dev_change_flags(struct net_device *dev, unsigned flags)
 	if (dev->flags & IFF_UP &&
 	    ((old_flags ^ dev->flags) &~ (IFF_UP | IFF_PROMISC | IFF_ALLMULTI |
 					  IFF_VOLATILE)))
-		notifier_call_chain(&netdev_chain, NETDEV_CHANGE, dev);
+		blocking_notifier_call_chain(&netdev_chain,
+				NETDEV_CHANGE, dev);
 
 	if ((flags ^ dev->gflags) & IFF_PROMISC) {
 		int inc = (flags & IFF_PROMISC) ? +1 : -1;
@@ -2286,8 +2289,8 @@ int dev_set_mtu(struct net_device *dev, int new_mtu)
 	else
 		dev->mtu = new_mtu;
 	if (!err && dev->flags & IFF_UP)
-		notifier_call_chain(&netdev_chain,
-				    NETDEV_CHANGEMTU, dev);
+		blocking_notifier_call_chain(&netdev_chain,
+				NETDEV_CHANGEMTU, dev);
 	return err;
 }
 
@@ -2303,7 +2306,8 @@ int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa)
 		return -ENODEV;
 	err = dev->set_mac_address(dev, sa);
 	if (!err)
-		notifier_call_chain(&netdev_chain, NETDEV_CHANGEADDR, dev);
+		blocking_notifier_call_chain(&netdev_chain,
+				NETDEV_CHANGEADDR, dev);
 	return err;
 }
 
@@ -2359,7 +2363,7 @@ static int dev_ifsioc(struct ifreq *ifr, unsigned int cmd)
 				return -EINVAL;
 			memcpy(dev->broadcast, ifr->ifr_hwaddr.sa_data,
 			       min(sizeof ifr->ifr_hwaddr.sa_data, (size_t) dev->addr_len));
-			notifier_call_chain(&netdev_chain,
+			blocking_notifier_call_chain(&netdev_chain,
 					    NETDEV_CHANGEADDR, dev);
 			return 0;
 
@@ -2813,7 +2817,7 @@ int register_netdevice(struct net_device *dev)
 	write_unlock_bh(&dev_base_lock);
 
 	/* Notify protocols, that a new device appeared. */
-	notifier_call_chain(&netdev_chain, NETDEV_REGISTER, dev);
+	blocking_notifier_call_chain(&netdev_chain, NETDEV_REGISTER, dev);
 
 	/* Finish registration after unlock */
 	net_set_todo(dev);
@@ -2892,7 +2896,7 @@ static void netdev_wait_allrefs(struct net_device *dev)
 			rtnl_lock();
 
 			/* Rebroadcast unregister notification */
-			notifier_call_chain(&netdev_chain,
+			blocking_notifier_call_chain(&netdev_chain,
 					    NETDEV_UNREGISTER, dev);
 
 			if (test_bit(__LINK_STATE_LINKWATCH_PENDING,
@@ -3148,7 +3152,7 @@ int unregister_netdevice(struct net_device *dev)
 	/* Notify protocols, that we are about to destroy
 	   this device. They should clean all the things.
 	*/
-	notifier_call_chain(&netdev_chain, NETDEV_UNREGISTER, dev);
+	blocking_notifier_call_chain(&netdev_chain, NETDEV_UNREGISTER, dev);
 	
 	/*
 	 *	Flush the multicast chain

net/decnet/dn_dev.c

@@ -68,7 +68,7 @@ __le16 decnet_address = 0;
 
 static DEFINE_RWLOCK(dndev_lock);
 static struct net_device *decnet_default_device;
-static struct notifier_block *dnaddr_chain;
+static BLOCKING_NOTIFIER_HEAD(dnaddr_chain);
 
 static struct dn_dev *dn_dev_create(struct net_device *dev, int *err);
 static void dn_dev_delete(struct net_device *dev);
@@ -446,7 +446,7 @@ static void dn_dev_del_ifa(struct dn_dev *dn_db, struct dn_ifaddr **ifap, int de
 	}
 
 	rtmsg_ifa(RTM_DELADDR, ifa1);
-	notifier_call_chain(&dnaddr_chain, NETDEV_DOWN, ifa1);
+	blocking_notifier_call_chain(&dnaddr_chain, NETDEV_DOWN, ifa1);
 	if (destroy) {
 		dn_dev_free_ifa(ifa1);
 
