[PATCH 2/2] asm-generic: Don't warn that atomic_t is only 24 bit

[PATCH 2/2] asm-generic: Don't warn that atomic_t is only 24 bit

[Peter Fritzsche]

32-bit Sparc used to only allow usage of 24-bit of it's atomic_t type.
This was corrected with linux 2.6.3 when Keith M Wesolowski changed the
implementation to use the parisc approach of having an array of
spinlocks to protect the atomic_t.

These warnings were also removed from the sparc implementation when the
new implementation was merged in BKrev:402e4949VThdc6D3iaosSFUgabMfvw,
but the warning still remained in some other places without any
24-bit-only atomic_t implementation inside the kernel.

We should remove these warnings to allow users to rely on the full
32-bit range of atomic_t.

Signed-off-by: Peter Fritzsche <peter.fritzsche@gmx.de>
---
 This should correct the problem mentioned in http://lkml.org/lkml/2010/4/26/33

 include/asm-generic/atomic.h |    8 ++------
 1 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h
index c99c64d..345bfda 100644
--- a/include/asm-generic/atomic.h
+++ b/include/asm-generic/atomic.h
@@ -30,8 +30,7 @@
  * atomic_read - read atomic variable
  * @v: pointer of type atomic_t
  *
- * Atomically reads the value of @v.  Note that the guaranteed
- * useful range of an atomic_t is only 24 bits.
+ * Atomically reads the value of @v.
  */
 #define atomic_read(v)	((v)->counter)
 
@@ -40,8 +39,7 @@
  * @v: pointer of type atomic_t
  * @i: required value
  *
- * Atomically sets the value of @v to @i.  Note that the guaranteed
- * useful range of an atomic_t is only 24 bits.
+ * Atomically sets the value of @v to @i.
  */
 #define atomic_set(v, i) (((v)->counter) = (i))
 
@@ -53,7 +51,6 @@
  * @v: pointer of type atomic_t
  *
  * Atomically adds @i to @v and returns the result
- * Note that the guaranteed useful range of an atomic_t is only 24 bits.
  */
 static inline int atomic_add_return(int i, atomic_t *v)
 {
@@ -75,7 +72,6 @@ static inline int atomic_add_return(int i, atomic_t *v)
  * @v: pointer of type atomic_t
  *
  * Atomically subtracts @i from @v and returns the result
- * Note that the guaranteed useful range of an atomic_t is only 24 bits.
  */
 static inline int atomic_sub_return(int i, atomic_t *v)
 {
-- 
1.7.1

[PATCH 2/2] asm-generic: Don't warn that atomic_t is only 24 bit

[Peter Fritzsche]

32-bit Sparc used to only allow usage of 24-bit of it's atomic_t type.
This was corrected with linux 2.6.3 when Keith M Wesolowski changed the
implementation to use the parisc approach of having an array of
spinlocks to protect the atomic_t.

These warnings were also removed from the sparc implementation when the
new implementation was merged in BKrev:402e4949VThdc6D3iaosSFUgabMfvw,
but the warning still remained in some other places without any
24-bit-only atomic_t implementation inside the kernel.

We should remove these warnings to allow users to rely on the full
32-bit range of atomic_t.

Signed-off-by: Peter Fritzsche <peter.fritzsche@gmx.de>
---
 This should correct the problem mentioned in http://lkml.org/lkml/2010/4/26/33

 include/asm-generic/atomic.h |    8 ++------
 1 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h
index c99c64d..345bfda 100644
--- a/include/asm-generic/atomic.h
+++ b/include/asm-generic/atomic.h
@@ -30,8 +30,7 @@
  * atomic_read - read atomic variable
  * @v: pointer of type atomic_t
  *
- * Atomically reads the value of @v.  Note that the guaranteed
- * useful range of an atomic_t is only 24 bits.
+ * Atomically reads the value of @v.
  */
 #define atomic_read(v)	((v)->counter)
 
@@ -40,8 +39,7 @@
  * @v: pointer of type atomic_t
  * @i: required value
  *
- * Atomically sets the value of @v to @i.  Note that the guaranteed
- * useful range of an atomic_t is only 24 bits.
+ * Atomically sets the value of @v to @i.
  */
 #define atomic_set(v, i) (((v)->counter) = (i))
 
