From patchwork Fri Dec 8 10:20:19 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bartosz Golaszewski X-Patchwork-Id: 752787 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bgdev-pl.20230601.gappssmtp.com header.i=@bgdev-pl.20230601.gappssmtp.com header.b="EP/4/5Pz" Received: from mail-wr1-x42e.google.com (mail-wr1-x42e.google.com [IPv6:2a00:1450:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 43D591708 for ; Fri, 8 Dec 2023 02:20:28 -0800 (PST) Received: by mail-wr1-x42e.google.com with SMTP id ffacd0b85a97d-33330a5617fso1995612f8f.2 for ; Fri, 08 Dec 2023 02:20:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20230601.gappssmtp.com; s=20230601; t=1702030826; x=1702635626; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=xcBt1H06VnpfQ+udlk19+9Kb0QwElKrjTxgmIfyINVE=; b=EP/4/5PzeliOihBSme+38ywRnGlLD66AtuLseXgTuycU+ECUhwT+OU7b+wfjw6JAEd XJvfgXcFymhoMF377pSpRmjGSZLPDPBwqBZ8K40Hx+EB8vH1ZGN579M03/yLtiXqJ2q7 1vs+86Z0TEDigQOYzWUXxl02ZN7nHxcU1fzzmfVv5+EniOLFMt7t93bdTzDOpHZV7ZK6 HN0y9dNxR2oHi+oDcxShw/k4c4EdDJ2ZxJADcwdHtg/+1z84KbqMsif+MQOlJV4ta4Xe pR1m7HEDJmxu4i3O7h308iqL9Vrp2yrJYj72MoeLZ0AHq0PlugDwrCJlEtJmEh5S7P5t jyTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702030826; x=1702635626; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=xcBt1H06VnpfQ+udlk19+9Kb0QwElKrjTxgmIfyINVE=; b=WA3LyhOxDdb26BWK1KPEGOQ6yr/u9jzgWAF9jGwmJRVWjH7feOBPZzIMTVo21J5oGj XVxpgi7unQ0B+TfHEPRt5avkWOodsB8uKRLeHXk9aTYQAvcLl9WXdS5O5m5WSo+fsbY/ 8zh9Q5HtUZ2pGOKdHkcgwg4Lm6Z5282VPUpxrGRn5iVySYks8uKtLEYv1sgmPbAHOLnF ic5Q0nRk9Rz/mjAf5DriCE2U5CXTyndmvdrncPZNufRFUsi9JEL9I5nA5IXBGs4mi9UF CZfARq1aH18rD7H9EMLMCuKJ1dsw2HbMpn5DWPFojeKok0QkM2acxjHRXVJbSDez3Fq4 d+9A== X-Gm-Message-State: AOJu0YwIL70tzHD3GRMBJb/SCvzSsM5BWIvMADFQAbl3Hp6+pemejWa/ 1E26ohcbq9jk0bjDdKNefJMZBg== X-Google-Smtp-Source: AGHT+IEpU9lE4FCaeTWGdOHg5eeTKFEHWPUdBguqaSRXsB3xDodFBETQgvOVjS81LezAfe+3OSSyow== X-Received: by 2002:adf:ed06:0:b0:333:380f:2d2d with SMTP id a6-20020adfed06000000b00333380f2d2dmr2777351wro.92.1702030826702; Fri, 08 Dec 2023 02:20:26 -0800 (PST) Received: from brgl-uxlite.home ([2a01:cb1d:334:ac00:b162:2510:4488:c0c3]) by smtp.gmail.com with ESMTPSA id n16-20020a5d4850000000b003334926fb81sm1678026wrs.90.2023.12.08.02.20.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Dec 2023 02:20:24 -0800 (PST) From: Bartosz Golaszewski To: Linus Walleij , Andy Shevchenko , Kent Gibson Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski Subject: [PATCH v2 1/2] gpiolib: rename static functions that are called with the lock taken Date: Fri, 8 Dec 2023 11:20:19 +0100 Message-Id: <20231208102020.36390-2-brgl@bgdev.pl> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20231208102020.36390-1-brgl@bgdev.pl> References: <20231208102020.36390-1-brgl@bgdev.pl> Precedence: bulk X-Mailing-List: linux-gpio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Bartosz Golaszewski Rename two functions that read or modify the global GPIO device list but don't take the lock themselves (and need to be called with it already acquired). Use the _unlocked() suffix which seems to be used quite consistently across the kernel despite there also existing the _locked() suffix for the same purpose. Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpiolib.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 4e190be75dc2..779f8b21bf05 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -290,7 +290,7 @@ struct gpio_chip *gpio_device_get_chip(struct gpio_device *gdev) EXPORT_SYMBOL_GPL(gpio_device_get_chip); /* dynamic allocation of GPIOs, e.g. on a hotplugged device */ -static int gpiochip_find_base(int ngpio) +static int gpiochip_find_base_unlocked(int ngpio) { struct gpio_device *gdev; int base = GPIO_DYNAMIC_BASE; @@ -363,7 +363,7 @@ EXPORT_SYMBOL_GPL(gpiod_get_direction); * Return -EBUSY if the new chip overlaps with some other chip's integer * space. */ -static int gpiodev_add_to_list(struct gpio_device *gdev) +static int gpiodev_add_to_list_unlocked(struct gpio_device *gdev) { struct gpio_device *prev, *next; @@ -907,7 +907,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, */ base = gc->base; if (base < 0) { - base = gpiochip_find_base(gc->ngpio); + base = gpiochip_find_base_unlocked(gc->ngpio); if (base < 0) { spin_unlock_irqrestore(&gpio_lock, flags); ret = base; @@ -927,7 +927,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, } gdev->base = base; - ret = gpiodev_add_to_list(gdev); + ret = gpiodev_add_to_list_unlocked(gdev); if (ret) { spin_unlock_irqrestore(&gpio_lock, flags); chip_err(gc, "GPIO integer space overlap, cannot add chip\n"); From patchwork Fri Dec 8 10:20:20 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bartosz Golaszewski X-Patchwork-Id: 751851 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bgdev-pl.20230601.gappssmtp.com header.i=@bgdev-pl.20230601.gappssmtp.com header.b="SIq0iawX" Received: from mail-lj1-x22a.google.com (mail-lj1-x22a.google.com [IPv6:2a00:1450:4864:20::22a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 64890121 for ; 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Fri, 08 Dec 2023 02:20:27 -0800 (PST) From: Bartosz Golaszewski To: Linus Walleij , Andy Shevchenko , Kent Gibson Cc: linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski Subject: [PATCH v2 2/2] gpiolib: use a mutex to protect the list of GPIO devices Date: Fri, 8 Dec 2023 11:20:20 +0100 Message-Id: <20231208102020.36390-3-brgl@bgdev.pl> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20231208102020.36390-1-brgl@bgdev.pl> References: <20231208102020.36390-1-brgl@bgdev.pl> Precedence: bulk X-Mailing-List: linux-gpio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Bartosz Golaszewski The global list of GPIO devices is never modified or accessed from atomic context so it's fine to protect it using a mutex. Add a new global lock dedicated to the gpio_devices list and use it whenever accessing or modifying it. While at it: fold the sysfs registering of existing devices into gpiolib.c and make gpio_devices static within its compilation unit. Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpiolib-sysfs.c | 26 +----- drivers/gpio/gpiolib-sysfs.h | 6 ++ drivers/gpio/gpiolib.c | 162 ++++++++++++++++++----------------- drivers/gpio/gpiolib.h | 1 - 4 files changed, 92 insertions(+), 103 deletions(-) diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c index 6f309a3b2d9a..c538568604e8 100644 --- a/drivers/gpio/gpiolib-sysfs.c +++ b/drivers/gpio/gpiolib-sysfs.c @@ -790,9 +790,7 @@ void gpiochip_sysfs_unregister(struct gpio_device *gdev) static int __init gpiolib_sysfs_init(void) { - int status; - unsigned long flags; - struct gpio_device *gdev; + int status; status = class_register(&gpio_class); if (status < 0) @@ -804,26 +802,6 @@ static int __init gpiolib_sysfs_init(void) * We run before arch_initcall() so chip->dev nodes can have * registered, and so arch_initcall() can always gpiod_export(). */ - spin_lock_irqsave(&gpio_lock, flags); - list_for_each_entry(gdev, &gpio_devices, list) { - if (gdev->mockdev) - continue; - - /* - * TODO we yield gpio_lock here because - * gpiochip_sysfs_register() acquires a mutex. This is unsafe - * and needs to be fixed. - * - * Also it would be nice to use gpio_device_find() here so we - * can keep gpio_chips local to gpiolib.c, but the yield of - * gpio_lock prevents us from doing this. - */ - spin_unlock_irqrestore(&gpio_lock, flags); - status = gpiochip_sysfs_register(gdev); - spin_lock_irqsave(&gpio_lock, flags); - } - spin_unlock_irqrestore(&gpio_lock, flags); - - return status; + return gpiochip_sysfs_register_all(); } postcore_initcall(gpiolib_sysfs_init); diff --git a/drivers/gpio/gpiolib-sysfs.h b/drivers/gpio/gpiolib-sysfs.h index b794b396d6a5..ab157cec0b4b 100644 --- a/drivers/gpio/gpiolib-sysfs.h +++ b/drivers/gpio/gpiolib-sysfs.h @@ -8,6 +8,7 @@ struct gpio_device; #ifdef CONFIG_GPIO_SYSFS int gpiochip_sysfs_register(struct gpio_device *gdev); +int gpiochip_sysfs_register_all(void); void gpiochip_sysfs_unregister(struct gpio_device *gdev); #else @@ -17,6 +18,11 @@ static