Re: [PATCH] iommu: replace single-char identifiers in macros

[Robin Murphy]

On 03/06/2019 14:29, Qian Cai wrote:
> On Mon, 2019-06-03 at 14:07 +0100, Robin Murphy wrote:
> > On 03/06/2019 13:59, Qian Cai wrote:
> > > There are a few macros in IOMMU have single-char identifiers make the
> > > code hard to read and debug. Replace them with meaningful names.
> > >
> > > Suggested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > > Signed-off-by: Qian Cai <cai@xxxxxx>
> > > ---
> > >  Â include/linux/dmar.h | 14 ++++++++------
> > >  Â 1 file changed, 8 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/include/linux/dmar.h b/include/linux/dmar.h
> > > index f8af1d770520..eb634912f475 100644
> > > --- a/include/linux/dmar.h
> > > +++ b/include/linux/dmar.h
> > > @@ -104,12 +104,14 @@ static inline bool dmar_rcu_check(void)
> > >    
> > >  Â #define	dmar_rcu_dereference(p)	rcu_dereference_check((p),
> > > dmar_rcu_check())
> > >    
> > > -#define	for_each_dev_scope(a, c, p, d)	\
> > > -	for ((p) = 0; ((d) = (p) < (c) ? dmar_rcu_dereference((a)[(p)].dev)
> > > : \
> > > -			NULL, (p) < (c)); (p)++)
> > > -
> > > -#define	for_each_active_dev_scope(a, c, p, d)	\
> > > -	for_each_dev_scope((a), (c), (p), (d))	if (!(d)) { continue;
> > > } else
> > > +#define for_each_dev_scope(devs, cnt, i, tmp)				
> > > \
> > > +	for ((i) = 0; ((tmp) = (i) < (cnt) ?				
> > > \
> >
> > Given that "tmp" actually appears to be some sort of device cursor, I'm
> > not sure that that naming really achieves the stated goal of clarity :/
>
> "tmp" is used in the callers everywhere though, although I suppose something
> like "tmp_dev" can be used if you prefer.

I don't have any preference, I'm just questioning the assertion in the 
commit message - as a reader not intimately familiar with this code, 
"tmp" is honestly no more meaningful than "d" was.

Robin.