Re: [PATCH] mm: Use BUG_ON instead of if condition followed by BUG

[Julia Lawall]

On Thu, 25 Nov 2021, Matthew Wilcox wrote:

> On Wed, Nov 24, 2021 at 01:23:42PM +0000, Matthew Wilcox wrote:
> > On Wed, Nov 24, 2021 at 03:08:49AM +0000, cgel.zte@xxxxxxxxx wrote:
> > > From: chiminghao <chi.minghao@xxxxxxxxxx>
> > >
> > > Fix the following coccinelle report:
> > > ./mm/memory_hotplug.c:2210:2-5:
> > > WARNING  Use BUG_ON instead of if condition followed by BUG.
> >
> > What coccinelle script is reporting this?
>
> Maybe I found it?
>
> scripts/coccinelle/misc/bugon.cocci:msg="WARNING: Use BUG_ON instead of if condition followed by BUG.\nPlease make sure the condition has no side effects (see conditional BUG_ON definition in include/asm-generic/bug.h)"
>
> Julia, Michal, can we delete this script, please?  It's being abused.

OK

julia

>
> > > -	if (try_remove_memory(start, size))
> > > -		BUG();
> > > +	BUG_ON(try_remove_memory(start, size));
> >
> > I really, really, really do not like this.  For functions with
> > side-effects, this is bad style.  If it's a pure predicate, then
> > sure, but this is bad.
> >
>