On Thu, Jun 22, 2017 at 09:26:44AM +0200, Ingo Molnar wrote:
>
> * Paul E. McKenney <[email protected]> wrote:
>
> > On Wed, Jun 21, 2017 at 11:57:28PM +0200, Arnd Bergmann wrote:
> > > Without CONFIG_SMP, we get a harmless warning about
> > > an unused variable:
> > >
> > > kernel/cpu.c: In function 'boot_cpu_state_init':
> > > kernel/cpu.c:1778:6: error: unused variable 'cpu'
> > > [-Werror=unused-variable]
> > >
> > > This reworks the function to have the declaration inside
> > > of the #ifdef.
> > >
> > > Fixes: faeb334286b7 ("rcu: Migrate callbacks earlier in the CPU-offline
> > > timeline")
> > > Signed-off-by: Arnd Bergmann <[email protected]>
> >
> > I simply added a __maybe_unused in 6441c656acde ("rcu: Migrate callbacks
> > earlier in the CPU-offline timeline") in my -rcu tree. However, your
> > approach does have the advantage of complaining if the code using that
> > variable is removed.
> >
> > So, would you be OK with my folding your approach into my commit with
> > attribution?
>
> Also, note that __maybe_unused can be dangerous: it can hide a build warning
> where
> there's a _real_ unused variable bug now or due to future changes, causing a
> real
> runtime bug.
>
> So I think we should consider it a syntactic construct to avoid.
I will review the ones in RCU.
Thanx, Paul
