linux-next: percpu tree build warning

linux-next: percpu tree build warning

[Stephen Rothwell]

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Hi all,

Today's linux-next build (powerpc ppc64_defconfig) produced this warning:

drivers/net/loopback.c: In function 'loopback_get_stats':
drivers/net/loopback.c:109: warning: initialization discards qualifiers from pointer target type

The line in question is:

	lb_stats = per_cpu_ptr(pcpu_lstats, i);

Where "lb_stats" and "pcpu_lstats" are both "const struct pcpu_lstats
*".  I guess this is because of __verify_pcpu_ptr().

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/

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Re: linux-next: percpu tree build warning

[Christoph Lameter]

On Thu, 12 Nov 2009, Stephen Rothwell wrote:

> Hi all,
>
> Today's linux-next build (powerpc ppc64_defconfig) produced this warning:
>
> drivers/net/loopback.c: In function 'loopback_get_stats':
> drivers/net/loopback.c:109: warning: initialization discards qualifiers from pointer target type
>
> The line in question is:
>
> 	lb_stats = per_cpu_ptr(pcpu_lstats, i);
>
> Where "lb_stats" and "pcpu_lstats" are both "const struct pcpu_lstats
> *".  I guess this is because of __verify_pcpu_ptr().

hmm... pcpu_lstats needs to be correctly qualified I guess.

[PATCH percpu#for-next] percpu: remove compile warnings caused by __verify_pcpu_ptr()

[Tejun Heo]

If percpu pointer is const, __verify_pcpu_ptr() triggers warnings like
the following.

 drivers/net/loopback.c: In function 'loopback_get_stats':
 drivers/net/loopback.c:109: warning: initialization discards qualifiers from pointer target type

Fix it by adding const to the verification target pointer used in
__verify_pcpu_ptr().

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
---
Sorry about the delay.  Patch committed to percpu#for-next.

Thanks.

 include/linux/percpu-defs.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
index 1fa36eb..68567c0 100644
--- a/include/linux/percpu-defs.h
+++ b/include/linux/percpu-defs.h
@@ -24,7 +24,7 @@
  * input parameter is a percpu pointer.
  */
 #define __verify_pcpu_ptr(ptr)	do {					\
-	void __percpu *__vpp_verify = (typeof(ptr))NULL;		\
+	const void __percpu *__vpp_verify = (typeof(ptr))NULL;		\
 	(void)__vpp_verify;						\
 } while (0)

-- 
1.6.4.2