sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h>

We are going to split <linux/sched/task_stack.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/task_stack.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

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>

kernel/events/callchain.c

@@ -11,6 +11,8 @@
 
 #include <linux/perf_event.h>
 #include <linux/slab.h>
+#include <linux/sched/task_stack.h>
+
 #include "internal.h"
 
 struct callchain_cpus_entries {

kernel/exit.c

@@ -10,6 +10,7 @@
 #include <linux/sched/mm.h>
 #include <linux/sched/stat.h>
 #include <linux/sched/task.h>
+#include <linux/sched/task_stack.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/capability.h>

kernel/fork.c

@@ -19,6 +19,7 @@
 #include <linux/sched/numa_balancing.h>
 #include <linux/sched/stat.h>
 #include <linux/sched/task.h>
+#include <linux/sched/task_stack.h>
 #include <linux/rtmutex.h>
 #include <linux/init.h>
 #include <linux/unistd.h>

kernel/printk/printk.c

@@ -47,6 +47,7 @@
 #include <linux/uio.h>
 #include <linux/sched/clock.h>
 #include <linux/sched/debug.h>
+#include <linux/sched/task_stack.h>
 
 #include <linux/uaccess.h>
 #include <asm/sections.h>

kernel/sched/sched.h

@@ -15,6 +15,7 @@
 #include <linux/sched/debug.h>
 #include <linux/sched/hotplug.h>
 #include <linux/sched/task.h>
+#include <linux/sched/task_stack.h>
 
 #include <linux/u64_stats_sync.h>
 #include <linux/kernel_stat.h>

kernel/seccomp.c

@@ -18,6 +18,7 @@
 #include <linux/compat.h>
 #include <linux/coredump.h>
 #include <linux/sched.h>
+#include <linux/sched/task_stack.h>
 #include <linux/seccomp.h>
 #include <linux/slab.h>
 #include <linux/syscalls.h>

kernel/signal.c

@@ -17,6 +17,7 @@
 #include <linux/sched/user.h>
 #include <linux/sched/debug.h>
 #include <linux/sched/task.h>
+#include <linux/sched/task_stack.h>
 #include <linux/fs.h>
 #include <linux/tty.h>
 #include <linux/binfmts.h>

kernel/trace/trace_stack.c

@@ -2,6 +2,7 @@
  * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
  *
  */
+#include <linux/sched/task_stack.h>
 #include <linux/stacktrace.h>
 #include <linux/kallsyms.h>
 #include <linux/seq_file.h>