linux-kernel - [PATCH] gpiolib: irq hooks: fix recursion in gpiochip_irq

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Message-Id: <20201210070514.13238-1-nikita.shubin@maquefel.me>
Date:   Thu, 10 Dec 2020 10:05:14 +0300
From:   Nikita Shubin <nikita.shubin@...uefel.me>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Nikita Shubin <nikita.shubin@...uefel.me>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Maulik Shah <mkshah@...eaurora.org>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] gpiolib: irq hooks: fix recursion in gpiochip_irq_unmask

irqchip shared with multiple gpiochips, leads to recursive call of
gpiochip_irq_mask/gpiochip_irq_unmask which was assigned to
rqchip->irq_mask/irqchip->irq_unmask, these happens becouse of
only irqchip->irq_enable == gpiochip_irq_enable is checked.

Let's add an additional check to make sure shared irqchip is detected
even if irqchip->irq_enable wasn't defined.

Fixes: a8173820f441 ("gpio: gpiolib: Allow GPIO IRQs to lazy disable")
Signed-off-by: Nikita Shubin <nikita.shubin@...uefel.me>
---
 drivers/gpio/gpiolib.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 589eceecf374..5ce0c14c637b 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1419,7 +1419,8 @@ static void gpiochip_set_irq_hooks(struct gpio_chip *gc)
 	if (WARN_ON(gc->irq.irq_enable))
 		return;
 	/* Check if the irqchip already has this hook... */
-	if (irqchip->irq_enable == gpiochip_irq_enable) {
+	if (irqchip->irq_enable == gpiochip_irq_enable ||
+		irqchip->irq_mask == gpiochip_irq_mask) {
 		/*
 		 * ...and if so, give a gentle warning that this is bad
 		 * practice.
-- 
2.26.2