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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 Reviewed-by: Andy Shevchenko Reviewed-by: Linus Walleij --- 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 6efe44570333..5b744d1f31f6 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -290,7 +290,7 @@ struct gpio_chip *gpio_device_get_chip(struct gpio_devi= ce *gdev) EXPORT_SYMBOL_GPL(gpio_device_get_chip); =20 /* 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 =3D 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; =20 @@ -907,7 +907,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, vo= id *data, */ base =3D gc->base; if (base < 0) { - base =3D gpiochip_find_base(gc->ngpio); + base =3D gpiochip_find_base_unlocked(gc->ngpio); if (base < 0) { spin_unlock_irqrestore(&gpio_lock, flags); ret =3D base; @@ -927,7 +927,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, vo= id *data, } gdev->base =3D base; =20 - ret =3D gpiodev_add_to_list(gdev); + ret =3D 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"); --=20 2.40.1 From nobody Tue Dec 16 16:40:35 2025 Received: from mail-wm1-f54.google.com (mail-wm1-f54.google.com [209.85.128.54]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DF5A739FC9 for ; Fri, 15 Dec 2023 15:53:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=bgdev.pl Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bgdev.pl Authentication-Results: smtp.subspace.kernel.org; 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Fri, 15 Dec 2023 07:53:06 -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 v3 2/2] gpiolib: use a mutex to protect the list of GPIO devices Date: Fri, 15 Dec 2023 16:53:00 +0100 Message-Id: <20231215155300.21186-3-brgl@bgdev.pl> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20231215155300.21186-1-brgl@bgdev.pl> References: <20231215155300.21186-1-brgl@bgdev.pl> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 Reviewed-by: Andy Shevchenko Reviewed-by: Linus Walleij --- drivers/gpio/gpiolib-sysfs.c | 45 ++++++------ drivers/gpio/gpiolib-sysfs.h | 6 ++ drivers/gpio/gpiolib.c | 139 ++++++++++++++++------------------- drivers/gpio/gpiolib.h | 2 + 4 files changed, 91 insertions(+), 101 deletions(-) diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c index 6f309a3b2d9a..ae4fc013b675 100644 --- a/drivers/gpio/gpiolib-sysfs.c +++ b/drivers/gpio/gpiolib-sysfs.c @@ -766,6 +766,25 @@ int gpiochip_sysfs_register(struct gpio_device *gdev) return 0; } =20 +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 =3D gpiochip_sysfs_register(gdev); + if (ret) + return ret; + } + + return 0; +} + void gpiochip_sysfs_unregister(struct gpio_device *gdev) { struct gpio_desc *desc; @@ -790,9 +809,7 @@ void gpiochip_sysfs_unregister(struct gpio_device *gdev) =20 static int __init gpiolib_sysfs_init(void) { - int status; - unsigned long flags; - struct gpio_device *gdev; + int status; =20 status =3D class_register(&gpio_class); if (status < 0) @@ -804,26 +821,6 @@ 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 =3D 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 =20 int gpiochip_sysfs_register(struct gpio_device *gdev); +int gpiochip_sysfs_register_all(void); void gpiochip_sysfs_unregister(struct gpio_device *gdev); =20 #else @@ -17,6 +18,11 @@ static inline int gpiochip_sysfs_register(struct gpio_de= vice *gdev) return 0; } =20 +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 5b744d1f31f6..9508396c967e 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -2,6 +2,7 @@ =20 #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); =20 static DEFINE_MUTEX(gpio_lookup_lock); static LIST_HEAD(gpio_lookup_list); + LIST_HEAD(gpio_devices); +DEFINE_MUTEX(gpio_devices_lock); =20 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; =20 - spin_lock_irqsave(&gpio_lock, flags); - - list_for_each_entry(gdev, &gpio_devices, list) { - if (gdev->base <=3D 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 <=3D gpio && + gdev->base + gdev->ngpio > gpio) + return &gdev->descs[gpio - gdev->base]; } } =20 - spin_unlock_irqrestore(&gpio_lock, flags); - if (!gpio_is_valid(gpio)) pr_warn("invalid GPIO %d\n", gpio); =20 @@ -412,26 +411,21 @@ static int gpiodev_add_to_list_unlocked(struct gpio_d= evice *gdev) static