Re: [Xen-devel] [PATCH v3 1/2] atomic: add atomic_and operations

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Mon, Feb 24, 2020 at 10:02:53AM +0000, Julien Grall wrote:
> Hi Roger,
> 
> The logic for Arm64 and Arm32 looks good to me. I just have one question
> below.
> 
> On 24/02/2020 08:43, Roger Pau Monne wrote:
> > To x86 and Arm. This performs an atomic AND operation against an
> > atomic_t variable with the provided mask.
> > 
> > Requested-by: Jan Beulich <jbeulich@xxxxxxxx>
> > Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> > ---
> >   xen/include/asm-arm/arm32/atomic.h | 17 +++++++++++++++++
> >   xen/include/asm-arm/arm64/atomic.h | 14 ++++++++++++++
> >   xen/include/asm-x86/atomic.h       |  8 ++++++++
> >   3 files changed, 39 insertions(+)
> > 
> > diff --git a/xen/include/asm-arm/arm32/atomic.h 
> > b/xen/include/asm-arm/arm32/atomic.h
> > index c03eb684cd..4637381bcc 100644
> > --- a/xen/include/asm-arm/arm32/atomic.h
> > +++ b/xen/include/asm-arm/arm32/atomic.h
> > @@ -96,6 +96,23 @@ static inline int atomic_sub_return(int i, atomic_t *v)
> >     return result;
> >   }
> > +static inline void atomic_and(unsigned int m, atomic_t *v)
> 
> All the atomic helpers have taken a signed int so far because the counter is
> an int. Any reason to diverge from that?

Since this is not an arithmetic operation I felt unsigned int was a
more suitable type to describe a bitmask: it felt weird to pass a
bitmask with type int, because signedness doesn't make sense when
referring to a mask.

Thanks, Roger.

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