From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [patch 6/6] preempt: Make PREEMPT_ACTIVE generic
Date: Wed, 18 Sep 2013 12:48:35 +0200
Message-ID: <20130918104835.GH9326@twins.programming.kicks-ass.net>
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 <20130917182350.449685712@linutronix.de>
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To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>, linux-arch@vger.kernel.org, Linus Torvalds <torvalds@linux-foundation.org>, Andi Kleen <ak@linux.intel.com>, Peter Anvin <hpa@zytor.com>, Mike Galbraith <bitbucket@online.de>, Arjan van de Ven <arjan@linux.intel.com>, Frederic Weisbecker <fweisbec@gmail.com>

On Tue, Sep 17, 2013 at 06:53:09PM -0000, Thomas Gleixner wrote:
> No point in having this bit defined by architecture.
>=20
> Index: linux-2.6/include/linux/preempt_mask.h
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> --- linux-2.6.orig/include/linux/preempt_mask.h
> +++ linux-2.6/include/linux/preempt_mask.h
> @@ -17,10 +17,11 @@
>   * there are a few palaeontologic drivers which reenable interrupts =
in
>   * the handler, so we need more than one bit here.
>   *
> - * PREEMPT_MASK: 0x000000ff
> - * SOFTIRQ_MASK: 0x0000ff00
> - * HARDIRQ_MASK: 0x000f0000
> - *     NMI_MASK: 0x00100000
> + * PREEMPT_MASK:	0x000000ff
> + * SOFTIRQ_MASK:	0x0000ff00
> + * HARDIRQ_MASK:	0x000f0000
> + *     NMI_MASK:	0x00100000
> + * PREEMPT_ACTIVE:	0x00200000
>   */
>  #define PREEMPT_BITS	8
>  #define SOFTIRQ_BITS	8
> @@ -46,15 +47,9 @@
> =20
>  #define SOFTIRQ_DISABLE_OFFSET	(2 * SOFTIRQ_OFFSET)
> =20
> -#ifndef PREEMPT_ACTIVE
>  #define PREEMPT_ACTIVE_BITS	1
>  #define PREEMPT_ACTIVE_SHIFT	(NMI_SHIFT + NMI_BITS)
>  #define PREEMPT_ACTIVE	(__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_A=
CTIVE_SHIFT)
> -#endif
> -
> -#if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS))
> -#error PREEMPT_ACTIVE is too low!
> -#endif
> =20
>  #define hardirq_count()	(preempt_count() & HARDIRQ_MASK)
>  #define softirq_count()	(preempt_count() & SOFTIRQ_MASK)

I get:

 init/init_task.c:26:4: error: =E2=80=98PREEMPT_ACTIVE=E2=80=99 undecla=
red here (not in a function)

Because for some obscure reason sched.h doesn't actually include enough=
=2E

The below cures things:

--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -22,6 +22,7 @@ struct sched_param {
 #include <linux/errno.h>
 #include <linux/nodemask.h>
 #include <linux/mm_types.h>
+#include <linux/preempt_mask.h>
=20
 #include <asm/page.h>
 #include <asm/ptrace.h>