Cleanup: use list macros for task list

arch/i386/kernel/smpboot.c

@@ -828,7 +828,7 @@ static void __init do_boot_cpu (int apicid)
 	 * We remove it from the pidhash and the runqueue
 	 * once we got the process:
 	 */
-	idle = init_task.prev_task;
+	idle = prev_task(&init_task);
 	if (!idle)
 		panic("No idle process for CPU %d", cpu);
 

include/linux/init_task.h

@@ -53,8 +53,7 @@
     active_mm:		&init_mm,					\
     run_list:		LIST_HEAD_INIT(tsk.run_list),			\
     time_slice:		HZ,						\
-    next_task:		&tsk,						\
-    prev_task:		&tsk,						\
+    tasks:		LIST_HEAD_INIT(tsk.tasks),			\
     real_parent:	&tsk,						\
     parent:		&tsk,						\
     children:		LIST_HEAD_INIT(tsk.children),			\

include/linux/sched.h

@@ -250,7 +250,7 @@ struct task_struct {
 	unsigned long cpus_allowed;
 	unsigned int time_slice;
 
-	struct task_struct *next_task, *prev_task;
+	struct list_head tasks;
 
 	struct mm_struct *mm, *active_mm;
 	struct list_head local_pages;
@@ -718,18 +718,17 @@ do {									\
 	__ret;								\
 })
 
+#define remove_parent(p)	list_del_init(&(p)->sibling)
+#define add_parent(p, parent)	list_add_tail(&(p)->sibling,&(parent)->children)
+
 #define REMOVE_LINKS(p) do {				\
-	(p)->next_task->prev_task = (p)->prev_task;	\
-	(p)->prev_task->next_task = (p)->next_task;	\
-	list_del_init(&(p)->sibling);			\
+	list_del_init(&(p)->tasks);			\
+	remove_parent(p);				\
 	} while (0)
 
-#define SET_LINKS(p) do {					\
-	(p)->next_task = &init_task;				\
-	(p)->prev_task = init_task.prev_task;			\
-	init_task.prev_task->next_task = (p);			\
-	init_task.prev_task = (p);				\
-	list_add_tail(&(p)->sibling,&(p)->parent->children);	\
+#define SET_LINKS(p) do {				\
+	list_add_tail(&(p)->tasks,&init_task.tasks);	\
+	add_parent(p, (p)->parent);			\
 	} while (0)
 
 static inline struct task_struct *eldest_child(struct task_struct *p)
@@ -756,8 +755,11 @@ static inline struct task_struct *younger_sibling(struct task_struct *p)
 	return list_entry(p->sibling.next,struct task_struct,sibling);
 }
 
+#define next_task(p)	list_entry((p)->tasks.next, struct task_struct, tasks)
+#define prev_task(p)	list_entry((p)->tasks.prev, struct task_struct, tasks)
+
 #define for_each_task(p) \
-	for (p = &init_task ; (p = p->next_task) != &init_task ; )
+	for (p = &init_task ; (p = next_task(p)) != &init_task ; )
 
 #define for_each_thread(task) \
 	for (task = next_thread(current) ; task != current ; task = next_thread(task))

kernel/exit.c

@@ -612,9 +612,9 @@ asmlinkage long sys_wait4(pid_t pid,unsigned int * stat_addr, int options, struc
 				retval = p->pid;
 				if (p->real_parent != p->parent) {
 					write_lock_irq(&tasklist_lock);
-					REMOVE_LINKS(p);
+					remove_parent(p);
 					p->parent = p->real_parent;
-					SET_LINKS(p);
+					add_parent(p, p->parent);
 					do_notify_parent(p, SIGCHLD);
 					write_unlock_irq(&tasklist_lock);
 				} else