[PATCH v1 1/1] gpio: merrifield: Protect irq_ack() and gpio_set() by lock

[PATCH v1 1/1] gpio: merrifield: Protect irq_ack() and gpio_set() by lock

[Andy Shevchenko]

There is a potential race when two threads do the writes to the same register
in parallel.

Prevent out of order in such case by protecting I/O access by spin lock.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/gpio/gpio-merrifield.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/gpio/gpio-merrifield.c b/drivers/gpio/gpio-merrifield.c
index 11066f6..45b5127 100644
--- a/drivers/gpio/gpio-merrifield.c
+++ b/drivers/gpio/gpio-merrifield.c
@@ -105,7 +105,11 @@ static int mrfld_gpio_get(struct gpio_chip *chip, unsigned int offset)
 static void mrfld_gpio_set(struct gpio_chip *chip, unsigned int offset,
 			   int value)
 {
+	struct mrfld_gpio *priv = gpiochip_get_data(chip);
 	void __iomem *gpsr, *gpcr;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&priv->lock, flags);
 
 	if (value) {
 		gpsr = gpio_reg(chip, offset, GPSR);
@@ -114,6 +118,8 @@ static void mrfld_gpio_set(struct gpio_chip *chip, unsigned int offset,
 		gpcr = gpio_reg(chip, offset, GPCR);
 		writel(BIT(offset % 32), gpcr);
 	}
+
+	raw_spin_unlock_irqrestore(&priv->lock, flags);
 }
 
 static int mrfld_gpio_direction_input(struct gpio_chip *chip,
@@ -160,8 +166,13 @@ static void mrfld_irq_ack(struct irq_data *d)
 	struct mrfld_gpio *priv = irq_data_get_irq_chip_data(d);
 	u32 gpio = irqd_to_hwirq(d);
 	void __iomem *gisr = gpio_reg(&priv->chip, gpio, GISR);
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&priv->lock, flags);
 
 	writel(BIT(gpio % 32), gisr);
+
+	raw_spin_unlock_irqrestore(&priv->lock, flags);
 }
 
 static void mrfld_irq_unmask_mask(struct irq_data *d, bool unmask)
-- 
2.8.1

Re: [PATCH v1 1/1] gpio: merrifield: Protect irq_ack() and gpio_set() by lock

[Linus Walleij]

On Mon, Jul 11, 2016 at 12:06 PM, Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:

> There is a potential race when two threads do the writes to the same register
> in parallel.
>
> Prevent out of order in such case by protecting I/O access by spin lock.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Patch applied.

May I convince you to send a patch adding yourself as maintainer
for this driver in the MAINTAINERS file?

Yours,
Linus Walleij

Re: [PATCH v1 1/1] gpio: merrifield: Protect irq_ack() and gpio_set() by lock

[Andy Shevchenko]

On Mon, 2016-07-11 at 14:22 +0200, Linus Walleij wrote:
> On Mon, Jul 11, 2016 at 12:06 PM, Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> wrote:
> 
> > There is a potential race when two threads do the writes to the same
> > register
> > in parallel.
> > 
> > Prevent out of order in such case by protecting I/O access by spin
> > lock.
> > 
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> 
> Patch applied.
> 
> May I convince you to send a patch adding yourself as maintainer
> for this driver in the MAINTAINERS file?

NP.
And pinctrl perhaps?

-- 

Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy