[RFC][PATCH v2] irq_work: Drop cmpxchg result

[RFC][PATCH v2] irq_work: Drop cmpxchg result

[Sergio Aguirre]

This solves this compilation warning:

kernel/irq_work.c: In function 'irq_work_run':
kernel/irq_work.c:148: warning: value computed is not used

Signed-off-by: Sergio Aguirre <saaguirre@ti.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
---

Changelog:
v2 - Keep ignoring the cmpxchg return value, as pointed
     out by Peter Zijlstra, and update patch subject/description

v1 - Initial version
     (found here: https://patchwork.kernel.org/patch/328662/)

 kernel/irq_work.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index f16763f..90f8819 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -145,7 +145,9 @@ void irq_work_run(void)
 		 * Clear the BUSY bit and return to the free state if
 		 * no-one else claimed it meanwhile.
 		 */
-		cmpxchg(&entry->next, next_flags(NULL, IRQ_WORK_BUSY), NULL);
+		(void)cmpxchg(&entry->next,
+			      next_flags(NULL, IRQ_WORK_BUSY),
+			      NULL);
 	}
 }
 EXPORT_SYMBOL_GPL(irq_work_run);
-- 
1.7.0.4

Re: [RFC][PATCH v2] irq_work: Drop cmpxchg result

[Eric Dumazet]

Le mardi 16 novembre 2010 à 12:02 -0600, Sergio Aguirre a écrit :
> This solves this compilation warning:
> 
> kernel/irq_work.c: In function 'irq_work_run':
> kernel/irq_work.c:148: warning: value computed is not used

Just curious, what is your compiler version ?

Thanks

RE: [RFC][PATCH v2] irq_work: Drop cmpxchg result

[Aguirre, Sergio]

> -----Original Message-----
> From: Eric Dumazet [mailto:eric.dumazet@gmail.com]
> Sent: Tuesday, November 16, 2010 12:17 PM
> To: Aguirre, Sergio
> Cc: LKML; Huang Ying; Martin Schwidefsky; Ingo Molnar; Kyle McMartin;
> Peter Zijlstra
> Subject: Re: [RFC][PATCH v2] irq_work: Drop cmpxchg result
> 
> Le mardi 16 novembre 2010 à 12:02 -0600, Sergio Aguirre a écrit :
> > This solves this compilation warning:
> >
> > kernel/irq_work.c: In function 'irq_work_run':
> > kernel/irq_work.c:148: warning: value computed is not used
> 
> Just curious, what is your compiler version ?

I'm using a Code Sourcery ARM toolchain, and compiling for TI OMAP2+ chips (armv7-a)

# arm-none-linux-gnueabi-gcc --version
arm-none-linux-gnueabi-gcc (Sourcery G++ Lite 2010q1-202) 4.4.1
Copyright (C) 2009 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Regards,
Sergio

> 
> Thanks
> 

Re: [RFC][PATCH v2] irq_work: Drop cmpxchg result

[Peter Zijlstra]

On Tue, 2010-11-16 at 12:02 -0600, Sergio Aguirre wrote:
> This solves this compilation warning:
> 
> kernel/irq_work.c: In function 'irq_work_run':
> kernel/irq_work.c:148: warning: value computed is not used
> 
Thanks!

[tip:perf/urgent] irq_work: Drop cmpxchg() result

[tip-bot for Sergio Aguirre]

Commit-ID:  94e8ba728640dc01375a14e337f3b892bfacbeeb
Gitweb:     http://git.kernel.org/tip/94e8ba728640dc01375a14e337f3b892bfacbeeb
Author:     Sergio Aguirre <saaguirre@ti.com>
AuthorDate: Tue, 16 Nov 2010 12:02:47 -0600
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 18 Nov 2010 13:18:47 +0100

irq_work: Drop cmpxchg() result

The compiler warned us about:

 kernel/irq_work.c: In function 'irq_work_run':
 kernel/irq_work.c:148: warning: value computed is not used

Dropping the cmpxchg() result is indeed weird, but correct -
so annotate away the warning.

Signed-off-by: Sergio Aguirre <saaguirre@ti.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1289930567-17828-1-git-send-email-saaguirre@ti.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/irq_work.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index f16763f..90f8819 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -145,7 +145,9 @@ void irq_work_run(void)
 		 * Clear the BUSY bit and return to the free state if
 		 * no-one else claimed it meanwhile.
 		 */
-		cmpxchg(&entry->next, next_flags(NULL, IRQ_WORK_BUSY), NULL);
+		(void)cmpxchg(&entry->next,
+			      next_flags(NULL, IRQ_WORK_BUSY),
+			      NULL);
 	}
 }
 EXPORT_SYMBOL_GPL(irq_work_run);