4.14-stable review patch. If anyone has any objections, please let me know.
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From: Chengfeng Ye dg573847474@gmail.com
[ Upstream commit 9e8bc2dda5a7a8e2babc9975f4b11c9a6196e490 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpio/gpio-timberdale.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/gpio/gpio-timberdale.c b/drivers/gpio/gpio-timberdale.c index 181f86ce00cd4..639c8daaeb310 100644 --- a/drivers/gpio/gpio-timberdale.c +++ b/drivers/gpio/gpio-timberdale.c @@ -55,9 +55,10 @@ static int timbgpio_update_bit(struct gpio_chip *gpio, unsigned index, 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) @@ -66,7 +67,7 @@ static int timbgpio_update_bit(struct gpio_chip *gpio, unsigned index, reg &= ~(1 << index);
iowrite32(reg, tgpio->membase + offset); - spin_unlock(&tgpio->lock); + spin_unlock_irqrestore(&tgpio->lock, flags);
return 0; }