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: TAMUKI Shoichi <tamuki@linet.gr.jp>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Russell King <linux@arm.linux.org.uk>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Cc: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/panic.c b/kernel/panic.c
index 3b16cd9..3e9037a 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -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 @@
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 @@
{
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 @@
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 @@
*/
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 @@
}
#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);
}
}