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https://github.com/torvalds/linux.git
synced 2024-11-24 21:21:41 +00:00
gpiolib: use a mutex to protect the list of GPIO devices
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. Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
This commit is contained in:
Bartosz Golaszewski
parent
f95fd4ac15
commit
65a828bab1
@ -766,6 +766,25 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
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return 0;
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}
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int gpiochip_sysfs_register_all(void)
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{
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struct gpio_device *gdev;
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int ret;
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guard(mutex)(&gpio_devices_lock);
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list_for_each_entry(gdev, &gpio_devices, list) {
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if (gdev->mockdev)
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continue;
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ret = gpiochip_sysfs_register(gdev);
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if (ret)
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return ret;
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}
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return 0;
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}
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void gpiochip_sysfs_unregister(struct gpio_device *gdev)
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{
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struct gpio_desc *desc;
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@ -790,9 +809,7 @@ void gpiochip_sysfs_unregister(struct gpio_device *gdev)
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static int __init gpiolib_sysfs_init(void)
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{
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int status;
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unsigned long flags;
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struct gpio_device *gdev;
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int status;
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status = class_register(&gpio_class);
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if (status < 0)
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@ -804,26 +821,6 @@ static int __init gpiolib_sysfs_init(void)
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* We run before arch_initcall() so chip->dev nodes can have
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* registered, and so arch_initcall() can always gpiod_export().
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*/
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spin_lock_irqsave(&gpio_lock, flags);
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list_for_each_entry(gdev, &gpio_devices, list) {
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if (gdev->mockdev)
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continue;
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/*
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* TODO we yield gpio_lock here because
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* gpiochip_sysfs_register() acquires a mutex. This is unsafe
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* and needs to be fixed.
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*
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* Also it would be nice to use gpio_device_find() here so we
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* can keep gpio_chips local to gpiolib.c, but the yield of
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* gpio_lock prevents us from doing this.
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*/
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spin_unlock_irqrestore(&gpio_lock, flags);
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status = gpiochip_sysfs_register(gdev);
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spin_lock_irqsave(&gpio_lock, flags);
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}
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spin_unlock_irqrestore(&gpio_lock, flags);
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return status;
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return gpiochip_sysfs_register_all();
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}
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postcore_initcall(gpiolib_sysfs_init);
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@ -8,6 +8,7 @@ struct gpio_device;
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#ifdef CONFIG_GPIO_SYSFS
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int gpiochip_sysfs_register(struct gpio_device *gdev);
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int gpiochip_sysfs_register_all(void);
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void gpiochip_sysfs_unregister(struct gpio_device *gdev);
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#else
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@ -17,6 +18,11 @@ static inline int gpiochip_sysfs_register(struct gpio_device *gdev)
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return 0;
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}
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static inline int gpiochip_sysfs_register_all(void)
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{
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return 0;
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}
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static inline void gpiochip_sysfs_unregister(struct gpio_device *gdev)
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{
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}
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@ -2,6 +2,7 @@
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#include <linux/acpi.h>
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#include <linux/bitmap.h>
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#include <linux/cleanup.h>
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#include <linux/compat.h>
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#include <linux/debugfs.h>
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#include <linux/device.h>
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@ -15,6 +16,7 @@
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/of.h>
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#include <linux/pinctrl/consumer.h>
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#include <linux/seq_file.h>
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@ -94,7 +96,9 @@ DEFINE_SPINLOCK(gpio_lock);
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static DEFINE_MUTEX(gpio_lookup_lock);
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static LIST_HEAD(gpio_lookup_list);
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LIST_HEAD(gpio_devices);
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DEFINE_MUTEX(gpio_devices_lock);
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static DEFINE_MUTEX(gpio_machine_hogs_mutex);
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static LIST_HEAD(gpio_machine_hogs);
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@ -126,20 +130,15 @@ static inline void desc_set_label(struct gpio_desc *d, const char *label)
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struct gpio_desc *gpio_to_desc(unsigned gpio)
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{
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struct gpio_device *gdev;
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unsigned long flags;
