[PATCH] gpio: tegra186: Fix chip_data type confusion

[PATCH] gpio: tegra186: Fix chip_data type confusion

[Marc Zyngier]

The tegra186 GPIO driver makes the assumption that the pointer
returned by irq_data_get_irq_chip_data() is a pointer to a
tegra_gpio structure. Unfortunately, it is actually a pointer
to the inner gpio_chip structure, as mandated by the gpiolib
infrastructure. Nice try.

The saving grace is that the gpio_chip is the first member of
tegra_gpio, so the bug has gone undetected since... forever.

Fix it by performing a container_of() on the pointer. This results
in no additional code, and makes it possible to understand how
the whole thing works.

Fixes: 5b2b135a87fc ("gpio: Add Tegra186 support")
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: Thierry Reding <treding@nvidia.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 drivers/gpio/gpio-tegra186.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpio-tegra186.c b/drivers/gpio/gpio-tegra186.c
index 34b36a8c035f..8d298beffd86 100644
--- a/drivers/gpio/gpio-tegra186.c
+++ b/drivers/gpio/gpio-tegra186.c
@@ -343,9 +343,12 @@ static int tegra186_gpio_of_xlate(struct gpio_chip *chip,
 	return offset + pin;
 }
 
+#define to_tegra_gpio(x) container_of((x), struct tegra_gpio, gpio)
+
 static void tegra186_irq_ack(struct irq_data *data)
 {
-	struct tegra_gpio *gpio = irq_data_get_irq_chip_data(data);
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
+	struct tegra_gpio *gpio = to_tegra_gpio(gc);
 	void __iomem *base;
 
 	base = tegra186_gpio_get_base(gpio, data->hwirq);
@@ -357,7 +360,8 @@ static void tegra186_irq_ack(struct irq_data *data)
 
 static void tegra186_irq_mask(struct irq_data *data)
 {
-	struct tegra_gpio *gpio = irq_data_get_irq_chip_data(data);
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
+	struct tegra_gpio *gpio = to_tegra_gpio(gc);
 	void __iomem *base;
 	u32 value;
 
@@ -372,7 +376,8 @@ static void tegra186_irq_mask(struct irq_data *data)
 
 static void tegra186_irq_unmask(struct irq_data *data)
 {
-	struct tegra_gpio *gpio = irq_data_get_irq_chip_data(data);
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
+	struct tegra_gpio *gpio = to_tegra_gpio(gc);
 	void __iomem *base;
 	u32 value;
 
@@ -387,7 +392,8 @@ static void tegra186_irq_unmask(struct irq_data *data)
 
 static int tegra186_irq_set_type(struct irq_data *data, unsigned int type)
 {
-	struct tegra_gpio *gpio = irq_data_get_irq_chip_data(data);
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
+	struct tegra_gpio *gpio = to_tegra_gpio(gc);
 	void __iomem *base;
 	u32 value;
 
-- 
2.34.1

Re: [PATCH] gpio: tegra186: Fix chip_data type confusion

[Linus Walleij]

On Fri, Feb 11, 2022 at 10:39 AM Marc Zyngier <maz@kernel.org> wrote:

> The tegra186 GPIO driver makes the assumption that the pointer
> returned by irq_data_get_irq_chip_data() is a pointer to a
> tegra_gpio structure. Unfortunately, it is actually a pointer
> to the inner gpio_chip structure, as mandated by the gpiolib
> infrastructure. Nice try.
>
> The saving grace is that the gpio_chip is the first member of
> tegra_gpio, so the bug has gone undetected since... forever.
>
> Fix it by performing a container_of() on the pointer. This results
> in no additional code, and makes it possible to understand how
> the whole thing works.
>
> Fixes: 5b2b135a87fc ("gpio: Add Tegra186 support")
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> Cc: Thierry Reding <treding@nvidia.com>
> Cc: Linus Walleij <linus.walleij@linaro.org>
> Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Patch applied for fixes.

Yours,
Linus Walleij