Re: [PATCH v2 12/12] s390/percpu: Rework to simplify percpu_entry() and percpu_exit()

On Fri, Sep 18, 2026 at 11:40:21AM +0100, Mark Rutland wrote:
> On Fri, Sep 18, 2026 at 10:48:42AM +0200, Heiko Carstens wrote:
> > +#define __PCPU_AGRK(regptr, regpcp, regoff)					\
> > +	"	agrk	" regptr "," regpcp "," regoff "\n"
> > +
> > +#define __PCPU_BEGIN(lcreg, lcoff, regpcp, regoff, regptr)			\
> > +	__PCPU_MVIY_REGS(lcreg, regpcp, regoff)					\
> > +	__PCPU_LG(regoff, lcoff)						\
> > +	__PCPU_AGRK(regptr, regpcp, regoff)
> 
> Since percpu_exit() relies on regptr being regoff + 1, maybe it's worth
> having a check here to verify that? Perhaps in __PCPU_MVIY_REGS() with
> the uniqueness check.
> 
> Hopefully that never goes wrong, but catching a violation at build time
> might save some future pain.

Yes, that makes sense. Especially considering that there was already a
previous bug which could have been caught at build time.

Thanks a lot for taking a look!