As timbgpio_irq_enable()/timbgpio_irq_disable() callback could be
executed under irq context, it could introduce double locks on
&tgpio->lock if it preempts other execution units requiring
the same locks.
timbgpio_gpio_set()
--> timbgpio_update_bit()
--> spin_lock(&tgpio->lock)
<interrupt>
--> timbgpio_irq_disable()
--> spin_lock_irqsave(&tgpio->lock)
This flaw was found by an experimental static analysis tool I am
developing for irq-related deadlock.
To prevent the potential deadlock, the patch uses spin_lock_irqsave()
on &tgpio->lock inside timbgpio_gpio_set() to prevent the possible
deadlock scenario.
Signed-off-by: Chengfeng Ye <dg573847474@gmail.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
unsigned offset, bool enabled)
{
struct timbgpio *tgpio = gpiochip_get_data(gpio);
+ unsigned long flags;
u32 reg;
- spin_lock(&tgpio->lock);
+ spin_lock_irqsave(&tgpio->lock, flags);
reg = ioread32(tgpio->membase + offset);
if (enabled)
reg &= ~(1 << index);
iowrite32(reg, tgpio->membase + offset);
- spin_unlock(&tgpio->lock);
+ spin_unlock_irqrestore(&tgpio->lock, flags);
return 0;
}