@@ -53,7 +51,6 @@
  * @v: pointer of type atomic_t
  *
  * Atomically adds @i to @v and returns the result
- * Note that the guaranteed useful range of an atomic_t is only 24 bits.
  */
 static inline int atomic_add_return(int i, atomic_t *v)
 {
@@ -75,7 +72,6 @@ static inline int atomic_add_return(int i, atomic_t *v)
  * @v: pointer of type atomic_t
  *
  * Atomically subtracts @i from @v and returns the result
- * Note that the guaranteed useful range of an atomic_t is only 24 bits.
  */
 static inline int atomic_sub_return(int i, atomic_t *v)
 {
-- 
1.7.1

Re: [PATCH 2/2] asm-generic: Don't warn that atomic_t is only 24 bit

[Arnd Bergmann]

On Wednesday 28 April 2010, Peter Fritzsche wrote:
> 32-bit Sparc used to only allow usage of 24-bit of it's atomic_t type.
> This was corrected with linux 2.6.3 when Keith M Wesolowski changed the
> implementation to use the parisc approach of having an array of
> spinlocks to protect the atomic_t.
> 
> These warnings were also removed from the sparc implementation when the
> new implementation was merged in BKrev:402e4949VThdc6D3iaosSFUgabMfvw,
> but the warning still remained in some other places without any
> 24-bit-only atomic_t implementation inside the kernel.
> 
> We should remove these warnings to allow users to rely on the full
> 32-bit range of atomic_t.
> 
> Signed-off-by: Peter Fritzsche <peter.fritzsche@gmx.de>

Acked-by: Arnd Bergmann <arnd@arndb.de>

Re: [PATCH 2/2] asm-generic: Don't warn that atomic_t is only 24 bit

[Mathieu Desnoyers]

* Arnd Bergmann (arnd@arndb.de) wrote:
> On Wednesday 28 April 2010, Peter Fritzsche wrote:
> > 32-bit Sparc used to only allow usage of 24-bit of it's atomic_t type.
> > This was corrected with linux 2.6.3 when Keith M Wesolowski changed the
> > implementation to use the parisc approach of having an array of
> > spinlocks to protect the atomic_t.
> > 
> > These warnings were also removed from the sparc implementation when the
> > new implementation was merged in BKrev:402e4949VThdc6D3iaosSFUgabMfvw,
> > but the warning still remained in some other places without any
> > 24-bit-only atomic_t implementation inside the kernel.
> > 
> > We should remove these warnings to allow users to rely on the full
> > 32-bit range of atomic_t.
> > 
> > Signed-off-by: Peter Fritzsche <peter.fritzsche@gmx.de>
> 
> Acked-by: Arnd Bergmann <arnd@arndb.de>

AFAIK that was the last architecture imposing limitations below 32 bits
on atomic_t.

Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>


-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com

Re: [PATCH 2/2] asm-generic: Don't warn that atomic_t is only 24 bit

[Mathieu Desnoyers]

* Arnd Bergmann (arnd@arndb.de) wrote:
> On Wednesday 28 April 2010, Peter Fritzsche wrote:
> > 32-bit Sparc used to only allow usage of 24-bit of it's atomic_t type.
> > This was corrected with linux 2.6.3 when Keith M Wesolowski changed the
> > implementation to use the parisc approach of having an array of
> > spinlocks to protect the atomic_t.
> > 
> > These warnings were also removed from the sparc implementation when the
> > new implementation was merged in BKrev:402e4949VThdc6D3iaosSFUgabMfvw,
> > but the warning still remained in some other places without any
> > 24-bit-only atomic_t implementation inside the kernel.
> > 
> > We should remove these warnings to allow users to rely on the full
> > 32-bit range of atomic_t.
> > 
> > Signed-off-by: Peter Fritzsche <peter.fritzsche@gmx.de>
> 
> Acked-by: Arnd Bergmann <arnd@arndb.de>

AFAIK that was the last architecture imposing limitations below 32 bits
on atomic_t.

Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>


-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com

Re: [PATCH 2/2] asm-generic: Don't warn that atomic_t is only 24 bit

[Jamie Lokier]

Mathieu Desnoyers wrote:
> * Arnd Bergmann (arnd@arndb.de) wrote:
> > On Wednesday 28 April 2010, Peter Fritzsche wrote:
> > > 32-bit Sparc used to only allow usage of 24-bit of it's atomic_t type.
> > > This was corrected with linux 2.6.3 when Keith M Wesolowski changed the
> > > implementation to use the parisc approach of having an array of
> > > spinlocks to protect the atomic_t.
> > > 
> > > These warnings were also removed from the sparc implementation when the
> > > new implementation was merged in BKrev:402e4949VThdc6D3iaosSFUgabMfvw,
> > > but the warning still remained in some other places without any
> > > 24-bit-only atomic_t implementation inside the kernel.
> > > 
> > > We should remove these warnings to allow users to rely on the full
> > > 32-bit range of atomic_t.
> > > 
> > > Signed-off-by: Peter Fritzsche <peter.fritzsche@gmx.de>
> > 
> > Acked-by: Arnd Bergmann <arnd@arndb.de>
> 
> AFAIK that was the last architecture imposing limitations below 32 bits
> on atomic_t.
> 
> Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

