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

From: hpa
Date: Thu May 07 2020 - 04:39:02 EST


On May 7, 2020 1:35:01 AM PDT, David Laight <David.Laight@xxxxxxxxxx> wrote:
>From: hpa@xxxxxxxxx
>> Sent: 07 May 2020 08:59
>> On May 7, 2020 12:44:44 AM PDT, David Laight
><David.Laight@xxxxxxxxxx> wrote:
>> >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
>> >
>> >-
>> >Registered Address Lakeside, Bramley Road, Mount Farm, Milton
>Keynes,
>> >MK1 1PT, UK
>> >Registration No: 1397386 (Wales)
>>
>> "const u8" please...
>
>Why, just a waste of disk space.
>
> David
>
>-
>Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes,
>MK1 1PT, UK
>Registration No: 1397386 (Wales)

Descriptive.
--
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