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| author | Chris Wilson <chris@chris-wilson.co.uk> | 2010-08-09 14:20:10 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-08-12 09:53:39 -0700 |
| commit | 4936a3b90d79dd8775c6ac23c2cf2dcebe29abde (patch) | |
| tree | ab4fb288fd00bb50b5aebcc93fa476cc2c1d53be | |
| parent | deda2e81961e96be4f2c09328baca4710a2fd1a0 (diff) | |
| download | linux-3.10-4936a3b90d79dd8775c6ac23c2cf2dcebe29abde.tar.gz linux-3.10-4936a3b90d79dd8775c6ac23c2cf2dcebe29abde.tar.bz2 linux-3.10-4936a3b90d79dd8775c6ac23c2cf2dcebe29abde.zip | |
x86/hpet: Use the FSEC_PER_SEC constant for femto-second periods
The current computation, introduced with f12a15be63, of FSEC_PER_SEC using
the multiplication of (FSEC_PER_NSEC * NSEC_PER_SEC) is performed only
with 32bit integers on small machines, resulting in an overflow and a
*very* short intervals being programmed. An interrupt storm follows.
Note that we also have to specify FSEC_PER_SEC as being long long to
overcome the same limitations.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | arch/x86/kernel/hpet.c | 4 | ||||
| -rw-r--r-- | include/linux/time.h | 2 |
2 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c index 33dbcc4ec5f..351f9c0fea1 100644 --- a/arch/x86/kernel/hpet.c +++ b/arch/x86/kernel/hpet.c @@ -582,7 +582,7 @@ static void init_one_hpet_msi_clockevent(struct hpet_dev *hdev, int cpu) * scaled math multiplication factor for nanosecond to hpet tick * conversion. */ - hpet_freq = 1000000000000000ULL; + hpet_freq = FSEC_PER_SEC; do_div(hpet_freq, hpet_period); evt->mult = div_sc((unsigned long) hpet_freq, NSEC_PER_SEC, evt->shift); @@ -837,7 +837,7 @@ static int hpet_clocksource_register(void) * cyc/sec = FSEC_PER_SEC/hpet_period(fsec/cyc) * cyc/sec = (FSEC_PER_NSEC * NSEC_PER_SEC)/hpet_period */ - hpet_freq = FSEC_PER_NSEC * NSEC_PER_SEC; + hpet_freq = FSEC_PER_SEC; do_div(hpet_freq, hpet_period); clocksource_register_hz(&clocksource_hpet, (u32)hpet_freq); diff --git a/include/linux/time.h b/include/linux/time.h index cb34e35faba..12612701b1a 100644 --- a/include/linux/time.h +++ b/include/linux/time.h @@ -38,7 +38,7 @@ extern struct timezone sys_tz; #define NSEC_PER_MSEC 1000000L #define USEC_PER_SEC 1000000L #define NSEC_PER_SEC 1000000000L -#define FSEC_PER_SEC 1000000000000000L +#define FSEC_PER_SEC 1000000000000000LL #define TIME_T_MAX (time_t)((1UL << ((sizeof(time_t) << 3) - 1)) - 1) |