[patch 4/8] irq code: Add coherence test for PREEMPT_ACTIVE

[patch 4/8] irq code: Add coherence test for PREEMPT_ACTIVE

[blaisorblade]

After porting this fixlet to UML:

http://linux.bkbits.net:8080/linux-2.5/cset@41791ab52lfMuF2i3V-eTIGRBbDYKQ

, I've also added a warning which should refuse compilation with insane values
for PREEMPT_ACTIVE... maybe we should simply move PREEMPT_ACTIVE out of
architectures using GENERIC_IRQS.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
---

 linux-2.6.git-paolo/include/linux/hardirq.h |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletion(-)

diff -puN include/linux/hardirq.h~coherence-test-preempt-active include/linux/hardirq.h
--- linux-2.6.git/include/linux/hardirq.h~coherence-test-preempt-active	2005-05-25 00:59:11.000000000 +0200
+++ linux-2.6.git-paolo/include/linux/hardirq.h	2005-05-25 00:59:26.000000000 +0200
@@ -43,13 +43,17 @@
 #define __IRQ_MASK(x)	((1UL << (x))-1)
 
 #define PREEMPT_MASK	(__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
-#define HARDIRQ_MASK	(__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
 #define SOFTIRQ_MASK	(__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
+#define HARDIRQ_MASK	(__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
 
 #define PREEMPT_OFFSET	(1UL << PREEMPT_SHIFT)
 #define SOFTIRQ_OFFSET	(1UL << SOFTIRQ_SHIFT)
 #define HARDIRQ_OFFSET	(1UL << HARDIRQ_SHIFT)
 
+#if PREEMPT_ACTIVE < (1 << (HARDIRQ_SHIFT + HARDIRQ_BITS))
+#error PREEMPT_ACTIVE is too low!
+#endif
+
 #define hardirq_count()	(preempt_count() & HARDIRQ_MASK)
 #define softirq_count()	(preempt_count() & SOFTIRQ_MASK)
 #define irq_count()	(preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK))
_

Re: [patch 4/8] irq code: Add coherence test for PREEMPT_ACTIVE

[Blaisorblade]

On Friday 27 May 2005 02:38, blaisorblade@yahoo.it wrote:
> After porting this fixlet to UML:
>
> http://linux.bkbits.net:8080/linux-2.5/cset@41791ab52lfMuF2i3V-eTIGRBbDYKQ
>
> , I've also added a warning which should refuse compilation with insane
> values for PREEMPT_ACTIVE... maybe we should simply move PREEMPT_ACTIVE out
> of architectures using GENERIC_IRQS.
Ok, a grep shows that possible culprits (i.e. giving success to
grep GENERIC_HARDIRQS arch/*/Kconfig, and using 0x4000000 as PREEMPT_ACTIVE, 
as given by grep PREEMPT_ACTIVE include/asm-*/thread_info.h) are (at a first 
glance): frv, sh, sh64.

After a bit of checking, I also verified if they had overriden the value of 
HARDIRQ_BITS. Which they haven't (it seems it's defined exactly where 
CONFIG_HARDIRQS is not used, i.e. nobody is using the ability to override it 
currently).

This was not a very deep investigation, however, so feel free to verify this 
better.
-- 
Paolo Giarrusso, aka Blaisorblade
Skype user "PaoloGiarrusso"
Linux registered user n. 292729
http://www.user-mode-linux.org/~blaisorblade

	

	
		
___________________________________ 
Yahoo! Mail: gratis 1GB per i messaggi e allegati da 10MB 
http://mail.yahoo.it

Re: [patch 4/8] irq code: Add coherence test for PREEMPT_ACTIVE

[Paul Mundt]

[-- Attachment #1: Type: text/plain, Size: 2056 bytes --]

On Fri, May 27, 2005 at 03:06:09AM +0200, Blaisorblade wrote:
> On Friday 27 May 2005 02:38, blaisorblade@yahoo.it wrote:
> > After porting this fixlet to UML:
> >
> > http://linux.bkbits.net:8080/linux-2.5/cset@41791ab52lfMuF2i3V-eTIGRBbDYKQ
> >
> > , I've also added a warning which should refuse compilation with insane
> > values for PREEMPT_ACTIVE... maybe we should simply move PREEMPT_ACTIVE out
> > of architectures using GENERIC_IRQS.
> Ok, a grep shows that possible culprits (i.e. giving success to
> grep GENERIC_HARDIRQS arch/*/Kconfig, and using 0x4000000 as PREEMPT_ACTIVE, 
> as given by grep PREEMPT_ACTIVE include/asm-*/thread_info.h) are (at a first 
> glance): frv, sh, sh64.
> 
Yeah, that's bogus for sh and sh64 anyways, this should do it.

