From patchwork Wed Jul 8 12:59:12 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vladimir Zapolskiy X-Patchwork-Id: 6747061 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 234C09F52D for ; Wed, 8 Jul 2015 13:03:41 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 2CB29206D7 for ; Wed, 8 Jul 2015 13:03:39 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7A8B72069E for ; Wed, 8 Jul 2015 13:03:33 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZCoye-0003If-2B; Wed, 08 Jul 2015 13:01:28 +0000 Received: from relay1.mentorg.com ([192.94.38.131]) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZCoy1-0002wj-Ta for linux-arm-kernel@lists.infradead.org; Wed, 08 Jul 2015 13:00:51 +0000 Received: from nat-ies.mentorg.com ([192.94.31.2] helo=SVR-IES-FEM-01.mgc.mentorg.com) by relay1.mentorg.com with esmtp id 1ZCoxj-0004Ak-0J from Vladimir_Zapolskiy@mentor.com ; Wed, 08 Jul 2015 06:00:31 -0700 Received: from eyas.fin.mentorg.com (137.202.0.76) by SVR-IES-FEM-01.mgc.mentorg.com (137.202.0.104) with Microsoft SMTP Server (TLS) id 14.3.224.2; Wed, 8 Jul 2015 13:59:16 +0100 From: Vladimir Zapolskiy To: Wolfram Sang , David Airlie , "Thierry Reding" Subject: [PATCH 01/10] i2c: add and export of_get_i2c_adapter_by_node() interface Date: Wed, 8 Jul 2015 15:59:12 +0300 Message-ID: <1436360352-9181-1-git-send-email-vladimir_zapolskiy@mentor.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1436360095-9065-1-git-send-email-vladimir_zapolskiy@mentor.com> References: <1436360095-9065-1-git-send-email-vladimir_zapolskiy@mentor.com> MIME-Version: 1.0 X-Originating-IP: [137.202.0.76] X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150708_060050_031909_6C41BEF4 X-CRM114-Status: UNSURE ( 9.06 ) X-CRM114-Notice: Please train this message. X-Spam-Score: -2.6 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fabio Estevam , Philipp Zabel , dri-devel@lists.freedesktop.org, Inki Dae , Tomi Valkeinen , linux-i2c@vger.kernel.org, Benjamin Gaignard , Andy Yan , Russell King , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP of_find_i2c_adapter_by_node() call requires quite often missing put_device(), and i2c_put_adapter() releases a device locked by i2c_get_adapter() only. In general module_put(adapter->owner) and put_device(dev) are not interchangeable. This is a common error reproduction scenario as a result of the misusage described above (for clearness this is run on iMX6 platform with HDMI and I2C bus drivers compiled as kernel modules): root@mx6q:~# lsmod | grep i2c i2c_imx 10213 0 root@mx6q:~# lsmod | grep dw_hdmi_imx dw_hdmi_imx 3631 0 dw_hdmi 11846 1 dw_hdmi_imx imxdrm 8674 3 dw_hdmi_imx,imx_ipuv3_crtc,imx_ldb drm_kms_helper 113765 5 dw_hdmi,imxdrm,imx_ipuv3_crtc,imx_ldb root@mx6q:~# rmmod dw_hdmi_imx root@mx6q:~# lsmod | grep i2c i2c_imx 10213 -1 ^^^^^ root@mx6q:~# rmmod i2c_imx rmmod: ERROR: Module i2c_imx is in use To fix existing users of these interfaces and to avoid any further confusion and misusage in future, add one more interface of_get_i2c_adapter_by_node(), it is similar to i2c_get_adapter() in sense that an I2C bus device driver found and locked by user can be correctly unlocked by i2c_put_adapter(). Signed-off-by: Vladimir Zapolskiy --- The change is based on RFC http://www.spinics.net/lists/linux-i2c/msg20257.html * added new exported function declaration in include/linux/i2c.h * added put_device(dev) call right inside of_get_i2c_adapter_by_node() * corrected authorship of the change drivers/i2c/i2c-core.c | 20 ++++++++++++++++++++ include/linux/i2c.h | 6 ++++++ 2 files changed, 26 insertions(+) diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index 069a41f..0d902ab 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -1356,6 +1356,26 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node) return i2c_verify_adapter(dev); } EXPORT_SYMBOL(of_find_i2c_adapter_by_node); + +struct i2c_adapter *of_get_i2c_adapter_by_node(struct device_node *node) +{ + struct device *dev; + struct i2c_adapter *adapter; + + dev = bus_find_device(&i2c_bus_type, NULL, node, + of_dev_node_match); + if (!dev) + return NULL; + + adapter = i2c_verify_adapter(dev); + if (adapter && !try_module_get(adapter->owner)) + adapter = NULL; + + put_device(dev); + + return adapter; +} +EXPORT_SYMBOL(of_get_i2c_adapter_by_node); #else static void of_i2c_register_devices(struct i2c_adapter *adap) { } #endif /* CONFIG_OF */ diff --git a/include/linux/i2c.h b/include/linux/i2c.h index e83a738..87bb217 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -638,6 +638,7 @@ extern struct i2c_client *of_find_i2c_device_by_node(struct device_node *node); /* must call put_device() when done with returned i2c_adapter device */ extern struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node); +struct i2c_adapter *of_get_i2c_adapter_by_node(struct device_node *node); #else static inline struct i2c_client *of_find_i2c_device_by_node(struct device_node *node) @@ -649,6 +650,11 @@ static inline struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node { return NULL; } + +static inline struct i2c_adapter *of_get_i2c_adapter_by_node(struct device_node *node) +{ + return NULL; +} #endif /* CONFIG_OF */ #endif /* _LINUX_I2C_H */