Re: [PATCH] refcount: always allow checked forms

From: David Sterba <dsterba@suse.cz>
To: Mark Rutland <mark.rutland@arm.com>
Cc: dsterba@suse.cz, linux-kernel@vger.kernel.org,
	Will Deacon <will.deacon@arm.com>,
	Kees Cook <keescook@chromium.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH] refcount: always allow checked forms
Date: Wed, 11 Jul 2018 19:37:05 +0200	[thread overview]
Message-ID: <20180711173705.j6qfye4rq3ccmdyq@twin.jikos.cz> (raw)
In-Reply-To: <20180711054946.wdkfoou6kt2a2vml@salmiak>

On Wed, Jul 11, 2018 at 06:49:46AM +0100, Mark Rutland wrote:
> > > Dave pointed out that it would be useful to be able to opt-in to full checks
> > > regardless of CONFIG_REFCOUNT_FULL, so that we can simplify callsites where we
> > > always want checks. I've spotted a few of these in code which is still awaiting
> > > conversion.
> > 
> > The motivation was code like
> > 
> > 	WARN_ON(refcount_read(&ref));
> > 	if (refcount_dec_and_test(&ref)) { ... }
> > 
> > so the warning is redundant for REFCOUNT_FULL, but I'm going to use the
> > _checked versions everywhere the performance of refcounts is not
> > critical.
> 
> If you will have conversion patches, do you want to pick this up as the start
> of a series?

The patches where I'd use the enhanced refcounts are nice-to-have and I
don't have an ETA so it would be better if the patch gets merged
independently. Thanks.