@@ -481,7 +481,7 @@ static int dn_dev_insert_ifa(struct dn_dev *dn_db, struct dn_ifaddr *ifa)
 	dn_db->ifa_list = ifa;
 
 	rtmsg_ifa(RTM_NEWADDR, ifa);
-	notifier_call_chain(&dnaddr_chain, NETDEV_UP, ifa);
+	blocking_notifier_call_chain(&dnaddr_chain, NETDEV_UP, ifa);
 
 	return 0;
 }
@@ -1285,12 +1285,12 @@ void dn_dev_devices_on(void)
 
 int register_dnaddr_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_register(&dnaddr_chain, nb);
+	return blocking_notifier_chain_register(&dnaddr_chain, nb);
 }
 
 int unregister_dnaddr_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_unregister(&dnaddr_chain, nb);
+	return blocking_notifier_chain_unregister(&dnaddr_chain, nb);
 }
 
 #ifdef CONFIG_PROC_FS

net/ipv4/devinet.c

@@ -81,7 +81,7 @@ static struct ipv4_devconf ipv4_devconf_dflt = {
 
 static void rtmsg_ifa(int event, struct in_ifaddr *);
 
-static struct notifier_block *inetaddr_chain;
+static BLOCKING_NOTIFIER_HEAD(inetaddr_chain);
 static void inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap,
 			 int destroy);
 #ifdef CONFIG_SYSCTL
@@ -267,7 +267,8 @@ static void inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap,
 				*ifap1 = ifa->ifa_next;
 
 				rtmsg_ifa(RTM_DELADDR, ifa);
-				notifier_call_chain(&inetaddr_chain, NETDEV_DOWN, ifa);
+				blocking_notifier_call_chain(&inetaddr_chain,
+						NETDEV_DOWN, ifa);
 				inet_free_ifa(ifa);
 			} else {
 				promote = ifa;
@@ -291,7 +292,7 @@ static void inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap,
 	   So that, this order is correct.
 	 */
 	rtmsg_ifa(RTM_DELADDR, ifa1);
-	notifier_call_chain(&inetaddr_chain, NETDEV_DOWN, ifa1);
+	blocking_notifier_call_chain(&inetaddr_chain, NETDEV_DOWN, ifa1);
 
 	if (promote) {
 
@@ -303,7 +304,8 @@ static void inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap,
 
 		promote->ifa_flags &= ~IFA_F_SECONDARY;
 		rtmsg_ifa(RTM_NEWADDR, promote);
-		notifier_call_chain(&inetaddr_chain, NETDEV_UP, promote);
+		blocking_notifier_call_chain(&inetaddr_chain,
+				NETDEV_UP, promote);
 		for (ifa = promote->ifa_next; ifa; ifa = ifa->ifa_next) {
 			if (ifa1->ifa_mask != ifa->ifa_mask ||
 			    !inet_ifa_match(ifa1->ifa_address, ifa))
@@ -366,7 +368,7 @@ static int inet_insert_ifa(struct in_ifaddr *ifa)
 	   Notifier will trigger FIB update, so that
 	   listeners of netlink will know about new ifaddr */
 	rtmsg_ifa(RTM_NEWADDR, ifa);
-	notifier_call_chain(&inetaddr_chain, NETDEV_UP, ifa);
+	blocking_notifier_call_chain(&inetaddr_chain, NETDEV_UP, ifa);
 
 	return 0;
 }
@@ -938,12 +940,12 @@ u32 inet_confirm_addr(const struct net_device *dev, u32 dst, u32 local, int scop
 
 int register_inetaddr_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_register(&inetaddr_chain, nb);
+	return blocking_notifier_chain_register(&inetaddr_chain, nb);
 }
 
 int unregister_inetaddr_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_unregister(&inetaddr_chain, nb);
+	return blocking_notifier_chain_unregister(&inetaddr_chain, nb);
 }
 
 /* Rename ifa_labels for a device name change. Make some effort to preserve existing

net/ipv4/netfilter/ip_conntrack_core.c

@@ -80,8 +80,8 @@ static int ip_conntrack_vmalloc;
 static unsigned int ip_conntrack_next_id;
 static unsigned int ip_conntrack_expect_next_id;
 #ifdef CONFIG_IP_NF_CONNTRACK_EVENTS
-struct notifier_block *ip_conntrack_chain;
-struct notifier_block *ip_conntrack_expect_chain;
+ATOMIC_NOTIFIER_HEAD(ip_conntrack_chain);
+ATOMIC_NOTIFIER_HEAD(ip_conntrack_expect_chain);
 
 DEFINE_PER_CPU(struct ip_conntrack_ecache, ip_conntrack_ecache);
 
