[PATCH] Add panic blinking to 2.6

This patch readds the panic blinking that was in 2.4 to 2.6.  This is
useful to see when you're in X that the machine has paniced 

It addresses previously criticism.
It should work now when the keyboard interrupt is off.
It doesn't fully emulate the handler, but has a timeout
for this case.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/input/serio/i8042.c

@@ -813,6 +813,41 @@ void i8042_controller_cleanup(void)
 }
 
 
+static int blink_frequency = 500;
+module_param_named(panicblink, blink_frequency, int, 0600);
+
+/* Catch the case when the kbd interrupt is off */
+#define DELAY do { mdelay(1); if (++delay > 10) return delay; } while(0)
+
+/* Tell the user who may be running in X and not see the console that we have
+   panic'ed. This is to distingush panics from "real" lockups.  */
+static long i8042_panic_blink(long count)
+{
+	long delay = 0;
+	static long last_blink;
+	static char led;
+	/* Roughly 1/2s frequency. KDB uses about 1s. Make sure it is
+	   different. */
+	if (!blink_frequency)
+		return 0;
+	if (count - last_blink < blink_frequency)
+		return 0;
+	led ^= 0x01 | 0x04;
+	while (i8042_read_status() & I8042_STR_IBF)
+		DELAY;
+	i8042_write_data(0xed); /* set leds */
+	DELAY;
+	while (i8042_read_status() & I8042_STR_IBF)
+		DELAY;
+	DELAY;
+	i8042_write_data(led);
+	DELAY;
+	last_blink = count;
+	return delay;
+}
+
+#undef DELAY
+
 /*
  * Here we try to restore the original BIOS settings
  */
@@ -863,6 +898,8 @@ static int i8042_controller_resume(void)
  */
 	mod_timer(&i8042_timer, jiffies + I8042_POLL_PERIOD);
 
+	panic_blink = i8042_panic_blink;
+
 	return 0;
 }
 
@@ -1077,6 +1114,8 @@ void __exit i8042_exit(void)
 	driver_unregister(&i8042_driver);
 
 	i8042_platform_exit();
+
+	panic_blink = NULL;
 }
 
 module_init(i8042_init);

include/linux/kernel.h

@@ -66,6 +66,7 @@ void __might_sleep(char *file, int line);
 	})
 
 extern struct notifier_block *panic_notifier_list;
+extern long (*panic_blink)(long time);
 NORET_TYPE void panic(const char * fmt, ...)
 	__attribute__ ((NORET_AND format (printf, 1, 2)));
 asmlinkage NORET_TYPE void do_exit(long error_code)

kernel/panic.c

@@ -36,6 +36,15 @@ static int __init panic_setup(char *str)
 }
 __setup("panic=", panic_setup);
 
+static long no_blink(long time)
+{
+	return 0;
+}
+
+/* Returns how long it waited in ms */
+long (*panic_blink)(long time) = no_blink;
+EXPORT_SYMBOL(panic_blink);
+
 /**
  *	panic - halt the system
  *	@fmt: The text string to print
@@ -48,6 +57,7 @@ __setup("panic=", panic_setup);
  
 NORET_TYPE void panic(const char * fmt, ...)
 {
+	long i;
 	static char buf[1024];
 	va_list args;
 #if defined(CONFIG_ARCH_S390)
@@ -69,15 +79,16 @@ NORET_TYPE void panic(const char * fmt, ...)
 
 	if (panic_timeout > 0)
 	{
-		int i;
 		/*
 	 	 * Delay timeout seconds before rebooting the machine. 
 		 * We can't use the "normal" timers since we just panicked..
 	 	 */
 		printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout);
-		for (i = 0; i < panic_timeout; i++) {
+		for (i = 0; i < panic_timeout*1000; ) {
 			touch_nmi_watchdog();
-			mdelay(1000);
+			i += panic_blink(i);
+			mdelay(1);
+			i++;
 		}
 		/*
 		 *	Should we run the reboot notifier. For the moment Im
@@ -98,8 +109,11 @@ NORET_TYPE void panic(const char * fmt, ...)
         disabled_wait(caller);
 #endif
 	local_irq_enable();
-	for (;;)
-		;
+	for (i = 0;;) {
+		i += panic_blink(i);
+		mdelay(1);
+		i++;
+	}
 }
 
 EXPORT_SYMBOL(panic);