On Mon, 17 Jul 2023 at 11:03, Paul E. McKenney <paulmck@xxxxxxxxxx> wrote:
>
> +// Dummy structure for srcu_notifier_head.
> +struct srcu_usage {
> + char srcuu_dummy;
> +};
> +
> +#define __SRCU_USAGE_INIT(name) { .srcuu_dummy = 0, }
You really should be able to just do
struct srcu_usage { };
#define __SRCU_USAGE_INIT(name) { }
which is something we've done for ages for spinlocks in
include/linux/spinlock_types_up.h
because while we had a gcc bug wrt empty structures, that was ages ago
(ie "gcc-2.x").
See commit a1365647022e ("[PATCH] remove gcc-2 checks") from 2006.
So we've already had these kinds of empty dummy structs for literally
over a decade in active use. Exactly so that you can avoid having to
use #ifdef's etc, and can just always assume you have a spinlock, even
if it doesn't generate any code or any data overhead.
Linus