struct gpio_desc *gpio_name_to_desc(const char * const name) { struct gpio_device *gdev; - unsigned long flags; =20 if (!name) return NULL; =20 - spin_lock_irqsave(&gpio_lock, flags); + guard(mutex)(&gpio_devices_lock); =20 list_for_each_entry(gdev, &gpio_devices, list) { struct gpio_desc *desc; =20 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; - } } } =20 - spin_unlock_irqrestore(&gpio_lock, flags); - return NULL; } =20 @@ -669,11 +663,9 @@ EXPORT_SYMBOL_GPL(gpiochip_line_is_valid); static void gpiodev_release(struct device *dev) { struct gpio_device *gdev =3D to_gpio_device(dev); - unsigned long flags; =20 - 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); =20 ida_free(&gpio_ida, gdev->id); kfree_const(gdev->label); @@ -831,7 +823,6 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, vo= id *data, struct lock_class_key *request_key) { struct gpio_device *gdev; - unsigned long flags; unsigned int i; int base =3D 0; int ret =3D 0; @@ -896,48 +887,45 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, = void *data, =20 gdev->ngpio =3D gc->ngpio; =20 - 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 =3D gc->base; =20 - /* - * 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 =3D gc->base; - if (base < 0) { - base =3D gpiochip_find_base_unlocked(gc->ngpio); if (base < 0) { - spin_unlock_irqrestore(&gpio_lock, flags); - ret =3D base; - base =3D 0; + base =3D gpiochip_find_base_unlocked(gc->ngpio); + if (base < 0) { + ret =3D base; + base =3D 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 =3D base; + } else { + dev_warn(&gdev->dev, + "Static allocation of GPIO base is deprecated, use dynamic allocation= .\n"); + } + gdev->base =3D base; + + ret =3D 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 =3D base; - } else { - dev_warn(&gdev->dev, - "Static allocation of GPIO base is deprecated, use dynamic allocation.= \n"); + + for (i =3D 0; i < gc->ngpio; i++) + gdev->descs[i].gdev =3D gdev; } - gdev->base =3D base; - - ret =3D 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 =3D 0; i < gc->ngpio; i++) - gdev->descs[i].gdev =3D gdev; - - spin_unlock_irqrestore(&gpio_lock, flags); =20 BLOCKING_INIT_NOTIFIER_HEAD(&gdev->line_state_notifier); BLOCKING_INIT_NOTIFIER_HEAD(&gdev->device_notifier); @@ -1029,9 +1017,8 @@ 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 +1127,7 @@ struct gpio_device *gpio_device_find(void *data, */ might_sleep(); =20 - guard(spinlock_irqsave)(&gpio_lock); + guard(mutex)(&gpio_devices_lock); =20 list_for_each_entry(gdev, &gpio_devices, list) { if (gdev->chip && match(gdev->chip, data)) @@ -4756,35 +4743,33 @@ static void gpiolib_dbg_show(struct seq_file *s, st= ruct gpio_device *gdev) =20 static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos) { - unsigned long flags; struct gpio_device *gdev =3D NULL; loff_t index =3D *pos; =20 s->private =3D ""; =20 - spin_lock_irqsave(&gpio_lock, flags); - list_for_each_entry(gdev, &gpio_devices, list) - if (index-- =3D=3D 0) { - spin_unlock_irqrestore(&gpio_lock, flags); + guard(mutex)(&gpio_devices_lock); + + list_for_each_entry(gdev, &gpio_devices, list) { + if (index-- =3D=3D 0) return gdev; - } - spin_unlock_irqrestore(&gpio_lock, flags); + } =20 return NULL; } =20 static void *gpiolib_seq_next(struct seq_file *s, void *v, loff_t *pos) { - unsigned long flags; struct gpio_device *gdev =3D v; void *ret =3D NULL; =20 - spin_lock_irqsave(&gpio_lock, flags); - if (list_is_last(&gdev->list, &gpio_devices)) - ret =3D NULL; - else - ret =3D 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 =3D NULL; + else + ret =3D list_first_entry(&gdev->list, struct gpio_device, + list); + } =20 s->private =3D "\n"; ++*pos; diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h index 3ccacf3c1288..8142b5cbc395 100644 --- a/drivers/gpio/gpiolib.h +++ b/drivers/gpio/gpiolib.h @@ -15,6 +15,7 @@ #include /* for enum gpiod_flags */ #include #include +#include #include #include =20 @@ -136,6 +137,7 @@ int gpiod_set_transitory(struct gpio_desc *desc, bool t= ransitory); =20 extern spinlock_t gpio_lock; extern struct list_head gpio_devices; +extern struct mutex gpio_devices_lock; =20 void gpiod_line_state_notify(struct gpio_desc *desc, unsigned long action); =20 --=20 2.40.1