If the comment's getting removed, it should probably go from here too:

linux-2.6$ git grep '24' arch/*/include/*/atomic*
arch/mn10300/include/asm/atomic.h: * useful range of an atomic_t is only 24 bits
arch/mn10300/include/asm/atomic.h: * useful range of an atomic_t is only 24 bits
arch/mn10300/include/asm/atomic.h: * Note that the guaranteed useful range of an
arch/mn10300/include/asm/atomic.h: * Note that the guaranteed useful range of an

-- Jamie

Re: [PATCH 2/2] asm-generic: Don't warn that atomic_t is only 24 bit

[Mathieu Desnoyers]

* Jamie Lokier (jamie@shareable.org) wrote:
> Mathieu Desnoyers wrote:
> > * Arnd Bergmann (arnd@arndb.de) wrote:
> > > On Wednesday 28 April 2010, Peter Fritzsche wrote:
> > > > 32-bit Sparc used to only allow usage of 24-bit of it's atomic_t type.
> > > > This was corrected with linux 2.6.3 when Keith M Wesolowski changed the
> > > > implementation to use the parisc approach of having an array of
> > > > spinlocks to protect the atomic_t.
> > > > 
> > > > These warnings were also removed from the sparc implementation when the
> > > > new implementation was merged in BKrev:402e4949VThdc6D3iaosSFUgabMfvw,
> > > > but the warning still remained in some other places without any
> > > > 24-bit-only atomic_t implementation inside the kernel.
> > > > 
> > > > We should remove these warnings to allow users to rely on the full
> > > > 32-bit range of atomic_t.
> > > > 
> > > > Signed-off-by: Peter Fritzsche <peter.fritzsche@gmx.de>
> > > 
> > > Acked-by: Arnd Bergmann <arnd@arndb.de>
> > 
> > AFAIK that was the last architecture imposing limitations below 32 bits
> > on atomic_t.
> > 
> > Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> 
> If the comment's getting removed, it should probably go from here too:
> 
> linux-2.6$ git grep '24' arch/*/include/*/atomic*
> arch/mn10300/include/asm/atomic.h: * useful range of an atomic_t is only 24 bits
> arch/mn10300/include/asm/atomic.h: * useful range of an atomic_t is only 24 bits
> arch/mn10300/include/asm/atomic.h: * Note that the guaranteed useful range of an
> arch/mn10300/include/asm/atomic.h: * Note that the guaranteed useful range of an


How about simply replacing arch/mn10300/include/asm/atomic.h by:

arch/mn10300/include/asm/atomic.h:
#include <asm-generic/atomic.h>

?

This should have been done a while ago. They are almost the same, except for
added cmpxchg*_local() in the asm-generic version (which would benefit to
mn10300).

Thanks,

Mathieu

> 
> -- Jamie

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com

Re: [PATCH 2/2] asm-generic: Don't warn that atomic_t is only 24 bit

[Peter Fritzsche]

On Wednesday 28 April 2010 17:28:15 you wrote:

> If the comment's getting removed, it should probably go from here too:
> 
> linux-2.6$ git grep '24' arch/*/include/*/atomic*
> arch/mn10300/include/asm/atomic.h: * useful range of an atomic_t is only 24
> bits arch/mn10300/include/asm/atomic.h: * useful range of an atomic_t is
> only 24 bits arch/mn10300/include/asm/atomic.h: * Note that the guaranteed
> useful range of an arch/mn10300/include/asm/atomic.h: * Note that the
> guaranteed useful range of an

This is part one of the patch - already sent to the mn10300 people. Currently 
only got Acked reponses for both patches

Best regards,
	Peter Fritzsche

Re: [PATCH 2/2] asm-generic: Don't warn that atomic_t is only 24 bit

[Peter Fritzsche]

On Wednesday 28 April 2010 17:28:15 you wrote:

> If the comment's getting removed, it should probably go from here too:
> 
> linux-2.6$ git grep '24' arch/*/include/*/atomic*
> arch/mn10300/include/asm/atomic.h: * useful range of an atomic_t is only 24
> bits arch/mn10300/include/asm/atomic.h: * useful range of an atomic_t is
> only 24 bits arch/mn10300/include/asm/atomic.h: * Note that the guaranteed
> useful range of an arch/mn10300/include/asm/atomic.h: * Note that the
> guaranteed useful range of an

