* Paul E. McKenney <paul...@linux.vnet.ibm.com> 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 <a...@arndb.de>
>
> 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.
Thanks,
Ingo
