From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Tissoires Subject: Re: [PATCH v3 1/8] Input: synaptics-rmi4: Use of_get_child_by_name() instead of of_find_node_by_name() Date: Mon, 18 Jul 2016 16:48:20 +0200 Message-ID: <20160718144820.GL4663@mail.corp.redhat.com> References: <1468476488-7935-1-git-send-email-aduggan@synaptics.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Received: from mx1.redhat.com ([209.132.183.28]:48211 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751455AbcGROsb (ORCPT ); Mon, 18 Jul 2016 10:48:31 -0400 Content-Disposition: inline In-Reply-To: <1468476488-7935-1-git-send-email-aduggan@synaptics.com> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Andrew Duggan Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Dmitry Torokhov , Linus Walleij , Jiri Kosina , Vincent Huang , Nick Dyer , Chris Healy On Jul 13 2016 or thereabouts, Andrew Duggan wrote: > Calling of_find_node_by_name() assumes that the caller has incremented > the refcount of the of_node being passed in. Currently, the caller is > not incrementing the refcount of the of_node which results in the node > being prematurely freed when of_find_node_by_name() calls of_node_put() > on it. Instead use of_get_child_by_name() which does not call put on the > of_node. There are 2 other differences in using of_get_child_by_name() in place of of_find_node_by_name(). One is that now we are following the OF tree while the spinlock is not held. I think it's fine in our case. The other difference is that the returned of_node has not been called of_node_get() on it. I am not 100% sure, but I think it might be good to call of_node_get() on the of node here, and in remove call of_node_put(), just to be sure we don't use the of_node while it has been freed. Cheers, Benjamin > > Signed-off-by: Andrew Duggan > --- > drivers/input/rmi4/rmi_bus.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/input/rmi4/rmi_bus.c b/drivers/input/rmi4/rmi_bus.c > index b368b05..253df96 100644 > --- a/drivers/input/rmi4/rmi_bus.c > +++ b/drivers/input/rmi4/rmi_bus.c > @@ -157,11 +157,11 @@ static int rmi_function_match(struct device *dev, struct device_driver *drv) > static void rmi_function_of_probe(struct rmi_function *fn) > { > char of_name[9]; > + struct device_node *node = fn->rmi_dev->xport->dev->of_node; > > snprintf(of_name, sizeof(of_name), "rmi4-f%02x", > fn->fd.function_number); > - fn->dev.of_node = of_find_node_by_name( > - fn->rmi_dev->xport->dev->of_node, of_name); > + fn->dev.of_node = of_get_child_by_name(node, of_name); > } > #else > static inline void rmi_function_of_probe(struct rmi_function *fn) > -- > 2.5.0 >