Hi,
What do you think about this? The new file (vm86_mask.h) could actually be

embedded completely in processor-flags.h, but I went for what I believe is

the safer approach.
This has been compile tested on x86_32 and x86_64 defconfig.
Vegard
From: Vegard Nossum <vegard.nossum@gmail.com>

Date: Tue, 27 May 2008 21:38:35 +0200

Subject: [PATCH] x86: break mutual header inclusion
This breaks up the mutual inclusion between headers ptrace.h and vm86.h

by moving what's needed by both files into a new (minimal) file

vm86_mask.h.
We also move #include lines to the top.
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>

---

 include/asm-x86/ptrace.h    |   10 +++-------

 include/asm-x86/vm86.h      |    9 ++-------

 include/asm-x86/vm86_mask.h |   12 ++++++++++++

 3 files changed, 17 insertions(+), 14 deletions(-)

 create mode 100644 include/asm-x86/vm86_mask.h
diff --git a/include/asm-x86/ptrace.h b/include/asm-x86/ptrace.h

index 9f922b0..7ba799d 100644

--- a/include/asm-x86/ptrace.h

+++ b/include/asm-x86/ptrace.h

@@ -2,8 +2,10 @@

 #define _ASM_X86_PTRACE_H
 #include <linux/compiler.h>	/* For __user */

+#include <asm/ds.h>		/* the DS BTS struct is used for ptrace too */

+#include <asm/segment.h>

 #include <asm/ptrace-abi.h>

-

+#include <asm/vm86_mask.h>
 #ifndef __ASSEMBLY__
@@ -55,9 +57,6 @@ struct pt_regs {

 	unsigned long ss;

 };
-#include <asm/vm86.h>

-#include <asm/segment.h>

-

 #endif /* __KERNEL__ */
 #else /* __i386__ */

@@ -127,9 +126,6 @@ struct pt_regs {
 #ifdef __KERNEL__
-/* the DS BTS struct is used for ptrace as well */

-#include <asm/ds.h>

-

 struct task_struct;
 extern void ptrace_bts_take_timestamp(struct task_struct *, enum bts_qualifier);

diff --git a/include/asm-x86/vm86.h b/include/asm-x86/vm86.h

index 074b357..ad8d143 100644

--- a/include/asm-x86/vm86.h

+++ b/include/asm-x86/vm86.h

@@ -13,12 +13,8 @@

  */
 #include <asm/processor-flag...
[ message continues ]

Breaking the mutual header inclusion is appreciated, but some comments 
Moving #include's out of an #ifdef __KERNEL__ can (and does here) break

our userspace headers.
Running "make headers_check" after touching anything under include/ is
Do we need a new header for this or can it go into processor-flags.h ?
cu

Adrian
-- 
       "Is there not promise of rain?" Ling Tan asked suddenly out

        of the darkness. There had been need of rain for many days.

       "Only a promise," Lao Er said.

                                       Pearl S. Buck - Dragon Seed
--

Hi!
Ah, that's true. My mistake.
  CHECK   include/asm/ptrace.h

[...]/usr/include/asm/ptrace.h requires asm/ds.h, which does not exist

in exported headers
What do you reckon is better here, to put #ifdef __KERNEL__ around the

whole of ds.h and export it, or put #ifdef __KERNEL__ around the

#include in ptrace.h? It feels wasteful to put it around the whole

ds.h, since what is the point in exporting an empty file? On the other

hand, it makes much more sense to put it there than in the "caller" in

order to avoid the duplication of #ifdef __KERNEL__. So unless you

prefer otherwise, I will choose the former (to export ds.h as well).
I hope you agree with the idea of moving the #include line to the top

of the file, however?
Thanks for the tip, that is very useful. I didn't realize I should use
It can go in there, yes. I will do that in the re-worked (hopefully

correct) patch.
This business of breaking cycles is a bit nasty. There are very many

traps to fall into, very many setups to break, and very little support

from the tools to help you get it right (though with 'make

headers_check' I am a little better off).
Thanks for the help :-)
Vegard
--

"The animistic metaphor of the bug that maliciously sneaked in while

the programmer was not looking is intellectually dishonest as it

disguises that the error is the programmer's own creation."

	-- E. W. Dijkstra, EWD1036

--

Our userspace headers are an API, and offering empty previsously

unexported headers to userspace sounds like the worse choice to me.
cu

Adrian
-- 
       "Is there not promise of rain?" Ling Tan asked suddenly out

        of the darkness. There had been need of rain for many days.

       "Only a promise," Lao Er said.

                                       Pearl S. Buck - Dragon Seed
--