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ktime: Kill non-scalar ktime_t implementation for 2038

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The non-scalar ktime_t implementation is basically a timespec
which has to be changed to support dates past 2038 on 32bit
systems.

This patch removes the non-scalar ktime_t implementation, forcing
the scalar s64 nanosecond version on all architectures.

This may have additional performance overhead on some 32bit
systems when converting between ktime_t and timespec structures,
however the majority of 32bit systems (arm and i386) were already
using scalar ktime_t, so no performance regressions will be seen
on those platforms.

On affected platforms, I'm open to finding optimizations, including
avoiding converting to timespecs where possible.

[ tglx: We can now cleanup the ktime_t.tv64 mess, but thats a
  different issue and we can throw a coccinelle script at it ]

Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
This commit is contained in:
John Stultz
2014-07-16 21:03:53 +00:00
parent 76f4108892
commit 24e4a8c3e8
9 changed files with 7 additions and 246 deletions
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4
kernel/time/Kconfig
View File

@@ -20,10 +20,6 @@ config GENERIC_TIME_VSYSCALL
config GENERIC_TIME_VSYSCALL_OLD
bool
# ktime_t scalar 64bit nsec representation
config KTIME_SCALAR
bool
# Old style timekeeping
config ARCH_USES_GETTIMEOFFSET
bool

54
kernel/time/hrtimer.c
View File

@@ -261,60 +261,6 @@ lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
* too large for inlining:
*/
#if BITS_PER_LONG < 64
# ifndef CONFIG_KTIME_SCALAR
/**
* ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
* @kt: addend
* @nsec: the scalar nsec value to add
*
* Returns the sum of kt and nsec in ktime_t format
*/
ktime_t ktime_add_ns(const ktime_t kt, u64 nsec)
{
ktime_t tmp;
if (likely(nsec < NSEC_PER_SEC)) {
tmp.tv64 = nsec;
} else {
unsigned long rem = do_div(nsec, NSEC_PER_SEC);
/* Make sure nsec fits into long */
if (unlikely(nsec > KTIME_SEC_MAX))
return (ktime_t){ .tv64 = KTIME_MAX };
tmp = ktime_set((long)nsec, rem);
}
return ktime_add(kt, tmp);
}
EXPORT_SYMBOL_GPL(ktime_add_ns);
/**
* ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable
* @kt: minuend
* @nsec: the scalar nsec value to subtract
*
* Returns the subtraction of @nsec from @kt in ktime_t format
*/
ktime_t ktime_sub_ns(const ktime_t kt, u64 nsec)
{
ktime_t tmp;
if (likely(nsec < NSEC_PER_SEC)) {
tmp.tv64 = nsec;
} else {
unsigned long rem = do_div(nsec, NSEC_PER_SEC);
tmp = ktime_set((long)nsec, rem);
}
return ktime_sub(kt, tmp);
}
EXPORT_SYMBOL_GPL(ktime_sub_ns);
# endif /* !CONFIG_KTIME_SCALAR */
/*
* Divide a ktime value by a nanosecond value
*/

7
kernel/time/timekeeping.c
View File

@@ -344,11 +344,8 @@ ktime_t ktime_get(void)
nsecs = timekeeping_get_ns(tk) + tk->wall_to_monotonic.tv_nsec;
} while (read_seqcount_retry(&timekeeper_seq, seq));
/*
* Use ktime_set/ktime_add_ns to create a proper ktime on
* 32-bit architectures without CONFIG_KTIME_SCALAR.
*/
return ktime_add_ns(ktime_set(secs, 0), nsecs);
return ktime_set(secs, nsecs);
}
EXPORT_SYMBOL_GPL(ktime_get);