From patchwork Thu Nov 12 16:36:19 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Nicolas Saenz Julienne X-Patchwork-Id: 1399093 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-pwm-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=suse.de Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4CX6mc2NYDz9sSf for ; Fri, 13 Nov 2020 03:41:04 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728906AbgKLQlA (ORCPT ); Thu, 12 Nov 2020 11:41:00 -0500 Received: from mx2.suse.de ([195.135.220.15]:44752 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728263AbgKLQlA (ORCPT ); Thu, 12 Nov 2020 11:41:00 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id B4473AB95; Thu, 12 Nov 2020 16:40:57 +0000 (UTC) From: Nicolas Saenz Julienne To: u.kleine-koenig@pengutronix.de, linux-kernel@vger.kernel.org, Florian Fainelli , Ray Jui , Scott Branden , bcm-kernel-feedback-list@broadcom.com, Nicolas Saenz Julienne Cc: linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, wahrenst@gmx.net, linux-input@vger.kernel.org, dmitry.torokhov@gmail.com, gregkh@linuxfoundation.org, devel@driverdev.osuosl.org, p.zabel@pengutronix.de, linux-gpio@vger.kernel.org, linus.walleij@linaro.org, linux-clk@vger.kernel.org, sboyd@kernel.org, linux-rpi-kernel@lists.infradead.org, bgolaszewski@baylibre.com, andy.shevchenko@gmail.com Subject: [PATCH v4 01/11] firmware: raspberrypi: Keep count of all consumers Date: Thu, 12 Nov 2020 17:36:19 +0100 Message-Id: <20201112163630.17177-2-nsaenzjulienne@suse.de> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201112163630.17177-1-nsaenzjulienne@suse.de> References: <20201112163630.17177-1-nsaenzjulienne@suse.de> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pwm@vger.kernel.org When unbinding the firmware device we need to make sure it has no consumers left. Otherwise we'd leave them with a firmware handle pointing at freed memory. Keep a reference count of all consumers and introduce rpi_firmware_put() which will permit automatically decrease the reference count upon unbinding consumer drivers. Suggested-by: Uwe Kleine-König Signed-off-by: Nicolas Saenz Julienne --- Changes since v3: - Use kref instead of waiting on refcount drivers/firmware/raspberrypi.c | 37 +++++++++++++++++++--- include/soc/bcm2835/raspberrypi-firmware.h | 2 ++ 2 files changed, 35 insertions(+), 4 deletions(-) diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c index 2371d08bdd17..438e17074a97 100644 --- a/drivers/firmware/raspberrypi.c +++ b/drivers/firmware/raspberrypi.c @@ -7,6 +7,7 @@ */ #include +#include #include #include #include @@ -27,6 +28,8 @@ struct rpi_firmware { struct mbox_chan *chan; /* The property channel. */ struct completion c; u32 enabled; + + struct kref consumers; }; static DEFINE_MUTEX(transaction_lock); @@ -225,12 +228,27 @@ static void rpi_register_clk_driver(struct device *dev) -1, NULL, 0); } +static void rpi_firmware_delete(struct kref *kref) +{ + struct rpi_firmware *fw = container_of(kref, struct rpi_firmware, + consumers); + + mbox_free_channel(fw->chan); + kfree(fw); +} + +void rpi_firmware_put(struct rpi_firmware *fw) +{ + kref_put(&fw->consumers, rpi_firmware_delete); +} +EXPORT_SYMBOL_GPL(rpi_firmware_put); + static int rpi_firmware_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; struct rpi_firmware *fw; - fw = devm_kzalloc(dev, sizeof(*fw), GFP_KERNEL); + fw = kzalloc(sizeof(*fw), GFP_KERNEL); if (!fw) return -ENOMEM; @@ -247,6 +265,7 @@ static int rpi_firmware_probe(struct platform_device *pdev) } init_completion(&fw->c); + kref_init(&fw->consumers); platform_set_drvdata(pdev, fw); @@ -275,25 +294,35 @@ static int rpi_firmware_remove(struct platform_device *pdev) rpi_hwmon = NULL; platform_device_unregister(rpi_clk); rpi_clk = NULL; - mbox_free_channel(fw->chan); + + rpi_firmware_put(fw); return 0; } /** - * rpi_firmware_get - Get pointer to rpi_firmware structure. * @firmware_node: Pointer to the firmware Device Tree node. * + * The reference to rpi_firmware has to be released with rpi_firmware_put(). + * * Returns NULL is the firmware device is not ready. */ struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node) { struct platform_device *pdev = of_find_device_by_node(firmware_node); + struct rpi_firmware *fw; if (!pdev) return NULL; - return platform_get_drvdata(pdev); + fw = platform_get_drvdata(pdev); + if (!fw) + return NULL; + + if (!kref_get_unless_zero(&fw->consumers)) + return NULL; + + return fw; } EXPORT_SYMBOL_GPL(rpi_firmware_get); diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h index cc9cdbc66403..fdfef7fe40df 100644 --- a/include/soc/bcm2835/raspberrypi-firmware.h +++ b/include/soc/bcm2835/raspberrypi-firmware.h @@ -140,6 +140,7 @@ int rpi_firmware_property(struct rpi_firmware *fw, u32 tag, void *data, size_t len); int rpi_firmware_property_list(struct rpi_firmware *fw, void *data, size_t tag_size); +void rpi_firmware_put(struct rpi_firmware *fw); struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node); #else static inline int rpi_firmware_property(struct rpi_firmware *fw, u32 tag, @@ -154,6 +155,7 @@ static inline int rpi_firmware_property_list(struct rpi_firmware *fw, return -ENOSYS; } +static inline void rpi_firmware_put(struct rpi_firmware *fw) { } static inline struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node) { return NULL;