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

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Message-Id: <20211124142751.e48cdcc3aea9e0ef899f4347@linux-foundation.org>
Date:   Wed, 24 Nov 2021 14:27:51 -0800
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     cgel.zte@...il.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, chiminghao <chi.minghao@....com.cn>,
        Zeal Robot <zealci@....com.cn>
Subject: Re: [PATCH] mm: Use BUG_ON instead of if condition followed by BUG

On Wed, 24 Nov 2021 13:23:42 +0000 Matthew Wilcox <willy@...radead.org> wrote:

> On Wed, Nov 24, 2021 at 03:08:49AM +0000, cgel.zte@...il.com wrote:
> > From: chiminghao <chi.minghao@....com.cn>
> > 
> > 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?
> 
> > -	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.

I don't like it either.  Yes, BUG() is special but it's such dangerous
practice.  I'd vote to change coccinelle.