linux-kernel - [PATCH v2] gpiolib: Fix irq_domain resource tracking for gpiochip_irqchip_add

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Message-Id: <20230616-fixes-gpiolib-irq-domain-v2-1-e28b47fc3e45@kernel.org>
Date:   Mon, 19 Jun 2023 10:56:07 +0200
From:   Michael Walle <mwalle@...nel.org>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Andy Shevchenko <andy@...nel.org>
Cc:     linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jiawen Wu <jiawenwu@...stnetic.com>,
        Michael Walle <mwalle@...nel.org>
Subject: [PATCH v2] gpiolib: Fix irq_domain resource tracking for
 gpiochip_irqchip_add_domain()

Up until commit 6a45b0e2589f ("gpiolib: Introduce
gpiochip_irqchip_add_domain()") all irq_domains were allocated
by gpiolib itself and thus gpiolib also takes care of freeing it.

With gpiochip_irqchip_add_domain() a user of gpiolib can associate an
irq_domain with the gpio_chip. This irq_domain is not managed by
gpiolib and therefore must not be freed by gpiolib.

Fixes: 6a45b0e2589f ("gpiolib: Introduce gpiochip_irqchip_add_domain()")
Reported-by: Jiawen Wu <jiawenwu@...stnetic.com>
Signed-off-by: Michael Walle <mwalle@...nel.org>
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
Reviewed-by: Andy Shevchenko <andy@...nel.org>
---
Changes in v2:
- change flag name to domain_is_externally_allocated
- Link to v1: https://lore.kernel.org/r/20230616-fixes-gpiolib-irq-domain-v1-1-27fe870db961@kernel.org
---
 drivers/gpio/gpiolib.c      | 3 ++-
 include/linux/gpio/driver.h | 8 ++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 7c6fefcbebd1..2664275c25f3 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1740,7 +1740,7 @@ static void gpiochip_irqchip_remove(struct gpio_chip *gc)
 	}
 
 	/* Remove all IRQ mappings and delete the domain */
-	if (gc->irq.domain) {
+	if (!gc->irq.domain_is_allocated_externally && gc->irq.domain) {
 		unsigned int irq;
 
 		for (offset = 0; offset < gc->ngpio; offset++) {
@@ -1786,6 +1786,7 @@ int gpiochip_irqchip_add_domain(struct gpio_chip *gc,
 
 	gc->to_irq = gpiochip_to_irq;
 	gc->irq.domain = domain;
+	gc->irq.domain_is_allocated_externally = true;
 
 	/*
 	 * Using barrier() here to prevent compiler from reordering
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 5c6db5533be6..67b8774eed8f 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -251,6 +251,14 @@ struct gpio_irq_chip {
 	 */
 	bool initialized;
 
+	/**
+	 * @domain_is_allocated_externally:
+	 *
+	 * True it the irq_domain was allocated outside of gpiolib, in which
+	 * case gpiolib won't free the irq_domain itself.
+	 */
+	bool domain_is_allocated_externally;
+
 	/**
 	 * @init_hw: optional routine to initialize hardware before
 	 * an IRQ chip will be added. This is quite useful when

---
base-commit: 659140df086c67f5eb77bbffcab34a7e8accd2a8
change-id: 20230616-fixes-gpiolib-irq-domain-2b69ecae0fdd