ktime: Kill non-scalar ktime_t implementation for 2038

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>

3 files changed, 2 insertions, 63 deletions

diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index f448513a45ed..feccfd888732 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -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
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 2f4ef8a1e5ff..19f211051c35 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -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
  */
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index b94fa3652aaa..cafef242d8f9 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -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);