From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 407171C32 for ; Tue, 27 Aug 2024 01:40:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.187 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724722820; cv=none; b=LVcK9A2nupCGOB2VVn0zRYs6lYHbD73z/Syatall1G09u13tQ2FnnMxVTYqXIh487p3hreUYvW+6Vzp1mkoDP/u54bGcwz7d2CoNyq9Q2ChO4UE87NdBhm+wKwVLg0WAv8LCIP5+wHWU05sfcHU1xgsHbl5SSle7H6T4gFFFlk4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724722820; c=relaxed/simple; bh=CLznSmIb4/qMnWUWFCXh6Gtr5VWOk+gKcsrQXpmun94=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=k5pA5w7ZIYyilmza2EMBaIryANg5Y7zENJDCnne7QDiDbJZ3CBzvuzBnjUhzJQ1oNBiIy9fjg54GlnR5pZ9uA/f8iFFJRpsAK3INfVb553den06533jjwpbTCg8DXZylg6GTJIeKCXPxlvvRY7b48psze4Hf1SnX49pacZ2pM4o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.174]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Wt9Fm1yyvzyRDc; Tue, 27 Aug 2024 09:39:40 +0800 (CST) Received: from kwepemh500013.china.huawei.com (unknown [7.202.181.146]) by mail.maildlp.com (Postfix) with ESMTPS id 14645140257; Tue, 27 Aug 2024 09:40:09 +0800 (CST) Received: from [10.67.109.254] (10.67.109.254) by kwepemh500013.china.huawei.com (7.202.181.146) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Tue, 27 Aug 2024 09:40:08 +0800 Message-ID: <5d6debd0-1a02-f631-649e-26fb69e164e2@huawei.com> Date: Tue, 27 Aug 2024 09:40:07 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH -next 1/5] drm/rockchip: Use for_each_child_of_node_scoped() Content-Language: en-US To: Jonathan Cameron CC: , , , , , , , , , , , , , References: <20240823092053.3170445-1-ruanjinjie@huawei.com> <20240823092053.3170445-2-ruanjinjie@huawei.com> <20240823123203.00002aac@Huawei.com> From: Jinjie Ruan In-Reply-To: <20240823123203.00002aac@Huawei.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemh500013.china.huawei.com (7.202.181.146) On 2024/8/23 19:32, Jonathan Cameron wrote: > On Fri, 23 Aug 2024 17:20:49 +0800 > Jinjie Ruan wrote: > >> Avoids the need for manual cleanup of_node_put() in early exits >> from the loop. >> >> Signed-off-by: Jinjie Ruan > > There is more to do here, and looking at the code, I'm far from > sure it isn't releasing references it never had. > >> --- >> drivers/gpu/drm/rockchip/rockchip_lvds.c | 8 +++----- >> 1 file changed, 3 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/gpu/drm/rockchip/rockchip_lvds.c b/drivers/gpu/drm/rockchip/rockchip_lvds.c >> index 9a01aa450741..f5b3f18794dd 100644 >> --- a/drivers/gpu/drm/rockchip/rockchip_lvds.c >> +++ b/drivers/gpu/drm/rockchip/rockchip_lvds.c >> @@ -548,7 +548,7 @@ static int rockchip_lvds_bind(struct device *dev, struct device *master, >> struct drm_encoder *encoder; >> struct drm_connector *connector; >> struct device_node *remote = NULL; >> - struct device_node *port, *endpoint; > > Odd extra space before *port in original. Clean that up whilst here. > > >> + struct device_node *port; > > Use __free(device_node) for *port as well. Yes，that is right. > > So where the current asignment is. > struct device_node *port = of_graph_get_port_by_id(dev->of_node, 1); > >> int ret = 0, child_count = 0; >> const char *name; >> u32 endpoint_id = 0; >> @@ -560,15 +560,13 @@ static int rockchip_lvds_bind(struct device *dev, struct device *master, >> "can't found port point, please init lvds panel port!\n"); >> return -EINVAL; >> } >> - for_each_child_of_node(port, endpoint) { >> + for_each_child_of_node_scoped(port, endpoint) { >> child_count++; >> of_property_read_u32(endpoint, "reg", &endpoint_id); >> ret = drm_of_find_panel_or_bridge(dev->of_node, 1, endpoint_id, >> &lvds->panel, &lvds->bridge); >> - if (!ret) { >> - of_node_put(endpoint); >> + if (!ret) >> break; > > This then can simply be > return dev_err_probe(dev, ret, > "failed to find pannel and bridge node\n"); >> - } It seems to me there's no easy way return here, as it will try drm_of_find_panel_or_bridge() for each child node, only "child_count = 0" or all child node drm_of_find_panel_or_bridge() fails it will error and return. > > Various other paths become direct returns as well. > >> } > > The later code with remote looks suspect as not obvious who got the reference that > is being put but assuming that is correct, it's another possible place for __free based > cleanup. Yes, the remote looks suspect. > > >> if (!child_count) { >> DRM_DEV_ERROR(dev, "lvds port does not have any children\n"); >