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

[Matthew Wilcox]

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.

> > -	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.
>