sched/cputime: Convert task/group cputime to nsecs

Now that most cputime readers use the transition API which return the
task cputime in old style cputime_t, we can safely store the cputime in
nsecs. This will eventually make cputime statistics less opaque and more
granular. Back and forth convertions between cputime_t and nsecs in order
to deal with cputime_t random granularity won't be needed anymore.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-8-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/kernel/signal.c b/kernel/signal.c
index 218048a..b635221 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1620,8 +1620,8 @@
 	rcu_read_unlock();
 
 	task_cputime_t(tsk, &utime, &stime);
-	info.si_utime = cputime_to_clock_t(utime + tsk->signal->utime);
-	info.si_stime = cputime_to_clock_t(stime + tsk->signal->stime);
+	info.si_utime = cputime_to_clock_t(utime + nsecs_to_cputime(tsk->signal->utime));
+	info.si_stime = cputime_to_clock_t(stime + nsecs_to_cputime(tsk->signal->stime));
 
 	info.si_status = tsk->exit_code & 0x7f;
 	if (tsk->exit_code & 0x80)