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Commit c7ff0d9c authored by TAMUKI Shoichi's avatar TAMUKI Shoichi Committed by Linus Torvalds
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panic: keep blinking in spite of long spin timer mode 



To keep panic_timeout accuracy when running under a hypervisor, the
current implementation only spins on long time (1 second) calls to mdelay.
 That brings a good effect, but the problem is the keyboard LEDs don't
blink at all on that situation.

This patch changes to call to panic_blink_enter() between every mdelay and
keeps blinking in spite of long spin timer mode.

The time to call to mdelay is now 100ms.  Even this change will keep
panic_timeout accuracy enough when running under a hypervisor.

Signed-off-by: default avatarTAMUKI Shoichi <tamuki@linet.gr.jp>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Russell King <linux@arm.linux.org.uk>
Acked-by: default avatarDmitry Torokhov <dtor@mail.ru>
Cc: Anton Blanchard <anton@samba.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent bebf8cfa

Documentation/kernel-parameters.txt

+0 −3
Original line number Diff line number Diff line
@@ -915,9 +915,6 @@ and is between 256 and 4096 characters. It is defined in the file 
			     controller

	i8042.nopnp	[HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX

			     controllers

	i8042.panicblink=

			[HW] Frequency with which keyboard LEDs should blink

			     when kernel panics (default is 0.5 sec)

	i8042.reset	[HW] Reset the controller during init and cleanup

	i8042.unlock	[HW] Unlock (ignore) the keylock

arch/arm/mach-s3c2440/mach-gta02.c

+5 −12
Original line number Diff line number Diff line
@@ -90,24 +90,17 @@ 
static struct pcf50633 *gta02_pcf;



/*

 * This gets called every 1ms when we paniced.

 * This gets called frequently when we paniced.

 */



static long gta02_panic_blink(long count)

static long gta02_panic_blink(int state)

{

	long delay = 0;

	static long last_blink;

	static char led;

	char led;



	/* Fast blink: 200ms period. */

	if (count - last_blink < 100)

		return 0;



	led ^= 1;

	led = (state) ? 1 : 0;

	gpio_direction_output(GTA02_GPIO_AUX_LED, led);



	last_blink = count;



	return delay;

}
@@ -556,7 +549,7 @@ static void gta02_poweroff(void) 


static void __init gta02_machine_init(void)

{

	/* Set the panic callback to make AUX LED blink at ~5Hz. */

	/* Set the panic callback to turn AUX LED on or off. */

	panic_blink = gta02_panic_blink;



	s3c_pm_init();

drivers/input/serio/i8042.c

+5 −20
Original line number Diff line number Diff line
@@ -61,10 +61,6 @@ static bool i8042_noloop; 
module_param_named(noloop, i8042_noloop, bool, 0);

MODULE_PARM_DESC(noloop, "Disable the AUX Loopback command while probing for the AUX port");



static unsigned int i8042_blink_frequency = 500;

module_param_named(panicblink, i8042_blink_frequency, uint, 0600);

MODULE_PARM_DESC(panicblink, "Frequency with which keyboard LEDs should blink when kernel panics");



#ifdef CONFIG_X86

static bool i8042_dritek;

module_param_named(dritek, i8042_dritek, bool, 0);
@@ -1030,8 +1026,8 @@ static void i8042_controller_reset(void) 




/*

 * i8042_panic_blink() will flash the keyboard LEDs and is called when

 * kernel panics. Flashing LEDs is useful for users running X who may

 * i8042_panic_blink() will turn the keyboard LEDs on or off and is called

 * when kernel panics. Flashing LEDs is useful for users running X who may

 * not see the console and will help distingushing panics from "real"

 * lockups.

 *
@@ -1041,22 +1037,12 @@ static void i8042_controller_reset(void) 


#define DELAY do { mdelay(1); if (++delay > 10) return delay; } while(0)



static long i8042_panic_blink(long count)

static long i8042_panic_blink(int state)

{

	long delay = 0;

	static long last_blink;

	static char led;



	/*

	 * We expect frequency to be about 1/2s. KDB uses about 1s.

	 * Make sure they are different.

