Messages in this thread Patch in this message | | | From | Sasha Levin <> | Subject | [PATCH AUTOSEL 5.4 6/8] gpio: timberdale: Fix potential deadlock on &tgpio->lock | Date | Sat, 7 Oct 2023 20:50:22 -0400 |
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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 de14949a3fe5a..92c1f2baa4bff 100644 --- a/drivers/gpio/gpio-timberdale.c +++ b/drivers/gpio/gpio-timberdale.c @@ -43,9 +43,10 @@ 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) @@ -54,7 +55,7 @@ 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; } -- 2.40.1
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