Commit 4936a3b9 authored by Chris Wilson's avatar Chris Wilson Committed by Linus Torvalds

x86/hpet: Use the FSEC_PER_SEC constant for femto-second periods

The current computation, introduced with f12a15be, 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: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarJohn Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Acked-by: default avatarH. Peter Anvin <hpa@zytor.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent deda2e81
......@@ -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);
......
......@@ -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)
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment