linux-kernel - [PATCH 20/23] gpio: mockup: add a lock for dummy device list

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Date:   Fri,  4 Sep 2020 17:45:44 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Jonathan Corbet <corbet@....net>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Kent Gibson <warthog618@...il.com>
Cc:     linux-gpio@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: [PATCH 20/23] gpio: mockup: add a lock for dummy device list

From: Bartosz Golaszewski <bgolaszewski@...libre.com>

We'll soon add the possibility to create chips dynamically over debugfs
attributes. Since multiple threads will be able to create devices at
once: add a mutex to protect the device list.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
---
 drivers/gpio/gpio-mockup.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index bc4609e047ef..1353239dc315 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -517,6 +517,7 @@ struct gpio_mockup_device {
 };
 
 static LIST_HEAD(gpio_mockup_devices);
+static DEFINE_MUTEX(gpio_mockup_devices_lock);
 
 static void gpio_mockup_unregister_one_device(struct gpio_mockup_device *dev)
 {
@@ -534,10 +535,14 @@ static void gpio_mockup_unregister_devices(void)
 	struct gpio_mockup_device *mockup_dev;
 	struct list_head *curr, *next;
 
+	mutex_lock(&gpio_mockup_devices_lock);
+
 	list_for_each_safe(curr, next, &gpio_mockup_devices) {
 		mockup_dev = list_entry(curr, struct gpio_mockup_device, list);
 		gpio_mockup_unregister_one_device(mockup_dev);
 	}
+
+	mutex_unlock(&gpio_mockup_devices_lock);
 }
 
 static __init char **gpio_mockup_make_line_names(const char *label,
@@ -588,7 +593,9 @@ static int __init gpio_mockup_register_device(struct property_entry *properties)
 		return PTR_ERR(mockup_dev->pdev);
 	}
 
+	mutex_lock(&gpio_mockup_devices_lock);
 	list_add(&mockup_dev->list, &gpio_mockup_devices);
+	mutex_unlock(&gpio_mockup_devices_lock);
 
 	return 0;
 }
-- 
2.26.1