Re: [PATCH] acpi: fix pwr_btn_event_pending build error

Kirill A. Shutemov
2012-07-22T00:07:59Z

On Sat, Jul 21, 2012 at 04:37:14PM -0700, Paul E. McKenney wrote:
> On Sun, Jul 22, 2012 at 12:52:43AM +0300, Kirill A. Shutemov wrote:
> > On Sat, Jul 21, 2012 at 02:41:56PM -0700, Paul E. McKenney wrote:
> > > Hello!
> > >
> > > A recent build for KVM on x86 resulted in the following build error:
> > >
> > > drivers/acpi/sleep.c:60:13: warning: ‘pwr_btn_event_pending’ defined but not
> > > +used [-Wunused-variable]
> > >
> > > This patch silences this error.
> > >
> > > Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
> > >
> > > diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
> > > index 8856102..18347aa 100644
> > > --- a/drivers/acpi/sleep.c
> > > +++ b/drivers/acpi/sleep.c
> > > @@ -57,7 +57,9 @@ MODULE_PARM_DESC(gts, "Enable evaluation of _GTS on suspend.");
> > > MODULE_PARM_DESC(bfs, "Enable evaluation of _BFS on resume".);
> > >
> > > static u8 sleep_states[ACPI_S_STATE_COUNT];
> > > +#ifdef CONFIG_ACPI_SLEEP
> > > static bool pwr_btn_event_pending;
> > > +#endif /* #ifdef CONFIG_ACPI_SLEEP */
> >
> > __maybe_unused ?
>
> Are the compiler and linker smart enough to get rid of the storage in
> case it really isn't used? (Not that the storage for a bool is worth
> worrying about, but...)

GCC with optimization enabled will get rid of the storage even without
__maybe_unused.

--
Kirill A. Shutemov