This is part one of the patch - already sent to the mn10300 people. Currently 
only got Acked reponses for both patches

Best regards,
	Peter Fritzsche

Re: [PATCH 2/2] asm-generic: Don't warn that atomic_t is only 24 bit

[David Howells]

Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:

> How about simply replacing arch/mn10300/include/asm/atomic.h by:
> 
> arch/mn10300/include/asm/atomic.h:
> #include <asm-generic/atomic.h>
> 
> ?
> 
> This should have been done a while ago. They are almost the same, except for
> added cmpxchg*_local() in the asm-generic version (which would benefit to
> mn10300).

Fine by me.

David

Re: [PATCH 2/2] asm-generic: Don't warn that atomic_t is only 24 bit

[Mathieu Desnoyers]

* David Howells (dhowells@redhat.com) wrote:
> Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
> 
> > How about simply replacing arch/mn10300/include/asm/atomic.h by:
> > 
> > arch/mn10300/include/asm/atomic.h:
> > #include <asm-generic/atomic.h>
> > 
> > ?
> > 
> > This should have been done a while ago. They are almost the same, except for
> > added cmpxchg*_local() in the asm-generic version (which would benefit to
> > mn10300).
> 
> Fine by me.

Then I'll let Peter Fritzsche deal with that. I don't want to conflict with his
current patches.

Thanks,

Mathieu

> 
> David

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com

Re: [PATCH 2/2] asm-generic: Don't warn that atomic_t is only 24 bit

[Mathieu Desnoyers]

* David Howells (dhowells@redhat.com) wrote:
> Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
> 
> > How about simply replacing arch/mn10300/include/asm/atomic.h by:
> > 
> > arch/mn10300/include/asm/atomic.h:
> > #include <asm-generic/atomic.h>
> > 
> > ?
> > 
> > This should have been done a while ago. They are almost the same, except for
> > added cmpxchg*_local() in the asm-generic version (which would benefit to
> > mn10300).
> 
> Fine by me.

Then I'll let Peter Fritzsche deal with that. I don't want to conflict with his
current patches.

Thanks,

Mathieu

> 
> David

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com

Re: [PATCH 2/2] asm-generic: Don't warn that atomic_t is only 24 bit

[Peter Fritzsche]

Mathieu Desnoyers wrote:
> * David Howells (dhowells@redhat.com) wrote:
> > Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
> > > How about simply replacing arch/mn10300/include/asm/atomic.h by:
> > > 
> > > arch/mn10300/include/asm/atomic.h:
> > > #include <asm-generic/atomic.h>
> > > 
> > > ?
> > > 
> > > This should have been done a while ago. They are almost the same,
> > > except for added cmpxchg*_local() in the asm-generic version (which
> > > would benefit to mn10300).
> > 
> > Fine by me.
> 
> Then I'll let Peter Fritzsche deal with that. I don't want to conflict with
> his current patches.

No, please go for your solution. It is the right thing to do and definitely 
better then my "remove some comments" patch. David Howells as MN10300 
maintainer already agreed to your suggestion. So I would like to recall my 
patch https://patchwork.kernel.org/patch/95651/ and let you submit a patch 
with your idea to the MN10300 maintainers which supersede my patch.

The state of https://patchwork.kernel.org/patch/95652/ hasn't been changed and 
I would love to see it merged by Arnd Bergmann in the next merge window.

Kind regards,
	Peter Fritzsche

Re: [PATCH 2/2] asm-generic: Don't warn that atomic_t is only 24 bit

[David Miller]

From: Peter Fritzsche <peter.fritzsche@gmx.de>
Date: Wed, 28 Apr 2010 13:10:36 +0200

> 32-bit Sparc used to only allow usage of 24-bit of it's atomic_t type.
> This was corrected with linux 2.6.3 when Keith M Wesolowski changed the
> implementation to use the parisc approach of having an array of
> spinlocks to protect the atomic_t.
> 
> These warnings were also removed from the sparc implementation when the
> new implementation was merged in BKrev:402e4949VThdc6D3iaosSFUgabMfvw,
> but the warning still remained in some other places without any
> 24-bit-only atomic_t implementation inside the kernel.
> 
> We should remove these warnings to allow users to rely on the full
> 32-bit range of atomic_t.
> 
> Signed-off-by: Peter Fritzsche <peter.fritzsche@gmx.de>

Acked-by: David S. Miller <davem@davemloft.net>