Re: [Qemu-devel] [PATCH 1/3] rng-random: NULL check not needed before g_free()

[Amos Kong <akong@redhat.com>]

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.