From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <1347847668.28674.3.camel@concordia> Subject: Re: [PATCH v2 3/7] dt/powerpc/powernv: Use of_get_child_by_name to get a named child. From: Michael Ellerman To: Srinivas KANDAGATLA Date: Mon, 17 Sep 2012 12:07:48 +1000 In-Reply-To: <1347610743-20189-1-git-send-email-srinivas.kandagatla@st.com> References: <1347610743-20189-1-git-send-email-srinivas.kandagatla@st.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Cc: devicetree-discuss@lists.ozlabs.org, robherring2@gmail.com, linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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