RE: [PATCH] x86: bitops: fix build regression

[David Laight]

From: Brian Gerst
> Sent: 07 May 2020 07:18
...
> > --- a/arch/x86/include/asm/bitops.h
> > +++ b/arch/x86/include/asm/bitops.h
> > @@ -54,7 +54,7 @@ arch_set_bit(long nr, volatile unsigned long *addr)
> >         if (__builtin_constant_p(nr)) {
> >                 asm volatile(LOCK_PREFIX "orb %1,%0"
> >                         : CONST_MASK_ADDR(nr, addr)
> > -                       : "iq" (CONST_MASK(nr) & 0xff)
> > +                       : "iq" ((u8)(CONST_MASK(nr) & 0xff))
> 
> I think a better fix would be to make CONST_MASK() return a u8 value
> rather than have to cast on every use.

Or assign to a local variable - then it doesn't matter how
the value is actually calculated. So:
			u8 mask = CONST_MASK(nr);
			asm volatile(LOCK_PREFIX "orb %1,%0"
				: CONST_MASK_ADDR(nr, addr)
				: "iq" mask

	David

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