sched/headers: Move task-stack related APIs from <linux/sched.h> to <linux/sched/task_stack.h>

Split out the task->stack related functionality, which is not really
part of the core scheduler APIs.

Only keep task_thread_info() because it's used by sched.h.

Update the code that uses those facilities.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/mips/kernel/smp-cps.c

@@ -11,7 +11,7 @@
 #include <linux/delay.h>
 #include <linux/io.h>
 #include <linux/irqchip/mips-gic.h>
-#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
 #include <linux/sched/hotplug.h>
 #include <linux/slab.h>
 #include <linux/smp.h>

arch/mips/sibyte/sb1250/smp.c

@@ -21,7 +21,7 @@
 #include <linux/interrupt.h>
 #include <linux/smp.h>
 #include <linux/kernel_stat.h>
-#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
 
 #include <asm/mmu_context.h>
 #include <asm/io.h>

include/linux/sched.h

@@ -1450,6 +1450,15 @@ union thread_union {
 	unsigned long stack[THREAD_SIZE/sizeof(long)];
 };
 
+#ifdef CONFIG_THREAD_INFO_IN_TASK
+static inline struct thread_info *task_thread_info(struct task_struct *task)
+{
+	return &task->thread_info;
+}
+#elif !defined(__HAVE_THREAD_FUNCTIONS)
+# define task_thread_info(task)	((struct thread_info *)(task)->stack)
+#endif
+
 #ifndef __HAVE_ARCH_KSTACK_END
 static inline int kstack_end(void *addr)
 {
@@ -1540,112 +1549,6 @@ static inline void task_unlock(struct task_struct *p)
 	spin_unlock(&p->alloc_lock);
 }
 
-#ifdef CONFIG_THREAD_INFO_IN_TASK
-
-static inline struct thread_info *task_thread_info(struct task_struct *task)
-{
-	return &task->thread_info;
-}
-
-/*
- * When accessing the stack of a non-current task that might exit, use
- * try_get_task_stack() instead.  task_stack_page will return a pointer
- * that could get freed out from under you.
- */
-static inline void *task_stack_page(const struct task_struct *task)
-{
-	return task->stack;
-}
-
-#define setup_thread_stack(new,old)	do { } while(0)
-
-static inline unsigned long *end_of_stack(const struct task_struct *task)
-{
-	return task->stack;
-}
-
-#elif !defined(__HAVE_THREAD_FUNCTIONS)
-
-#define task_thread_info(task)	((struct thread_info *)(task)->stack)
-#define task_stack_page(task)	((void *)(task)->stack)
-
-static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org)
-{
-	*task_thread_info(p) = *task_thread_info(org);
-	task_thread_info(p)->task = p;
-}
-
-/*
- * Return the address of the last usable long on the stack.
- *
- * When the stack grows down, this is just above the thread
- * info struct. Going any lower will corrupt the threadinfo.
- *
- * When the stack grows up, this is the highest address.
- * Beyond that position, we corrupt data on the next page.
- */
-static inline unsigned long *end_of_stack(struct task_struct *p)
-{
-#ifdef CONFIG_STACK_GROWSUP
-	return (unsigned long *)((unsigned long)task_thread_info(p) + THREAD_SIZE) - 1;
-#else
-	return (unsigned long *)(task_thread_info(p) + 1);
-#endif
-}
-
-#endif
-
-#ifdef CONFIG_THREAD_INFO_IN_TASK
-static inline void *try_get_task_stack(struct task_struct *tsk)
-{
-	return atomic_inc_not_zero(&tsk->stack_refcount) ?
-		task_stack_page(tsk) : NULL;
-}
-
-extern void put_task_stack(struct task_struct *tsk);
-#else
-static inline void *try_get_task_stack(struct task_struct *tsk)
-{
-	return task_stack_page(tsk);
-}
-
-static inline void put_task_stack(struct task_struct *tsk) {}
-#endif
-
-#define task_stack_end_corrupted(task) \
-		(*(end_of_stack(task)) != STACK_END_MAGIC)
-
-static inline int object_is_on_stack(void *obj)
-{
-	void *stack = task_stack_page(current);
-
-	return (obj >= stack) && (obj < (stack + THREAD_SIZE));
-}
-
-extern void thread_stack_cache_init(void);
-
-#ifdef CONFIG_DEBUG_STACK_USAGE
-static inline unsigned long stack_not_used(struct task_struct *p)
-{
-	unsigned long *n = end_of_stack(p);
-
-	do { 	/* Skip over canary */
-# ifdef CONFIG_STACK_GROWSUP
-		n--;
-# else
-		n++;
-# endif
-	} while (!*n);
-
-# ifdef CONFIG_STACK_GROWSUP
-	return (unsigned long)end_of_stack(p) - (unsigned long)n;
-# else
-	return (unsigned long)n - (unsigned long)end_of_stack(p);
-# endif
-}
-#endif
-extern void set_task_stack_end_magic(struct task_struct *tsk);
-
 /* set thread flags in other task's structures
  * - see asm/thread_info.h for TIF_xxxx flags available
  */

