linux-kernel - Re: [PATCH v2 2/2] add check for pointers with _

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Message-ID: <68fbc211c59b9_10e910034@dwillia2-mobl4.notmuch>
Date: Fri, 24 Oct 2025 11:14:41 -0700
From: <dan.j.williams@...el.com>
To: Joe Perches <joe@...ches.com>, Ally Heev <allyheev@...il.com>, "Dwaipayan
 Ray" <dwaipayanray1@...il.com>, Lukas Bulwahn <lukas.bulwahn@...il.com>,
	Jonathan Corbet <corbet@....net>, Andy Whitcroft <apw@...onical.com>
CC: <workflows@...r.kernel.org>, <linux-doc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Dan Carpenter <dan.carpenter@...aro.org>,
	David Hunter <david.hunter.linux@...il.com>, Shuah Khan
	<skhan@...uxfoundation.org>, Viresh Kumar <vireshk@...nel.org>, "Nishanth
 Menon" <nm@...com>, Stephen Boyd <sboyd@...nel.org>, linux-pm
	<linux-pm@...r.kernel.org>, <dan.j.williams@...el.com>
Subject: Re: [PATCH v2 2/2] add check for pointers with __free attribute
 initialized to NULL

Joe Perches wrote:
> On Fri, 2025-10-24 at 22:59 +0530, Ally Heev wrote:
> > pointers with __free attribute initialized to NULL
> > pose potential cleanup issues [1] when a function uses
> > interdependent variables with cleanup attributes
> > 
> > Link: https://docs.kernel.org/core-api/cleanup.html [1]
> > Link: https://lore.kernel.org/all/68f7b830ec21a_10e910070@dwillia2-mobl4.notmuch/
> > Suggested-by: Dan Williams <dan.j.williams@...el.com>
> > Signed-off-by: Ally Heev <allyheev@...il.com>
> []
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> []
> > @@ -7728,6 +7728,12 @@ sub process {
> >  			ERROR("UNINITIALIZED_PTR_WITH_FREE",
> >  			      "pointer '$1' with __free attribute should be initialized\n" . $herecurr);
> >  		}
> > +
> > +# check for pointers with __free attribute initialized to NULL
> > +		while ($line =~ /\*\s*($Ident)\s+$FreeAttribute\s*=\s*NULL\b/g) {
> > +			WARN("NULL_INITIALIZED_PTR_WITH_FREE",
> > +			      "pointer '$1' with __free attribute should be initialized to a non-NULL address\n" . $herecurr);
> > +		}
> >  	}
> 
> I think this a poor idea as almost all the instances where this
> initialization is done are fine.
> 
> And there are a lot of them.
> 
> $ git grep -P '\b__free\b.*=\s*NULL\s*;' | wc -l
> 490

That is significant. ...but you did say "almost" above. What about
moving this from WARN level to CHK level?

With that change you can add:

Acked-by: Dan Williams <dan.j.williams@...el.com>