[PATCH] add bottom_half.h

With CONFIG_SMP=n:

drivers/input/ff-memless.c:384: warning: implicit declaration of function 'local_bh_disable'
drivers/input/ff-memless.c:393: warning: implicit declaration of function 'local_bh_enable'

Really linux/spinlock.h should include linux/interrupt.h. But interrupt.h
includes sched.h which will need spinlock.h.

So the patch breaks the _bh declarations out into a separate header and
includes it in both interrupt.h and spinlock.h.

Cc: "Randy.Dunlap" <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/bottom_half.h

···
+#ifndef _LINUX_BH_H
+#define _LINUX_BH_H
+
+extern void local_bh_disable(void);
+extern void __local_bh_enable(void);
+extern void _local_bh_enable(void);
+extern void local_bh_enable(void);
+extern void local_bh_enable_ip(unsigned long ip);
+
+#endif /* _LINUX_BH_H */

include/linux/interrupt.h

···
 #include <linux/hardirq.h>
 #include <linux/sched.h>
 #include <linux/irqflags.h>
+#include <linux/bottom_half.h>
 #include <asm/atomic.h>
 #include <asm/ptrace.h>
 #include <asm/system.h>
···
 }
 #define save_and_cli(x)	save_and_cli(&x)
 #endif /* CONFIG_SMP */
-
-extern void local_bh_disable(void);
-extern void __local_bh_enable(void);
-extern void _local_bh_enable(void);
-extern void local_bh_enable(void);
-extern void local_bh_enable_ip(unsigned long ip);
 
 /* PLEASE, avoid to allocate new softirqs, if you need not _really_ high
    frequency threaded job scheduling. For almost all the purposes

include/linux/spinlock.h

···
 #include <linux/thread_info.h>
 #include <linux/kernel.h>
 #include <linux/stringify.h>
+#include <linux/bottom_half.h>
 
 #include <asm/system.h>