From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:56429)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <akong@redhat.com>) id 1XFDJm-0006B3-9k
	for qemu-devel@nongnu.org; Wed, 06 Aug 2014 22:20:44 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <akong@redhat.com>) id 1XFDJc-0000Fz-St
	for qemu-devel@nongnu.org; Wed, 06 Aug 2014 22:20:38 -0400
Received: from mx1.redhat.com ([209.132.183.28]:4095)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <akong@redhat.com>) id 1XFDJc-0000Fc-LG
	for qemu-devel@nongnu.org; Wed, 06 Aug 2014 22:20:28 -0400
Date: Thu, 7 Aug 2014 10:19:21 +0800
From: Amos Kong <akong@redhat.com>
Message-ID: <20140807021921.GA8109@z.redhat.com>
References: <1401480140-18653-1-git-send-email-ehabkost@redhat.com>
	<1401480140-18653-2-git-send-email-ehabkost@redhat.com>
	<87wqcz4k37.fsf@blackfin.pond.sub.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <87wqcz4k37.fsf@blackfin.pond.sub.org>
Subject: Re: [Qemu-devel] [PATCH 1/3] rng-random: NULL check not needed
 before g_free()
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Markus Armbruster <armbru@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>, Marcel Apfelbaum <marcel.a@redhat.com>, qemu-devel@nongnu.org, Luiz Capitulino <lcapitulino@redhat.com>, Anthony Liguori <aliguori@amazon.com>, Andreas =?iso-8859-1?Q?F=E4rber?= <afaerber@suse.de>

On Mon, Jun 02, 2014 at 01:38:52PM +0200, Markus Armbruster wrote:
> Eduardo Habkost <ehabkost@redhat.com> writes:
> 
> > g_free() is NULL-safe.
> >
> > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> > ---
> > Cc: Anthony Liguori <aliguori@amazon.com>
> > Cc: Luiz Capitulino <lcapitulino@redhat.com>
> > ---
> >  backends/rng-random.c | 5 +----
> >  1 file changed, 1 insertion(+), 4 deletions(-)
> >
> > diff --git a/backends/rng-random.c b/backends/rng-random.c
> > index 136499d..601d9dc 100644
> > --- a/backends/rng-random.c
> > +++ b/backends/rng-random.c
> > @@ -106,10 +106,7 @@ static void rng_random_set_filename(Object *obj, const char *filename,
> >          return;
> >      }
> >  
> > -    if (s->filename) {
> > -        g_free(s->filename);
> > -    }
> > -
> > +    g_free(s->filename);
> >      s->filename = g_strdup(filename);
> >  }
> 
> Reviewed-by: Markus Armbruster <armbru@redhat.com>
> 
> 
> Note there are a quite a few more instances of this anti-pattern.
> Coccinelle can find them, semantic patch appended.  Beware, it can throw
> away comments in the conditional, which is usually not what we want.
> 
> 
> @@
> expression E;
> @@
> -	if (E != NULL) {
> -	    g_free(E);
> -	}
> +       g_free(E);

[amos@z qemu]$ grep g_free -B 2 -r * |less

then try to search "/if.*NULL"

Not all can be found by this way, but many instances are found.

-- 
			Amos.