[PATCH v5 2/7] gpio: mockup: add locking

Bartosz Golaszewski
2019-02-18T16:41:52Z

While no user reported any race condition problems with gpio-mockup,
let's be on the safe side and use a mutex when performing any changes
on the dummy chip structures.

Suggested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
drivers/gpio/gpio-mockup.c | 50 ++++++++++++++++++++++++++++++++------
1 file changed, 43 insertions(+), 7 deletions(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index 6a50f9f59c90..b4c1de6acf74 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -54,6 +54,7 @@ struct gpio_mockup_chip {
struct gpio_mockup_line_status *lines;
struct irq_sim irqsim;
struct dentry *dbg_dir;
+ struct mutex lock;
};

struct gpio_mockup_dbgfs_private {
@@ -82,29 +83,53 @@ static int gpio_mockup_range_ngpio(unsigned int index)
return gpio_mockup_ranges[index * 2 + 1];
}

-static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
+static int __gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);

return chip->lines[offset].value;
}

-static void gpio_mockup_set(struct gpio_chip *gc,
- unsigned int offset, int value)
+static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
+{
+ struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
+ int val;
+
+ mutex_lock(&chip->lock);
+ val = __gpio_mockup_get(gc, offset);
+ mutex_unlock(&chip->lock);
+
+ return val;
+}
+
+static void __gpio_mockup_set(struct gpio_chip *gc,
+ unsigned int offset, int value)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);

chip->lines[offset].value = !!value;
}

+static void gpio_mockup_set(struct gpio_chip *gc,
+ unsigned int offset, int value)
+{
+ struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
+
+ mutex_lock(&chip->lock);
+ __gpio_mockup_set(gc, offset, value);
+ mutex_unlock(&chip->lock);
+}
+
static void gpio_mockup_set_multiple(struct gpio_chip *gc,
unsigned long *mask, unsigned long *bits)
{
+ struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
unsigned int bit;

+ mutex_lock(&chip->lock);
for_each_set_bit(bit, mask, gc->ngpio)
- gpio_mockup_set(gc, bit, test_bit(bit, bits));
-
+ __gpio_mockup_set(gc, bit, test_bit(bit, bits));
+ mutex_unlock(&chip->lock);
}

static int gpio_mockup_dirout(struct gpio_chip *gc,
@@ -112,8 +137,10 @@ static int gpio_mockup_dirout(struct gpio_chip *gc,
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);

- gpio_mockup_set(gc, offset, value);
+ mutex_lock(&chip->lock);
chip->lines[offset].dir = GPIO_MOCKUP_DIR_OUT;
+ __gpio_mockup_set(gc, offset, value);
+ mutex_unlock(&chip->lock);

return 0;
}
@@ -122,7 +149,9 @@ static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);

+ mutex_lock(&chip->lock);
chip->lines[offset].dir = GPIO_MOCKUP_DIR_IN;
+ mutex_unlock(&chip->lock);

return 0;
}
@@ -130,8 +159,13 @@ static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
+ int direction;

- return !chip->lines[offset].dir;
+ mutex_lock(&chip->lock);
+ direction = !chip->lines[offset].dir;
+ mutex_unlock(&chip->lock);
+
+ return direction;
}

static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
@@ -283,6 +317,8 @@ static int gpio_mockup_probe(struct platform_device *pdev)
return -ENOMEM;
}

+ mutex_init(&chip->lock);
+
gc = &chip->gc;
gc->base = base;
gc->ngpio = ngpio;
--
2.20.1