sched: Implement task_nice() as static inline function

As patch "sched: Move the priority specific bits into a new header file" exposes
the priority related macros in linux/sched/prio.h, we don't have to implement
task_nice() in kernel/sched/core.c any more.

This patch implements it in linux/sched/sched.h as static inline function,
saving the kernel stack and enhancing performance a bit.

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Cc: clark.williams@gmail.com
Cc: rostedt@goodmis.org
Cc: raistlin@linux.it
Cc: juri.lelli@gmail.com
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1390878045-7096-1-git-send-email-yangds.fnst@cn.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 9994791..58624a6 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -142,7 +142,7 @@
 	p->utimescaled += cputime_scaled;
 	account_group_user_time(p, cputime);
 
-	index = (TASK_NICE(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
+	index = (task_nice(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
 
 	/* Add user time to cpustat. */
 	task_group_account_field(p, index, (__force u64) cputime);
@@ -169,7 +169,7 @@
 	p->gtime += cputime;
 
 	/* Add guest time to cpustat. */
-	if (TASK_NICE(p) > 0) {
+	if (task_nice(p) > 0) {
 		cpustat[CPUTIME_NICE] += (__force u64) cputime;
 		cpustat[CPUTIME_GUEST_NICE] += (__force u64) cputime;
 	} else {