inline int gpiochip_sysfs_register(struct gpio_device *gdev) return 0; } +static inline int gpiochip_sysfs_register_all(void) +{ + return 0; +} + static inline void gpiochip_sysfs_unregister(struct gpio_device *gdev) { } diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 779f8b21bf05..9aaf1d11fdd9 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -2,6 +2,7 @@ #include #include +#include #include #include #include @@ -15,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -94,7 +96,9 @@ DEFINE_SPINLOCK(gpio_lock); static DEFINE_MUTEX(gpio_lookup_lock); static LIST_HEAD(gpio_lookup_list); -LIST_HEAD(gpio_devices); + +static LIST_HEAD(gpio_devices); +static DEFINE_MUTEX(gpio_devices_lock); static DEFINE_MUTEX(gpio_machine_hogs_mutex); static LIST_HEAD(gpio_machine_hogs); @@ -126,20 +130,15 @@ static inline void desc_set_label(struct gpio_desc *d, const char *label) struct gpio_desc *gpio_to_desc(unsigned gpio) { struct gpio_device *gdev; - unsigned long flags; - spin_lock_irqsave(&gpio_lock, flags); - - list_for_each_entry(gdev, &gpio_devices, list) { - if (gdev->base <= gpio && - gdev->base + gdev->ngpio > gpio) { - spin_unlock_irqrestore(&gpio_lock, flags); - return &gdev->descs[gpio - gdev->base]; + scoped_guard(mutex, &gpio_devices_lock) { + list_for_each_entry(gdev, &gpio_devices, list) { + if (gdev->base <= gpio && + gdev->base + gdev->ngpio > gpio) + return &gdev->descs[gpio - gdev->base]; } } - spin_unlock_irqrestore(&gpio_lock, flags); - if (!gpio_is_valid(gpio)) pr_warn("invalid GPIO %d\n", gpio); @@ -412,26 +411,21 @@ static int gpiodev_add_to_list_unlocked(struct gpio_device *gdev) static struct gpio_desc *gpio_name_to_desc(const char * const name) { struct gpio_device *gdev; - unsigned long flags; if (!name) return NULL; - spin_lock_irqsave(&gpio_lock, flags); + guard(mutex)(&gpio_devices_lock); list_for_each_entry(gdev, &gpio_devices, list) { struct gpio_desc *desc; for_each_gpio_desc(gdev->chip, desc) { - if (desc->name && !strcmp(desc->name, name)) { - spin_unlock_irqrestore(&gpio_lock, flags); + if (desc->name && !strcmp(desc->name, name)) return desc; - } } } - spin_unlock_irqrestore(&gpio_lock, flags); - return NULL; } @@ -669,11 +663,9 @@ EXPORT_SYMBOL_GPL(gpiochip_line_is_valid); static void gpiodev_release(struct device *dev) { struct gpio_device *gdev = to_gpio_device(dev); - unsigned long flags; - spin_lock_irqsave(&gpio_lock, flags); - list_del(&gdev->list); - spin_unlock_irqrestore(&gpio_lock, flags); + scoped_guard(mutex, &gpio_devices_lock) + list_del(&gdev->list); ida_free(&gpio_ida, gdev->id); kfree_const(gdev->label); @@ -726,6 +718,27 @@ static int gpiochip_setup_dev(struct gpio_device *gdev) return ret; } +#if IS_ENABLED(CONFIG_GPIO_SYSFS) +int gpiochip_sysfs_register_all(void) +{ + struct gpio_device *gdev; + int ret; + + guard(mutex)(&gpio_devices_lock); + + list_for_each_entry(gdev, &gpio_devices, list) { + if (gdev->mockdev) + continue; + + ret = gpiochip_sysfs_register(gdev); + if (ret) + return ret; + } + + return 0; +} +#endif /* CONFIG_GPIO_SYSFS */ + static void gpiochip_machine_hog(struct gpio_chip *gc, struct gpiod_hog *hog) { struct gpio_desc *desc; @@ -831,7 +844,6 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, struct lock_class_key *request_key) { struct gpio_device *gdev; - unsigned long flags; unsigned int i; int base = 0; int ret = 0; @@ -896,48 +908,45 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, gdev->ngpio = gc->ngpio; - spin_lock_irqsave(&gpio_lock, flags); + scoped_guard(mutex, &gpio_devices_lock) { + /* + * TODO: this allocates a Linux GPIO number base in the global + * GPIO numberspace for this chip. In the long run we want to + * get *rid* of this numberspace and use only descriptors, but + * it may be a pipe dream. It will not happen before we get rid + * of the sysfs interface anyways. + */ + base = gc->base; - /* - * TODO: this allocates a Linux GPIO number base in the global - * GPIO numberspace for this chip. In the long run we want to - * get *rid* of this numberspace