[PATCH/RFC] headers: drop 2 #included headers from <linux/interrupt.h>

[Randy Dunlap]

From: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>

It seems that <linux/interrupt.h> does not need <linux/linkage.h>
nor <linux/preempt.h>.  8 kernels builds are successful without
these 2 headers (allmodconfig, allyesconfig, allnoconfig, and
tinyconfig on both i386 and x86_64).

<linux/interrupt.h> is #included 3875 times in 4.16-rc1, so this
reduces #include processing of these 2 files by a total of 7750 times.

Since I only tested x86 builds, this needs to be tested on other
$ARCHes as well.

Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
---

Does anyone know or see why <linux/interrupt.h> needs <linux/linkage.h> or
<linux/preempt.h>?  There are no direct uses in <linux/interrupt.h> AFAICT.

 include/linux/interrupt.h |    2 --
 1 file changed, 2 deletions(-)

--- lnx-416-rc1.orig/include/linux/interrupt.h
+++ lnx-416-rc1/include/linux/interrupt.h
@@ -4,9 +4,7 @@
 #define _LINUX_INTERRUPT_H
 
 #include <linux/kernel.h>
-#include <linux/linkage.h>
 #include <linux/bitops.h>
-#include <linux/preempt.h>
 #include <linux/cpumask.h>
 #include <linux/irqreturn.h>
 #include <linux/irqnr.h>