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    On Thu, Jun 22, 2017 at 09:26:44AM +0200, Ingo Molnar wrote:
    >
    > * Paul E. McKenney <paulmck@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 <arnd@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.

    I will review the ones in RCU.

    Thanx, Paul

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