and use only descriptors, but - * it may be a pipe dream. It will not happen before we get rid - * of the sysfs interface anyways. - */ - base = gc->base; - if (base < 0) { - base = gpiochip_find_base_unlocked(gc->ngpio); if (base < 0) { - spin_unlock_irqrestore(&gpio_lock, flags); - ret = base; - base = 0; + base = gpiochip_find_base_unlocked(gc->ngpio); + if (base < 0) { + ret = base; + base = 0; + goto err_free_label; + } + /* + * TODO: it should not be necessary to reflect the assigned + * base outside of the GPIO subsystem. Go over drivers and + * see if anyone makes use of this, else drop this and assign + * a poison instead. + */ + gc->base = base; + } else { + dev_warn(&gdev->dev, + "Static allocation of GPIO base is deprecated, use dynamic allocation.\n"); + } + gdev->base = base; + + ret = gpiodev_add_to_list_unlocked(gdev); + if (ret) { + chip_err(gc, "GPIO integer space overlap, cannot add chip\n"); goto err_free_label; } - /* - * TODO: it should not be necessary to reflect the assigned - * base outside of the GPIO subsystem. Go over drivers and - * see if anyone makes use of this, else drop this and assign - * a poison instead. - */ - gc->base = base; - } else { - dev_warn(&gdev->dev, - "Static allocation of GPIO base is deprecated, use dynamic allocation.\n"); + + for (i = 0; i < gc->ngpio; i++) + gdev->descs[i].gdev = gdev; } - gdev->base = base; - - ret = gpiodev_add_to_list_unlocked(gdev); - if (ret) { - spin_unlock_irqrestore(&gpio_lock, flags); - chip_err(gc, "GPIO integer space overlap, cannot add chip\n"); - goto err_free_label; - } - - for (i = 0; i < gc->ngpio; i++) - gdev->descs[i].gdev = gdev; - - spin_unlock_irqrestore(&gpio_lock, flags); BLOCKING_INIT_NOTIFIER_HEAD(&gdev->line_state_notifier); BLOCKING_INIT_NOTIFIER_HEAD(&gdev->device_notifier); @@ -1029,9 +1038,8 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, goto err_print_message; } err_remove_from_list: - spin_lock_irqsave(&gpio_lock, flags); - list_del(&gdev->list); - spin_unlock_irqrestore(&gpio_lock, flags); + scoped_guard(mutex, &gpio_devices_lock) + list_del(&gdev->list); err_free_label: kfree_const(gdev->label); err_free_descs: @@ -1140,7 +1148,7 @@ struct gpio_device *gpio_device_find(void *data, */ might_sleep(); - guard(spinlock_irqsave)(&gpio_lock); + guard(mutex)(&gpio_devices_lock); list_for_each_entry(gdev, &gpio_devices, list) { if (gdev->chip && match(gdev->chip, data)) @@ -4748,35 +4756,33 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_device *gdev) static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos) { - unsigned long flags; struct gpio_device *gdev = NULL; loff_t index = *pos; s->private = ""; - spin_lock_irqsave(&gpio_lock, flags); - list_for_each_entry(gdev, &gpio_devices, list) - if (index-- == 0) { - spin_unlock_irqrestore(&gpio_lock, flags); + guard(mutex)(&gpio_devices_lock); + + list_for_each_entry(gdev, &gpio_devices, list) { + if (index-- == 0) return gdev; - } - spin_unlock_irqrestore(&gpio_lock, flags); + } return NULL; } static void *gpiolib_seq_next(struct seq_file *s, void *v, loff_t *pos) { - unsigned long flags; struct gpio_device *gdev = v; void *ret = NULL; - spin_lock_irqsave(&gpio_lock, flags); - if (list_is_last(&gdev->list, &gpio_devices)) - ret = NULL; - else - ret = list_first_entry(&gdev->list, struct gpio_device, list); - spin_unlock_irqrestore(&gpio_lock, flags); + scoped_guard(mutex, &gpio_devices_lock) { + if (list_is_last(&gdev->list, &gpio_devices)) + ret = NULL; + else + ret = list_first_entry(&gdev->list, struct gpio_device, + list); + } s->private = "\n"; ++*pos; diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h index 3ccacf3c1288..9278796db079 100644 --- a/drivers/gpio/gpiolib.h +++ b/drivers/gpio/gpiolib.h @@ -135,7 +135,6 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep, int gpiod_set_transitory(struct gpio_desc *desc, bool transitory); extern spinlock_t gpio_lock; -extern struct list_head gpio_devices; void gpiod_line_state_notify(struct gpio_desc *desc, unsigned long action);