linux-kernel - [PATCH v2 3/3] gpiolib: don't double-check the gc->get callback's existence

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Message-Id: <20250226-retval-fixes-v2-3-c8dc57182441@linaro.org>
Date: Wed, 26 Feb 2025 11:12:31 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Linus Walleij <linus.walleij@...aro.org>, 
 Bartosz Golaszewski <brgl@...ev.pl>, 
 Marek Szyprowski <m.szyprowski@...sung.com>, 
 Andy Shevchenko <andriy.shevchenko@...el.com>
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Bartosz Golaszewski <bartosz.golaszewski@...aro.org>, 
 Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH v2 3/3] gpiolib: don't double-check the gc->get callback's
 existence

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

gpiochip_get() is called only in two places: in gpio_chip_get_value()
and in gpiochip_get_multiple() where the existence of the gc->get()
callback is already checked. It makes sense to unduplicate the check by
moving it one level up the stack.

Fixes: 86ef402d805d ("gpiolib: sanitize the return value of gpio_chip::get()")
Suggested-by: Andy Shevchenko <andriy.shevchenko@...el.com>
Closes: https://lore.kernel.org/all/Z7yekJ8uRh8dphKn@black.fi.intel.com/
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
 drivers/gpio/gpiolib.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 6f4efab237e6..855373eb11a8 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -3167,9 +3167,7 @@ static int gpiochip_get(struct gpio_chip *gc, unsigned int offset)
 
 	lockdep_assert_held(&gc->gpiodev->srcu);
 
-	if (!gc->get)
-		return -EIO;
-
+	/* Make sure this is called after checking for gc->get(). */
 	ret = gc->get(gc, offset);
 	if (ret > 1)
 		ret = -EBADE;
@@ -3179,7 +3177,7 @@ static int gpiochip_get(struct gpio_chip *gc, unsigned int offset)
 
 static int gpio_chip_get_value(struct gpio_chip *gc, const struct gpio_desc *desc)
 {
-	return gpiochip_get(gc, gpio_chip_hwgpio(desc));
+	return gc->get ? gpiochip_get(gc, gpio_chip_hwgpio(desc)) : -EIO;
 }
 
 /* I/O calls are only valid after configuration completed; the relevant

-- 
2.45.2