Re: [PATCH 5/5] mm: add the __must_check attribute to {gfn,mfn}_add()

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

On Wed, Feb 14, 2024 at 02:42:46PM +0100, Jan Beulich wrote:
> On 14.02.2024 11:37, Roger Pau Monne wrote:
> > It's not obvious from the function itself whether the incremented value 
> > will be
> 
> s/the function itself/just the function name/ ?
> 
> > stored in the parameter, or returned to the caller.  That has leads to bugs 
> > in
> > the past as callers assume the incremented value is stored in the parameter.
> 
> ... callers may assume ... ?
> 
> > --- a/xen/include/xen/mm-frame.h
> > +++ b/xen/include/xen/mm-frame.h
> > @@ -23,7 +23,7 @@ TYPE_SAFE(unsigned long, mfn);
> >  #undef mfn_x
> >  #endif
> >  
> > -static inline mfn_t mfn_add(mfn_t mfn, unsigned long i)
> > +static inline mfn_t __must_check mfn_add(mfn_t mfn, unsigned long i)
> >  {
> >      return _mfn(mfn_x(mfn) + i);
> >  }
> > @@ -62,7 +62,7 @@ TYPE_SAFE(unsigned long, gfn);
> >  #undef gfn_x
> >  #endif
> >  
> > -static inline gfn_t gfn_add(gfn_t gfn, unsigned long i)
> > +static inline gfn_t __must_check gfn_add(gfn_t gfn, unsigned long i)
> >  {
> >      return _gfn(gfn_x(gfn) + i);
> >  }
> 
> What about dfn_add() (in xen/iommu.h)?

Oh, didn't spot that one.

Thanks, Roger.