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>

4 files changed, 19 insertions, 23 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index d97d0a8e87dc..e3d556427b2e 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2094,7 +2094,16 @@ static inline void sched_autogroup_exit(struct signal_struct *sig) { }
 extern bool yield_to(struct task_struct *p, bool preempt);
 extern void set_user_nice(struct task_struct *p, long nice);
 extern int task_prio(const struct task_struct *p);
-extern int task_nice(const struct task_struct *p);
+/**
+ * task_nice - return the nice value of a given task.
+ * @p: the task in question.
+ *
+ * Return: The nice value [ -20 ... 0 ... 19 ].
+ */
+static inline int task_nice(const struct task_struct *p)
+{
+        return PRIO_TO_NICE((p)->static_prio);
+}
 extern int can_nice(const struct task_struct *p, const int nice);
 extern int task_curr(const struct task_struct *p);
 extern int idle_cpu(int cpu);
diff --git a/include/linux/sched/prio.h b/include/linux/sched/prio.h
index 13216f16762e..410ccb74c9e6 100644
--- a/include/linux/sched/prio.h
+++ b/include/linux/sched/prio.h
@@ -27,7 +27,6 @@
  */
 #define NICE_TO_PRIO(nice)      (MAX_RT_PRIO + (nice) + 20)
 #define PRIO_TO_NICE(prio)      ((prio) - MAX_RT_PRIO - 20)
-#define TASK_NICE(p)            PRIO_TO_NICE((p)->static_prio)
 
 /*
  * 'User priority' is the nice value converted to something we
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 210a12acf2cd..104c8164e04f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3000,7 +3000,7 @@ void set_user_nice(struct task_struct *p, long nice)
         unsigned long flags;
         struct rq *rq;
 
-        if (TASK_NICE(p) == nice || nice < -20 || nice > 19)
+        if (task_nice(p) == nice || nice < -20 || nice > 19)
                 return;
         /*
          * We have to be careful, if called from sys_setpriority(),
@@ -3078,7 +3078,7 @@ SYSCALL_DEFINE1(nice, int, increment)
         if (increment > 40)
                 increment = 40;
 
-        nice = TASK_NICE(current) + increment;
+        nice = task_nice(current) + increment;
         if (nice < -20)
                 nice = -20;
         if (nice > 19)
@@ -3111,18 +3111,6 @@ int task_prio(const struct task_struct *p)
 }
 
 /**
- * task_nice - return the nice value of a given task.
- * @p: the task in question.
- *
- * Return: The nice value [ -20 ... 0 ... 19 ].
- */
-int task_nice(const struct task_struct *p)
-{
-        return TASK_NICE(p);
-}
-EXPORT_SYMBOL(task_nice);
-
-/**
  * idle_cpu - is a given cpu idle currently?
  * @cpu: the processor in question.
  *
@@ -3321,7 +3309,7 @@ recheck:
          */
         if (user && !capable(CAP_SYS_NICE)) {
                 if (fair_policy(policy)) {
-                        if (attr->sched_nice < TASK_NICE(p) &&
+                        if (attr->sched_nice < task_nice(p) &&
                             !can_nice(p, attr->sched_nice))
                                 return -EPERM;
                 }
@@ -3345,7 +3333,7 @@ recheck:
                  * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
                  */
                 if (p->policy == SCHED_IDLE && policy != SCHED_IDLE) {
-                        if (!can_nice(p, TASK_NICE(p)))
+                        if (!can_nice(p, task_nice(p)))
                                 return -EPERM;
                 }
 
@@ -3385,7 +3373,7 @@ recheck:
          * If not changing anything there's no need to proceed further:
          */
         if (unlikely(policy == p->policy)) {
-                if (fair_policy(policy) && attr->sched_nice != TASK_NICE(p))
+                if (fair_policy(policy) && attr->sched_nice != task_nice(p))
                         goto change;
                 if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
                         goto change;
@@ -3837,7 +3825,7 @@ SYSCALL_DEFINE3(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
         else if (task_has_rt_policy(p))
                 attr.sched_priority = p->rt_priority;
         else
-                attr.sched_nice = TASK_NICE(p);
+                attr.sched_nice = task_nice(p);
 
         rcu_read_unlock();
 
@@ -7010,7 +6998,7 @@ void normalize_rt_tasks(void)
                          * Renice negative nice level userspace
                          * tasks back to 0:
                          */
-                        if (TASK_NICE(p) < 0 && p->mm)
+                        if (task_nice(p) < 0 && p->mm)
                                 set_user_nice(p, 0);
                         continue;
                 }
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 99947919e30b..58624a65f124 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -142,7 +142,7 @@ void account_user_time(struct task_struct *p, cputime_t cputime,
         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 @@ static void account_guest_time(struct task_struct *p, cputime_t cputime,
         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 {