Re: [PATCH v2] sched: Fix compiler warnings

[Guenter Roeck]

On 06/25/2014 12:14 AM, Uwe Kleine-König wrote:
> On Tue, Jun 24, 2014 at 06:05:29PM -0700, Guenter Roeck wrote:
> > Commit 143e1e28cb (sched: Rework sched_domain topology definition)
> > introduced a number of functions with a return value of 'const int'.
> > gcc doesn't know what to do with that and, if the kernel is compiled
> > with W=1, complains with the following warnings whenever sched.h
> > is included.
> >
> > include/linux/sched.h:875:25: warning:
> > 	type qualifiers ignored on function return type
> > include/linux/sched.h:882:25: warning:
> > 	type qualifiers ignored on function return type
> > include/linux/sched.h:889:25: warning:
> > 	type qualifiers ignored on function return type
> > include/linux/sched.h:1002:21: warning:
> > 	type qualifiers ignored on function return type
> >
> > Commits fb2aa855 (sched, ARM: Create a dedicated scheduler topology table)
> > and 607b45e9a (sched, powerpc: Create a dedicated topology table) introduce
> > the same warning in the arm and powerpc code.
> >
> > Drop 'const' from the function declarations to fix the problem.
> >
> > The fix for all three patches has to be applied together to avoid
> > compilation failures for the affected architectures.
> >
> > Cc: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> > Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> > Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> > Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
> > Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> > ---
> > v2: Fix problem in all affected architectures with a single patch
> >      to avoid compilation errors.
> >
> >   arch/arm/kernel/topology.c | 2 +-
> >   arch/powerpc/kernel/smp.c  | 2 +-
> >   include/linux/sched.h      | 8 ++++----
> >   3 files changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
> > index 9d85318..e35d880 100644
> > --- a/arch/arm/kernel/topology.c
> > +++ b/arch/arm/kernel/topology.c
> > @@ -275,7 +275,7 @@ void store_cpu_topology(unsigned int cpuid)
> >   		cpu_topology[cpuid].socket_id, mpidr);
> >   }
> >
> > -static inline const int cpu_corepower_flags(void)
> > +static inline int cpu_corepower_flags(void)
> >   {
> >   	return SD_SHARE_PKG_RESOURCES  | SD_SHARE_POWERDOMAIN;
> >   }
> Maybe the author's intention was:
>
> 	static inline int cpu_corepower_flags(void) __attribute__((const));
>
> ?
> This specifies that the function has no side effects and the return value
> only depends on the (here non-existing) function arguments.

Possibly, but either I am missing something or this doesn't compile.

Guenter


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