include/linux/sched/task_stack.h

@@ -1,7 +1,111 @@
 #ifndef _LINUX_SCHED_TASK_STACK_H
 #define _LINUX_SCHED_TASK_STACK_H
 
+/*
+ * task->stack (kernel stack) handling interfaces:
+ */
+
 #include <linux/sched.h>
 #include <linux/magic.h>
 
+#ifdef CONFIG_THREAD_INFO_IN_TASK
+
+/*
+ * When accessing the stack of a non-current task that might exit, use
+ * try_get_task_stack() instead.  task_stack_page will return a pointer
+ * that could get freed out from under you.
+ */
+static inline void *task_stack_page(const struct task_struct *task)
+{
+	return task->stack;
+}
+
+#define setup_thread_stack(new,old)	do { } while(0)
+
+static inline unsigned long *end_of_stack(const struct task_struct *task)
+{
+	return task->stack;
+}
+
+#elif !defined(__HAVE_THREAD_FUNCTIONS)
+
+#define task_stack_page(task)	((void *)(task)->stack)
+
+static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org)
+{
+	*task_thread_info(p) = *task_thread_info(org);
+	task_thread_info(p)->task = p;
+}
+
+/*
+ * Return the address of the last usable long on the stack.
+ *
+ * When the stack grows down, this is just above the thread
+ * info struct. Going any lower will corrupt the threadinfo.
+ *
+ * When the stack grows up, this is the highest address.
+ * Beyond that position, we corrupt data on the next page.
+ */
+static inline unsigned long *end_of_stack(struct task_struct *p)
+{
+#ifdef CONFIG_STACK_GROWSUP
+	return (unsigned long *)((unsigned long)task_thread_info(p) + THREAD_SIZE) - 1;
+#else
+	return (unsigned long *)(task_thread_info(p) + 1);
+#endif
+}
+
+#endif
+
+#ifdef CONFIG_THREAD_INFO_IN_TASK
+static inline void *try_get_task_stack(struct task_struct *tsk)
+{
+	return atomic_inc_not_zero(&tsk->stack_refcount) ?
+		task_stack_page(tsk) : NULL;
+}
+
+extern void put_task_stack(struct task_struct *tsk);
+#else
+static inline void *try_get_task_stack(struct task_struct *tsk)
+{
+	return task_stack_page(tsk);
+}
+
+static inline void put_task_stack(struct task_struct *tsk) {}
+#endif
+
+#define task_stack_end_corrupted(task) \
+		(*(end_of_stack(task)) != STACK_END_MAGIC)
+
+static inline int object_is_on_stack(void *obj)
+{
+	void *stack = task_stack_page(current);
+
+	return (obj >= stack) && (obj < (stack + THREAD_SIZE));
+}
+
+extern void thread_stack_cache_init(void);
+
+#ifdef CONFIG_DEBUG_STACK_USAGE
+static inline unsigned long stack_not_used(struct task_struct *p)
+{
+	unsigned long *n = end_of_stack(p);
+
+	do { 	/* Skip over canary */
+# ifdef CONFIG_STACK_GROWSUP
+		n--;
+# else
+		n++;
+# endif
+	} while (!*n);
+
+# ifdef CONFIG_STACK_GROWSUP
+	return (unsigned long)end_of_stack(p) - (unsigned long)n;
+# else
+	return (unsigned long)n - (unsigned long)end_of_stack(p);
+# endif
+}
+#endif
+extern void set_task_stack_end_magic(struct task_struct *tsk);
+
 #endif /* _LINUX_SCHED_TASK_STACK_H */