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spin_lock_irqsave(&gpio_lock, flags);
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list_for_each_entry(gdev, &gpio_devices, list) {
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if (gdev->base <= gpio &&
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gdev->base + gdev->ngpio > gpio) {
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spin_unlock_irqrestore(&gpio_lock, flags);
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return &gdev->descs[gpio - gdev->base];
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scoped_guard(mutex, &gpio_devices_lock) {
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list_for_each_entry(gdev, &gpio_devices, list) {
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if (gdev->base <= gpio &&
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gdev->base + gdev->ngpio > gpio)
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return &gdev->descs[gpio - gdev->base];
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}
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}
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spin_unlock_irqrestore(&gpio_lock, flags);
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if (!gpio_is_valid(gpio))
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pr_warn("invalid GPIO %d\n", gpio);
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@ -412,26 +411,21 @@ static int gpiodev_add_to_list_unlocked(struct gpio_device *gdev)
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static struct gpio_desc *gpio_name_to_desc(const char * const name)
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{
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struct gpio_device *gdev;
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unsigned long flags;
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if (!name)
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return NULL;
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spin_lock_irqsave(&gpio_lock, flags);
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guard(mutex)(&gpio_devices_lock);
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list_for_each_entry(gdev, &gpio_devices, list) {
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struct gpio_desc *desc;
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for_each_gpio_desc(gdev->chip, desc) {
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if (desc->name && !strcmp(desc->name, name)) {
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spin_unlock_irqrestore(&gpio_lock, flags);
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if (desc->name && !strcmp(desc->name, name))
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return desc;
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}
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}
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}
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spin_unlock_irqrestore(&gpio_lock, flags);
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return NULL;
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}
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@ -669,11 +663,9 @@ EXPORT_SYMBOL_GPL(gpiochip_line_is_valid);
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static void gpiodev_release(struct device *dev)
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{
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struct gpio_device *gdev = to_gpio_device(dev);
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unsigned long flags;
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spin_lock_irqsave(&gpio_lock, flags);
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list_del(&gdev->list);
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spin_unlock_irqrestore(&gpio_lock, flags);
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scoped_guard(mutex, &gpio_devices_lock)
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list_del(&gdev->list);
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ida_free(&gpio_ida, gdev->id);
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kfree_const(gdev->label);
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@ -831,7 +823,6 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
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struct lock_class_key *request_key)
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{
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struct gpio_device *gdev;
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unsigned long flags;
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unsigned int i;
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int base = 0;
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int ret = 0;
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@ -896,48 +887,45 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
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gdev->ngpio = gc->ngpio;
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spin_lock_irqsave(&gpio_lock, flags);
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scoped_guard(mutex, &gpio_devices_lock) {
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/*
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* TODO: this allocates a Linux GPIO number base in the global
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* GPIO numberspace for this chip. In the long run we want to
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* get *rid* of this numberspace and use only descriptors, but
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* it may be a pipe dream. It will not happen before we get rid
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* of the sysfs interface anyways.
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*/
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base = gc->base;
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/*
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* TODO: this allocates a Linux GPIO number base in the global
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* GPIO numberspace for this chip. In the long run we want to
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* get *rid* of this numberspace and use only descriptors, but
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* it may be a pipe dream. It will not happen before we get rid
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* of the sysfs interface anyways.
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*/
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base = gc->base;
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if (base < 0) {
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base = gpiochip_find_base_unlocked(gc->ngpio);
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if (base < 0) {
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spin_unlock_irqrestore(&gpio_lock, flags);
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ret = base;
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base = 0;
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base = gpiochip_find_base_unlocked(gc->ngpio);
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if (base < 0) {
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ret = base;
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base = 0;
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goto err_free_label;
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}
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/*
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* TODO: it should not be necessary to reflect the assigned
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* base outside of the GPIO subsystem. Go over drivers and
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* see if anyone makes use of this, else drop this and assign
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* a poison instead.
