[RFC] Add notifier_call_chain before sync in panic

[Norihiko Mukouyama]

Dear All,

I made a patch that add notifier_call_chain() before sys_sync() in  panic().
I also added notifier_call_chain() in die() because of being processed
Oops similar to kernel panic.

In recent kernel structure,  clean up routine be hooked to existing 
notifier_call_chain() after sys_sync() in panic().
But, there are some cases that clean up should be called prior to sys_sync() in
my opinion. 

Clean up routine often has to wait for a long time to finish sys_sync().
Furthermore,if file system is broken (sys_sync() seldom ends), clean-up often
fails to be invoked.


My patch enables the invocation of clean up before falling into long wait 
or stalling.
There are also some other merits by my patch. For example, clustering system
can use this hook to tell failure to other machine.

Could you apply attached patch?

Thanks.

Norihiko Nukouyama

diff -uNr linux-2.6.3.org/arch/i386/kernel/traps.c linux-2.6.3/arch/i386/kernel/traps.c
--- linux-2.6.3.org/arch/i386/kernel/traps.c	2004-02-18 12:57:17.000000000 +0900
+++ linux-2.6.3/arch/i386/kernel/traps.c	2004-02-27 08:42:10.000000000 +0900
@@ -54,6 +54,10 @@
 
 #include "mach_traps.h"
 
+#include<linux/notifier.h>
+struct notifier_block *trap_notifier_list;
+EXPORT_SYMBOL(trap_notifier_list);
+
 asmlinkage int system_call(void);
 asmlinkage void lcall7(void);
 asmlinkage void lcall27(void);
@@ -262,6 +266,7 @@
 	handle_BUG(regs);
 	printk("%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);
 	show_registers(regs);
+	notifier_call_chain(&trap_notifier_list , 0 , NULL);
 	bust_spinlocks(0);
 	spin_unlock_irq(&die_lock);
 	if (in_interrupt())
diff -uNr linux-2.6.3.org/include/linux/kernel.h linux-2.6.3/include/linux/kernel.h
--- linux-2.6.3.org/include/linux/kernel.h	2004-02-18 12:57:11.000000000 +0900
+++ linux-2.6.3/include/linux/kernel.h	2004-02-27 08:44:15.000000000 +0900
@@ -55,6 +55,8 @@
 #endif
 
 extern struct notifier_block *panic_notifier_list;
+extern struct notifier_block *prepanic_notifier_list;
+extern struct notifier_block *trap_notifier_list;
 NORET_TYPE void panic(const char * fmt, ...)
 	__attribute__ ((NORET_AND format (printf, 1, 2)));
 asmlinkage NORET_TYPE void do_exit(long error_code)
diff -uNr linux-2.6.3.org/kernel/panic.c linux-2.6.3/kernel/panic.c
--- linux-2.6.3.org/kernel/panic.c	2004-02-18 12:59:34.000000000 +0900
+++ linux-2.6.3/kernel/panic.c	2004-02-27 08:38:43.000000000 +0900
@@ -28,8 +28,10 @@
 EXPORT_SYMBOL(panic_timeout);
 
 struct notifier_block *panic_notifier_list;
+struct notifier_block *prepanic_notifier_list;
 
 EXPORT_SYMBOL(panic_notifier_list);
+EXPORT_SYMBOL(prepanic_notifier_list);
 
 static int __init panic_setup(char *str)
 {
@@ -61,6 +63,7 @@
 	vsnprintf(buf, sizeof(buf), fmt, args);
 	va_end(args);
 	printk(KERN_EMERG "Kernel panic: %s\n",buf);
+	notifier_call_chain(&prepanic_notifier_list , 0 , NULL);
 	if (in_interrupt())
 		printk(KERN_EMERG "In interrupt handler - not syncing\n");
 	else if (!current->pid)
-
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