timekeeping: Remove timespec64 hack

At this point, we have converted most of the kernel to use timespec64
consistently in place of timespec, so it seems it's time to make
timespec64 the native structure and define timespec in terms of that
one on 64-bit architectures.

Starting with gcc-5, the compiler can completely optimize away the
timespec_to_timespec64 and timespec64_to_timespec functions on 64-bit
architectures. With older compilers, we introduce a couple of extra
copies of local variables, but those are easily avoided by using
the timespec64 based interfaces consistently, as we do in most of the
important code paths already.

The main upside of removing the hack is that printing the tv_sec
field of a timespec64 structure can now use the %lld format
string on all architectures without a cast to time64_t. Without
this patch, the field is a 'long' type and would have to be printed
using %ld on 64-bit architectures.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: y2038@lists.linaro.org
Cc: John Stultz <john.stultz@linaro.org>
Link: https://lkml.kernel.org/r/20180427134016.2525989-2-arnd@arndb.de

1 files changed, 3 insertions, 15 deletions

diff --git a/include/linux/time32.h b/include/linux/time32.h
index d2bcd4377b56..0b14f936100a 100644
--- a/include/linux/time32.h
+++ b/include/linux/time32.h
@@ -18,25 +18,14 @@
 /* timespec64 is defined as timespec here */
 static inline struct timespec timespec64_to_timespec(const struct timespec64 ts64)
 {
-	return ts64;
+	return *(const struct timespec *)&ts64;
 }
 
 static inline struct timespec64 timespec_to_timespec64(const struct timespec ts)
 {
-	return ts;
+	return *(const struct timespec64 *)&ts;
 }
 
-# define timespec_equal			timespec64_equal
-# define timespec_compare		timespec64_compare
-# define set_normalized_timespec	set_normalized_timespec64
-# define timespec_add			timespec64_add
-# define timespec_sub			timespec64_sub
-# define timespec_valid			timespec64_valid
-# define timespec_valid_strict		timespec64_valid_strict
-# define timespec_to_ns			timespec64_to_ns
-# define ns_to_timespec			ns_to_timespec64
-# define timespec_add_ns		timespec64_add_ns
-
 #else
 static inline struct timespec timespec64_to_timespec(const struct timespec64 ts64)
 {
@@ -55,6 +44,7 @@ static inline struct timespec64 timespec_to_timespec64(const struct timespec ts)
 	ret.tv_nsec = ts.tv_nsec;
 	return ret;
 }
+#endif
 
 static inline int timespec_equal(const struct timespec *a,
 				 const struct timespec *b)
@@ -159,8 +149,6 @@ static __always_inline void timespec_add_ns(struct timespec *a, u64 ns)
 	a->tv_nsec = ns;
 }
 
-#endif
-
 /**
  * time_to_tm - converts the calendar time to local broken-down time
  *