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*/
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gc->base = base;
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} else {
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dev_warn(&gdev->dev,
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"Static allocation of GPIO base is deprecated, use dynamic allocation.\n");
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}
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gdev->base = base;
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ret = gpiodev_add_to_list_unlocked(gdev);
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if (ret) {
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chip_err(gc, "GPIO integer space overlap, cannot add chip\n");
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goto err_free_label;
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}
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/*
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* TODO: it should not be necessary to reflect the assigned
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* base outside of the GPIO subsystem. Go over drivers and
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* see if anyone makes use of this, else drop this and assign
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* a poison instead.
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*/
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gc->base = base;
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} else {
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dev_warn(&gdev->dev,
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"Static allocation of GPIO base is deprecated, use dynamic allocation.\n");
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for (i = 0; i < gc->ngpio; i++)
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gdev->descs[i].gdev = gdev;
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}
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gdev->base = base;
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ret = gpiodev_add_to_list_unlocked(gdev);
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if (ret) {
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spin_unlock_irqrestore(&gpio_lock, flags);
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chip_err(gc, "GPIO integer space overlap, cannot add chip\n");
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goto err_free_label;
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}
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for (i = 0; i < gc->ngpio; i++)
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gdev->descs[i].gdev = gdev;
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spin_unlock_irqrestore(&gpio_lock, flags);
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BLOCKING_INIT_NOTIFIER_HEAD(&gdev->line_state_notifier);
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BLOCKING_INIT_NOTIFIER_HEAD(&gdev->device_notifier);
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@ -1029,9 +1017,8 @@ err_free_gpiochip_mask:
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goto err_print_message;
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}
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err_remove_from_list:
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spin_lock_irqsave(&gpio_lock, flags);
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list_del(&gdev->list);
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spin_unlock_irqrestore(&gpio_lock, flags);
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scoped_guard(mutex, &gpio_devices_lock)
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list_del(&gdev->list);
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err_free_label:
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kfree_const(gdev->label);
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err_free_descs:
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@ -1140,7 +1127,7 @@ struct gpio_device *gpio_device_find(void *data,
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*/
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might_sleep();
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guard(spinlock_irqsave)(&gpio_lock);
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guard(mutex)(&gpio_devices_lock);
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list_for_each_entry(gdev, &gpio_devices, list) {
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if (gdev->chip && match(gdev->chip, data))
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@ -4756,35 +4743,33 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_device *gdev)
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static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos)
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{
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unsigned long flags;
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struct gpio_device *gdev = NULL;
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loff_t index = *pos;
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s->private = "";
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spin_lock_irqsave(&gpio_lock, flags);
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list_for_each_entry(gdev, &gpio_devices, list)
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if (index-- == 0) {
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spin_unlock_irqrestore(&gpio_lock, flags);
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guard(mutex)(&gpio_devices_lock);
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list_for_each_entry(gdev, &gpio_devices, list) {
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if (index-- == 0)
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return gdev;
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}
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spin_unlock_irqrestore(&gpio_lock, flags);
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}
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return NULL;
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}
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static void *gpiolib_seq_next(struct seq_file *s, void *v, loff_t *pos)
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{
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unsigned long flags;
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struct gpio_device *gdev = v;
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void *ret = NULL;
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spin_lock_irqsave(&gpio_lock, flags);
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if (list_is_last(&gdev->list, &gpio_devices))
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ret = NULL;
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else
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ret = list_first_entry(&gdev->list, struct gpio_device, list);
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spin_unlock_irqrestore(&gpio_lock, flags);
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scoped_guard(mutex, &gpio_devices_lock) {
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if (list_is_last(&gdev->list, &gpio_devices))
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ret = NULL;
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else
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ret = list_first_entry(&gdev->list, struct gpio_device,
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list);
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}
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s->private = "\n";
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++*pos;
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@ -15,6 +15,7 @@
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#include <linux/gpio/consumer.h> /* for enum gpiod_flags */
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#include <linux/gpio/driver.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/notifier.h>
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#include <linux/rwsem.h>
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@ -136,6 +137,7 @@ int gpiod_set_transitory(struct gpio_desc *desc, bool transitory);
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extern spinlock_t gpio_lock;
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extern struct list_head gpio_devices;
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extern struct mutex gpio_devices_lock;
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void gpiod_line_state_notify(struct gpio_desc *desc, unsigned long action);
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