It would be nice to move PRREMPT_ACTIVE so it isn't per-arch anymore,
there's not many users that use a different value (at least for the ones
using generic hardirqs, ia64 seems to be the only one?).

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

include/asm-sh/thread_info.h: needs update
include/asm-sh64/thread_info.h: needs update
Index: include/asm-sh/thread_info.h
===================================================================
--- 3ac9a34948049bff79a2b2ce49c0a3c84e35a748/include/asm-sh/thread_info.h  (mode:100644)
+++ uncommitted/include/asm-sh/thread_info.h  (mode:100644)
@@ -27,7 +27,7 @@
 
 #endif
 
-#define PREEMPT_ACTIVE		0x4000000
+#define PREEMPT_ACTIVE		0x10000000
 
 /*
  * macros/functions for gaining access to the thread information structure
Index: include/asm-sh64/thread_info.h
===================================================================
--- 3ac9a34948049bff79a2b2ce49c0a3c84e35a748/include/asm-sh64/thread_info.h  (mode:100644)
+++ uncommitted/include/asm-sh64/thread_info.h  (mode:100644)
@@ -73,7 +73,7 @@
 
 #define THREAD_SIZE  8192
 
-#define PREEMPT_ACTIVE		0x4000000
+#define PREEMPT_ACTIVE		0x10000000
 
 /* thread information flags */
 #define TIF_SYSCALL_TRACE	0	/* syscall trace active */

[-- Attachment #2: Type: application/pgp-signature, Size: 189 bytes --]

Re: [patch 4/8] irq code: Add coherence test for PREEMPT_ACTIVE

[Blaisorblade]

On Friday 27 May 2005 05:31, Paul Mundt wrote:
> On Fri, May 27, 2005 at 03:06:09AM +0200, Blaisorblade wrote:
> > On Friday 27 May 2005 02:38, blaisorblade@yahoo.it wrote:

> > Ok, a grep shows that possible culprits (i.e. giving success to
> > grep GENERIC_HARDIRQS arch/*/Kconfig, and using 0x4000000 as
> > PREEMPT_ACTIVE, as given by grep PREEMPT_ACTIVE
> > include/asm-*/thread_info.h) are (at a first glance): frv, sh, sh64.

> Yeah, that's bogus for sh and sh64 anyways, this should do it.

> It would be nice to move PRREMPT_ACTIVE so it isn't per-arch anymore,
> there's not many users that use a different value (at least for the ones
> using generic hardirqs, ia64 seems to be the only one?).

Then in the generic headers
#ifndef PREEMPT_ACTIVE
#define PREEMPT_ACTIVE <the right value>
#else
<do the above coherence test>
#endif
Would be ok, right?
-- 
Paolo Giarrusso, aka Blaisorblade
Skype user "PaoloGiarrusso"
Linux registered user n. 292729
http://www.user-mode-linux.org/~blaisorblade

	

	
		
___________________________________ 
Yahoo! Mail: gratis 1GB per i messaggi e allegati da 10MB 
http://mail.yahoo.it

Re: [patch 4/8] irq code: Add coherence test for PREEMPT_ACTIVE

[David Howells]

Blaisorblade <blaisorblade@yahoo.it> wrote:

> Ok, a grep shows that possible culprits (i.e. giving success to
> grep GENERIC_HARDIRQS arch/*/Kconfig, and using 0x4000000 as PREEMPT_ACTIVE, 
> as given by grep PREEMPT_ACTIVE include/asm-*/thread_info.h) are (at a first 
> glance): frv, sh, sh64.

For FRV that's simply because it got copied from the parent arch along with
other stuff. Feel free to move it... Do you want me to make you up a patch to
do so?

David

Re: [patch 4/8] irq code: Add coherence test for PREEMPT_ACTIVE

[Blaisorblade]

On Friday 27 May 2005 15:33, David Howells wrote:
> Blaisorblade <blaisorblade@yahoo.it> wrote:
> > Ok, a grep shows that possible culprits (i.e. giving success to
> > grep GENERIC_HARDIRQS arch/*/Kconfig, and using 0x4000000 as
> > PREEMPT_ACTIVE, as given by grep PREEMPT_ACTIVE
> > include/asm-*/thread_info.h) are (at a first glance): frv, sh, sh64.
>
> For FRV that's simply because it got copied from the parent arch along with
> other stuff. Feel free to move it... Do you want me to make you up a patch
> to do so?
Sorry but fix that yourself, otherwise you get a chance I'll forget since I'm 
quite busy.

Thanks a lot for attention.
-- 
Paolo Giarrusso, aka Blaisorblade
Skype user "PaoloGiarrusso"
Linux registered user n. 292729
http://www.user-mode-linux.org/~blaisorblade

		
___________________________________ 
Yahoo! Messenger: chiamate gratuite in tutto il mondo 
http://it.beta.messenger.yahoo.com