sched/headers: Simplify and clean up header usage in the scheduler

Do the following cleanups and simplifications:

 - sched/sched.h already includes <asm/paravirt.h>, so no need to
   include it in sched/core.c again.

 - order the <linux/sched/*.h> headers alphabetically

 - add all <linux/sched/*.h> headers to kernel/sched/sched.h

 - remove all unnecessary includes from the .c files that
   are already included in kernel/sched/sched.h.

Finally, make all scheduler .c files use a single common header:

  #include "sched.h"

... which now contains a union of the relied upon headers.

This makes the various .c files easier to read and easier to handle.

Cc: 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>

1 files changed, 2 insertions, 3 deletions

diff --git a/kernel/sched/idle_task.c b/kernel/sched/idle_task.c
index ec73680922f8..488222ac4651 100644
--- a/kernel/sched/idle_task.c
+++ b/kernel/sched/idle_task.c
@@ -1,12 +1,11 @@
 // SPDX-License-Identifier: GPL-2.0
-#include "sched.h"
-
 /*
  * idle-task scheduling class.
  *
- * (NOTE: these are not related to SCHED_IDLE tasks which are
+ * (NOTE: these are not related to SCHED_IDLE batch scheduling tasks which are
  *  handled in sched/fair.c)
  */
+#include "sched.h"
 
 #ifdef CONFIG_SMP
 static int