From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Ellerman Subject: Re: [PATCH v2 3/7] dt/powerpc/powernv: Use of_get_child_by_name to get a named child. Date: Mon, 17 Sep 2012 12:07:48 +1000 Message-ID: <1347847668.28674.3.camel@concordia> References: <1347610743-20189-1-git-send-email-srinivas.kandagatla@st.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1347610743-20189-1-git-send-email-srinivas.kandagatla-qxv4g6HH51o@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Srinivas KANDAGATLA Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org List-Id: devicetree@vger.kernel.org On Fri, 2012-09-14 at 09:19 +0100, Srinivas KANDAGATLA wrote: > From: Srinivas Kandagatla > > As follow-up to "dt: introduce of_get_child_by_name to get child node by > name." patch, This patch removes some of the code duplication in the > driver by replacing it with of_get_child_by_name instead. > > Signed-off-by: Srinivas Kandagatla > --- > arch/powerpc/platforms/powernv/opal.c | 6 ++---- > 1 files changed, 2 insertions(+), 4 deletions(-) > > diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c > index aaa0dba..6dfb8af 100644 > --- a/arch/powerpc/platforms/powernv/opal.c > +++ b/arch/powerpc/platforms/powernv/opal.c > @@ -294,11 +294,9 @@ static int __init opal_init(void) > consoles = of_node_get(opal_node); > > /* Register serial ports */ > - for_each_child_of_node(consoles, np) { > - if (strcmp(np->name, "serial")) > - continue; > + np = of_get_child_by_name(consoles, "serial"); > + if (np) > of_platform_device_create(np, NULL, NULL); > - } > of_node_put(consoles); You've introduced a refcounting bug here. The return value of of_get_child_by_name() has its refcount elevated (via of_node_get()), so you have to drop that reference with of_node_put(). The old code was safe because it only used np inside the loop, and the loop logic deals with dropping the refcount for you. And yes of_platform_device_create() takes a reference for itself. cheers