@@ -92,7 +92,7 @@ __ip_ct_deliver_cached_events(struct ip_conntrack_ecache *ecache)
 {
 	DEBUGP("ecache: delivering events for %p\n", ecache->ct);
 	if (is_confirmed(ecache->ct) && !is_dying(ecache->ct) && ecache->events)
-		notifier_call_chain(&ip_conntrack_chain, ecache->events,
+		atomic_notifier_call_chain(&ip_conntrack_chain, ecache->events,
 				    ecache->ct);
 	ecache->events = 0;
 	ip_conntrack_put(ecache->ct);

net/ipv6/addrconf.c

@@ -143,7 +143,7 @@ static void inet6_prefix_notify(int event, struct inet6_dev *idev,
 				struct prefix_info *pinfo);
 static int ipv6_chk_same_addr(const struct in6_addr *addr, struct net_device *dev);
 
-static struct notifier_block *inet6addr_chain;
+static ATOMIC_NOTIFIER_HEAD(inet6addr_chain);
 
 struct ipv6_devconf ipv6_devconf = {
 	.forwarding		= 0,
@@ -593,7 +593,7 @@ out2:
 	read_unlock_bh(&addrconf_lock);
 
 	if (likely(err == 0))
-		notifier_call_chain(&inet6addr_chain, NETDEV_UP, ifa);
+		atomic_notifier_call_chain(&inet6addr_chain, NETDEV_UP, ifa);
 	else {
 		kfree(ifa);
 		ifa = ERR_PTR(err);
@@ -688,7 +688,7 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp)
 
 	ipv6_ifa_notify(RTM_DELADDR, ifp);
 
-	notifier_call_chain(&inet6addr_chain,NETDEV_DOWN,ifp);
+	atomic_notifier_call_chain(&inet6addr_chain, NETDEV_DOWN, ifp);
 
 	addrconf_del_timer(ifp);
 
@@ -3767,12 +3767,12 @@ static void addrconf_sysctl_unregister(struct ipv6_devconf *p)
 
 int register_inet6addr_notifier(struct notifier_block *nb)
 {
-        return notifier_chain_register(&inet6addr_chain, nb);
+        return atomic_notifier_chain_register(&inet6addr_chain, nb);
 }
 
 int unregister_inet6addr_notifier(struct notifier_block *nb)
 {
-        return notifier_chain_unregister(&inet6addr_chain,nb);
+        return atomic_notifier_chain_unregister(&inet6addr_chain,nb);
 }
 
 /*

net/netfilter/nf_conntrack_core.c

@@ -90,8 +90,8 @@ static int nf_conntrack_vmalloc;
 static unsigned int nf_conntrack_next_id;
 static unsigned int nf_conntrack_expect_next_id;
 #ifdef CONFIG_NF_CONNTRACK_EVENTS
-struct notifier_block *nf_conntrack_chain;
-struct notifier_block *nf_conntrack_expect_chain;
+ATOMIC_NOTIFIER_HEAD(nf_conntrack_chain);
+ATOMIC_NOTIFIER_HEAD(nf_conntrack_expect_chain);
 
 DEFINE_PER_CPU(struct nf_conntrack_ecache, nf_conntrack_ecache);
 
@@ -103,7 +103,7 @@ __nf_ct_deliver_cached_events(struct nf_conntrack_ecache *ecache)
 	DEBUGP("ecache: delivering events for %p\n", ecache->ct);
 	if (nf_ct_is_confirmed(ecache->ct) && !nf_ct_is_dying(ecache->ct)
 	    && ecache->events)
-		notifier_call_chain(&nf_conntrack_chain, ecache->events,
+		atomic_notifier_call_chain(&nf_conntrack_chain, ecache->events,
 				    ecache->ct);
 
 	ecache->events = 0;

net/netlink/af_netlink.c

@@ -123,7 +123,7 @@ static void netlink_destroy_callback(struct netlink_callback *cb);
 static DEFINE_RWLOCK(nl_table_lock);
 static atomic_t nl_table_users = ATOMIC_INIT(0);
 
-static struct notifier_block *netlink_chain;
+static ATOMIC_NOTIFIER_HEAD(netlink_chain);
 
 static u32 netlink_group_mask(u32 group)
 {
@@ -469,7 +469,8 @@ static int netlink_release(struct socket *sock)
 						.protocol = sk->sk_protocol,
 						.pid = nlk->pid,
 					  };
-		notifier_call_chain(&netlink_chain, NETLINK_URELEASE, &n);
+		atomic_notifier_call_chain(&netlink_chain,
+				NETLINK_URELEASE, &n);
 	}	
 
 	if (nlk->module)
@@ -1695,12 +1696,12 @@ static struct file_operations netlink_seq_fops = {
 
 int netlink_register_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_register(&netlink_chain, nb);
+	return atomic_notifier_chain_register(&netlink_chain, nb);
 }
 
 int netlink_unregister_notifier(struct notifier_block *nb)
 {
-	return notifier_chain_unregister(&netlink_chain, nb);
+	return atomic_notifier_chain_unregister(&netlink_chain, nb);
 }
                 
 static const struct proto_ops netlink_ops = {