Readd panic blinking in 2.6
PATCH 1/1 Readd panic blinking in 2.6
Later 2.4 had a feature that would make the keyboard LEDs blink when a panic occurred. This patch adds it to 2.6 too.
This is useful when your machine is in X and locks up. With the blinking keyboard lights you at least know that a panic happened, not that it randomly locked up.
I cleaned it up a bit and ported it to the new keyboard driver. Unlike 2.4 it also works now with panic=... and doesn't rely on the timer interrupt ticking anymore. It's also clear, now it uses a generic callback, no ifdefs. Should also work now with modular keyboard driver and the panic blink frequency can be configured in sysfs (this is useful for a few KVMs who don't like this). Setting it to 0 turns it off.
Work left to do: find some way to use HLT in the busy loops. Currently machines eat a lot of power in panic and sometimes they hang in this state for days until somebody can reset them. Unfortunately this will require relying on the timer interrupts again.
P.S. Before anyone asks: no, i'm not interested in morse code output.
drivers/input/serio/i8042.c renamed from drivers/input/serio/i8042.c-PANIC +38 -0
@@ -887,6 +887,40 @@ 0 }; +static int blink_frequency =500 ; +module_param_named (panicblink, blink_frequency, int,0600 ); + +#define DELAY mdelay(1), delay++ + +/* 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 +/* * Suspend/resume handlers for the new PM scheme (driver model) */
@@ -1047,6 +1081,8 @@register_reboot_notifier (&i8042_notifier); + panic_blink = i8042_panic_blink; +return 0 ; }
@@ -1077,6 +1113,8 @@driver_unregister (&i8042_driver);i8042_platform_exit (); + + panic_blink =NULL ; }module_init (i8042_init);
include/linux/kernel.h renamed from include/linux/kernel.h-PANIC +1 -0
@@ -66,6 +66,7 @@ })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 renamed from kernel/panic.c-PANIC +19 -5
@@ -37,6 +37,15 @@ }__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
@@ -49,6 +58,7 @@ NORET_TYPE void panic(const char * fmt, ...) { +long i;static char buf[1024 ];va_list args;#if defined(CONFIG_ARCH_S390 )
@@ -70,15 +80,16 @@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
@@ -99,8 +110,11 @@disabled_wait (caller);#endif local_irq_enable (); -for (;;) - ; +for (i =0 ;;) { + i +=panic_blink (i); +mdelay (1 ); + i++; + } }EXPORT_SYMBOL (panic);
Quoted 18 lines · Andi Kleen
diff -u linux-2.6.9rc2-bk11/drivers/input/serio/i8042.c-PANIC
linux-2.6.9rc2-bk11/drivers/input/serio/i8042.cdrivers/input/serio/i8042.c renamed from drivers/input/serio/i8042.c-PANIC +11
-0@@ -887,6 +887,40 @@ 0 }; +static int blink_frequency =500 ; +module_param_named (panicblink, blink_frequency, int,0600 ); + +#define DELAY mdelay(1), delay++ + +/* 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;
drivers/input/serio/i8042.c line 910
Quoted 10 lines
drivers/input/serio/i8042.c renamed from drivers/input/serio/i8042.c-PANIC +10
-0+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 ;
This here relies on interrupts working, since to clear IBF you need to read from the input port, which is only done in the interrupt routine. What you should do here is to disable the interrupts on the i8042 by setting the CTR to an appropriate value and then flush the input port after a response from the keyboard has arrived.
drivers/input/serio/i8042.c line 920
Quoted 10 lines
drivers/input/serio/i8042.c renamed from drivers/input/serio/i8042.c-PANIC +10
-0+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; +}
Also, you shouldn't need the DELAY macro, as i8042.c already has the primitives to do all the waiting.
Something like
spin_lock_irqsave(&i8042_lock, flags); i8042_flush(); i8042_ctr &= ~I8042_CTR_KBDINT & ~I8042_CTR_AUXINT; i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR); i8042_wait_write(); i8042_write_data(0xed); i8042_wait_read(); i8042_flush(); i8042_wait_write(); i8042_write_data(led); i8042_wait_read(); i8042_flush(); spin_unlock_irqrestore(&i8042_lock, flags);
would be safer and more correct.
Signature · 2 lines
Vojtech Pavlik SuSE Labs, SuSE CR
Salut,
Quoted 2 lines · Andi Kleen
Later 2.4 had a feature that would make the keyboard LEDs blink when a panic occurred. This patch adds it to 2.6 too.
What happened to the morse code panic patches? ;)
Tonnerre
Quoted 7 lines · Tonnerre
Salut,
Quoted 2 lines · Andi Kleen
Later 2.4 had a feature that would make the keyboard LEDs blink when a panic occurred. This patch adds it to 2.6 too.
What happened to the morse code panic patches? ;)
You didn't read my full original mail, did you?
-Andi
Quoted 17 lines
Something like
spin_lock_irqsave(&i8042_lock, flags); i8042_flush(); i8042_ctr &= ~I8042_CTR_KBDINT & ~I8042_CTR_AUXINT; i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR); i8042_wait_write(); i8042_write_data(0xed); i8042_wait_read(); i8042_flush(); i8042_wait_write(); i8042_write_data(led); i8042_wait_read(); i8042_flush(); spin_unlock_irqrestore(&i8042_lock, flags);
Quoted 1 line
would be safer and more correct.
That all takes far too many locks. The risk of deadlocking during panic is too great. I think the delay is fine (worked great under 2.4), just need to fix the IBF issue you mentioned.
-Andi
Quoted 17 lines · Andi Kleen
Quoted 17 lines
Something like
spin_lock_irqsave(&i8042_lock, flags); i8042_flush(); i8042_ctr &= ~I8042_CTR_KBDINT & ~I8042_CTR_AUXINT; i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR); i8042_wait_write(); i8042_write_data(0xed); i8042_wait_read(); i8042_flush(); i8042_wait_write(); i8042_write_data(led); i8042_wait_read(); i8042_flush(); spin_unlock_irqrestore(&i8042_lock, flags);
Quoted 3 lines
Quoted 1 line
would be safer and more correct.
That all takes far too many locks.
Ouch, yes. Just ignore the locks then. As it is, it would deadlock immediately.
Quoted 3 lines
The risk of deadlocking during
panic is too great. I think the delay is fine (worked great under 2.4), just need to fix the IBF issue you mentioned.
Signature · 2 lines
Vojtech Pavlik SuSE Labs, SuSE CR