[PATCH] contify some scheduler functions

Several scheduler macros only read from the task struct, mark them const.
It may help the compiler generate better code.
Signed-off-by: Keith Owens <kaos@ocs.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/sched.h

@@ -688,9 +688,9 @@ extern void sched_balance_exec(void);
 
 extern void sched_idle_next(void);
 extern void set_user_nice(task_t *p, long nice);
-extern int task_prio(task_t *p);
-extern int task_nice(task_t *p);
-extern int task_curr(task_t *p);
+extern int task_prio(const task_t *p);
+extern int task_nice(const task_t *p);
+extern int task_curr(const task_t *p);
 extern int idle_cpu(int cpu);
 
 void yield(void);
@@ -917,7 +917,7 @@ extern void wait_task_inactive(task_t * p);
 #define while_each_thread(g, t) \
 	while ((t = next_thread(t)) != g)
 
-extern task_t * FASTCALL(next_thread(task_t *p));
+extern task_t * FASTCALL(next_thread(const task_t *p));
 
 #define thread_group_leader(p)	(p->pid == p->tgid)
 
@@ -1058,7 +1058,7 @@ extern void signal_wake_up(struct task_struct *t, int resume_stopped);
  */
 #ifdef CONFIG_SMP
 
-static inline unsigned int task_cpu(struct task_struct *p)
+static inline unsigned int task_cpu(const struct task_struct *p)
 {
 	return p->thread_info->cpu;
 }
@@ -1070,7 +1070,7 @@ static inline void set_task_cpu(struct task_struct *p, unsigned int cpu)
 
 #else
 
-static inline unsigned int task_cpu(struct task_struct *p)
+static inline unsigned int task_cpu(const struct task_struct *p)
 {
 	return 0;
 }

kernel/exit.c

@@ -834,10 +834,10 @@ asmlinkage long sys_exit(int error_code)
 	do_exit((error_code&0xff)<<8);
 }
 
-task_t fastcall *next_thread(task_t *p)
+task_t fastcall *next_thread(const task_t *p)
 {
-	struct pid_link *link = p->pids + PIDTYPE_TGID;
-	struct list_head *tmp, *head = &link->pidptr->task_list;
+	const struct pid_link *link = p->pids + PIDTYPE_TGID;
+	const struct list_head *tmp, *head = &link->pidptr->task_list;
 
 #ifdef CONFIG_SMP
 	if (!p->sighand)

kernel/sched.c

@@ -546,7 +546,7 @@ static inline void resched_task(task_t *p)
  * task_curr - is this task currently executing on a CPU?
  * @p: the task in question.
  */
-inline int task_curr(task_t *p)
+inline int task_curr(const task_t *p)
 {
 	return cpu_curr(task_cpu(p)) == p;
 }
@@ -2658,7 +2658,7 @@ asmlinkage long sys_nice(int increment)
  * RT tasks are offset by -200. Normal tasks are centered
  * around 0, value goes from -16 to +15.
  */
-int task_prio(task_t *p)
+int task_prio(const task_t *p)
 {
 	return p->prio - MAX_RT_PRIO;
 }
@@ -2667,7 +2667,7 @@ int task_prio(task_t *p)
  * task_nice - return the nice value of a given task.
  * @p: the task in question.
  */
-int task_nice(task_t *p)
+int task_nice(const task_t *p)
 {
 	return TASK_NICE(p);
 }