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time: prevent the loop in timespec_add_ns() from being optimised away

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Since some architectures don't support __udivdi3().

Signed-off-by: Segher Boessenkool <segher@kernel.crashing.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Segher Boessenkool 2008-03-04 14:59:54 -08:00 committed by Thomas Gleixner
parent e48af19f56
commit 38332cb987
1 changed files with 4 additions and 0 deletions
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4
include/linux/time.h
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@ -174,6 +174,10 @@ static inline void timespec_add_ns(struct timespec *a, u64 ns)
{ {
ns += a->tv_nsec; ns += a->tv_nsec;
while(unlikely(ns >= NSEC_PER_SEC)) { while(unlikely(ns >= NSEC_PER_SEC)) {
/* The following asm() prevents the compiler from
* optimising this loop into a modulo operation. */
asm("" : "+r"(ns));
ns -= NSEC_PER_SEC; ns -= NSEC_PER_SEC;
a->tv_sec++; a->tv_sec++;
} }