	 */

	if (!i8042_blink_frequency)

		return 0;

	if (count - last_blink < i8042_blink_frequency)

		return 0;

	char led;



	led ^= 0x01 | 0x04;

	led = (state) ? 0x01 | 0x04 : 0;

	while (i8042_read_status() & I8042_STR_IBF)

		DELAY;

	dbg("%02x -> i8042 (panic blink)", 0xed);
@@ -1069,7 +1055,6 @@ static long i8042_panic_blink(long count) 
	dbg("%02x -> i8042 (panic blink)", led);

	i8042_write_data(led);

	DELAY;

	last_blink = count;

	return delay;

}

include/linux/kernel.h

+1 −1
Original line number Diff line number Diff line
@@ -177,7 +177,7 @@ struct va_format { 
};



extern struct atomic_notifier_head panic_notifier_list;

extern long (*panic_blink)(long time);

extern long (*panic_blink)(int state);

NORET_TYPE void panic(const char * fmt, ...)

	__attribute__ ((NORET_AND format (printf, 1, 2))) __cold;

extern void oops_enter(void);

kernel/panic.c

+26 −32
Original line number Diff line number Diff line
@@ -24,6 +24,9 @@ 
#include <linux/nmi.h>

#include <linux/dmi.h>



#define PANIC_TIMER_STEP 100

#define PANIC_BLINK_SPD 18



int panic_on_oops;

static unsigned long tainted_mask;

static int pause_on_oops;
@@ -36,36 +39,15 @@ ATOMIC_NOTIFIER_HEAD(panic_notifier_list); 


EXPORT_SYMBOL(panic_notifier_list);



/* Returns how long it waited in ms */

long (*panic_blink)(long time);

EXPORT_SYMBOL(panic_blink);



static void panic_blink_one_second(void)

static long no_blink(int state)

{

	static long i = 0, end;



	if (panic_blink) {

		end = i + MSEC_PER_SEC;



		while (i < end) {

			i += panic_blink(i);

			mdelay(1);

			i++;

		}

	} else {

		/*

		 * When running under a hypervisor a small mdelay may get

		 * rounded up to the hypervisor timeslice. For example, with

		 * a 1ms in 10ms hypervisor timeslice we might inflate a

		 * mdelay(1) loop by 10x.

		 *

		 * If we have nothing to blink, spin on 1 second calls to

		 * mdelay to avoid this.

		 */

		mdelay(MSEC_PER_SEC);

	}

	return 0;

}



/* Returns how long it waited in ms */

long (*panic_blink)(int state);

EXPORT_SYMBOL(panic_blink);



/**

 *	panic - halt the system

 *	@fmt: The text string to print
@@ -78,7 +60,8 @@ NORET_TYPE void panic(const char * fmt, ...) 
{

	static char buf[1024];

	va_list args;

	long i;

	long i, i_next = 0;

	int state = 0;



	/*

	 * It's possible to come here directly from a panic-assertion and
@@ -117,6 +100,9 @@ NORET_TYPE void panic(const char * fmt, ...) 


	bust_spinlocks(0);



	if (!panic_blink)

		panic_blink = no_blink;



	if (panic_timeout > 0) {

		/*

		 * Delay timeout seconds before rebooting the machine.
@@ -124,9 +110,13 @@ NORET_TYPE void panic(const char * fmt, ...) 
		 */

		printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);



		for (i = 0; i < panic_timeout; i++) {

		for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {

			touch_nmi_watchdog();

			panic_blink_one_second();

			if (i >= i_next) {

				i += panic_blink(state ^= 1);

				i_next = i + 3600 / PANIC_BLINK_SPD;

			}

			mdelay(PANIC_TIMER_STEP);

		}

		/*

		 * This will not be a clean reboot, with everything
@@ -152,9 +142,13 @@ NORET_TYPE void panic(const char * fmt, ...) 
	}

#endif

	local_irq_enable();

	while (1) {

	for (i = 0; ; i += PANIC_TIMER_STEP) {

		touch_softlockup_watchdog();

		panic_blink_one_second();

		if (i >= i_next) {

			i += panic_blink(state ^= 1);

			i_next = i + 3600 / PANIC_BLINK_SPD;

		}

		mdelay(PANIC_TIMER_STEP);

	}

}