Provide a failsafe mechanism to avoid kernel spinning for ever at read_hpet_tsc during early kernel bootup.
This failsafe mechanism was introduced in 21-rc, http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=2f7a2a79c3ebb44f8b1b7d9b4fd3a650eb69e544 But looks like the hpet split from time.c lost the commit. This patch reintroduces the failsafe mechanism Signed-off-by: Ravikiran Thirumalai <[EMAIL PROTECTED]> Signed-off-by: Shai Fultheim <[EMAIL PROTECTED]> Cc: Jack Steiner <[EMAIL PROTECTED]> Cc: john stultz <[EMAIL PROTECTED]> Cc: Andi Kleen <[EMAIL PROTECTED]> Index: linux-2.6.21-rc5/arch/x86_64/kernel/hpet.c =================================================================== --- linux-2.6.21-rc5.orig/arch/x86_64/kernel/hpet.c 2007-04-11 16:03:05.000000000 -0700 +++ linux-2.6.21-rc5/arch/x86_64/kernel/hpet.c 2007-04-11 18:49:36.000000000 -0700 @@ -191,6 +191,7 @@ int hpet_reenable(void) #define TICK_COUNT 100000000 #define TICK_MIN 5000 +#define MAX_TRIES 5 /* * Some platforms take periodic SMI interrupts with 5ms duration. Make sure none @@ -198,13 +199,15 @@ int hpet_reenable(void) */ static void __init read_hpet_tsc(int *hpet, int *tsc) { - int tsc1, tsc2, hpet1; + int tsc1, tsc2, hpet1, i; - do { + for (i = 0; i < MAX_TRIES; i++) { tsc1 = get_cycles_sync(); hpet1 = hpet_readl(HPET_COUNTER); tsc2 = get_cycles_sync(); - } while (tsc2 - tsc1 > TICK_MIN); + if (tsc2 - tsc1 > TICK_MIN) + break; + } *hpet = hpet1; *tsc = tsc2; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
