posix_cpu_timer: consolidate expiry time type

The posix cpu timer expiry time is stored in a union of two types: a 64
bits field if we rely on scheduler precise accounting, or a cputime_t if
we rely on jiffies.

This results in quite some duplicate code and special cases to handle the
two types.

Just unify this into a single 64 bits field.  cputime_t can always fit
into it.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Olivier Langlois <olivier@trillion01.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/posix-timers.h

@@ -7,14 +7,20 @@
 #include <linux/timex.h>
 #include <linux/alarmtimer.h>
 
-union cpu_time_count {
-	cputime_t cpu;
-	unsigned long long sched;
-};
+
+static inline unsigned long long cputime_to_expires(cputime_t expires)
+{
+	return (__force unsigned long long)expires;
+}
+
+static inline cputime_t expires_to_cputime(unsigned long long expires)
+{
+	return (__force cputime_t)expires;
+}
 
 struct cpu_timer_list {
 	struct list_head entry;
-	union cpu_time_count expires, incr;
+	unsigned long long expires, incr;
 	struct task_struct *task;
 	int firing;
 };