x86: fix hpet timer reinit for x86_64

There's a small problem with hpet_rtc_reinit function - it checks
for the:

	hpet_readl(HPET_COUNTER) - hpet_t1_cmp > 0

to continue increasing both the HPET_T1_CMP (register) and the
hpet_t1_cmp (variable).

But since the HPET_COUNTER is always 32-bit, if the hpet_t1_cmp
is 64-bit this condition will always be FALSE once the latter hits
the 32-bit boundary, and we can have a situation, when we don't
increase the HPET_T1_CMP register high enough.

The result - timer stops ticking, since HPET_T1_CMP becomes less,
than the COUNTER and never increased again.

The solution is (based on Linus's suggestion) to not compare 64-bits
(on 64-bit x86), but to do the comparison on 32-bit signed
integers.

Reported-by: Kirill Korotaev <dev@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 1 deletions

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index 64d5ad0b8add..c761f914430a 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -1075,7 +1075,7 @@ static void hpet_rtc_timer_reinit(void)
                 hpet_t1_cmp += delta;
                 hpet_writel(hpet_t1_cmp, HPET_T1_CMP);
                 lost_ints++;
-        } while ((long)(hpet_readl(HPET_COUNTER) - hpet_t1_cmp) > 0);
+        } while ((s32)(hpet_readl(HPET_COUNTER) - hpet_t1_cmp) > 0);
 
         if (lost_ints) {
                 if (hpet_rtc_flags & RTC_PIE)