linux-kernel - [PATCH] gpio: initialize descriptor SRCU structure before adding OF-based chips

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Message-Id: <20240212213920.49796-1-brgl@bgdev.pl>
Date: Mon, 12 Feb 2024 22:39:20 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Linus Walleij <linus.walleij@...aro.org>,
	Kent Gibson <warthog618@...il.com>,
	Alex Elder <elder@...aro.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	"Paul E . McKenney" <paulmck@...nel.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Wolfram Sang <wsa@...-dreams.de>
Cc: linux-gpio@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
	kernel test robot <lkp@...el.com>
Subject: [PATCH] gpio: initialize descriptor SRCU structure before adding OF-based chips

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

In certain situations we may end up taking the GPIO descriptor SRCU read
lock in of_gpiochip_add() before the SRCU struct is initialized. Move
the initialization before the call to of_gpiochip_add().

Fixes: be711caa87c5 ("gpio: add SRCU infrastructure to struct gpio_desc")
Fixes: 1f2bcb8c8ccd ("gpio: protect the descriptor label with SRCU")
Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-lkp/202402122228.e607a080-lkp@intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
 drivers/gpio/gpiolib.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 82811d9a4477..f5434e559382 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -991,10 +991,6 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 	if (ret)
 		goto err_cleanup_gdev_srcu;
 
-	ret = of_gpiochip_add(gc);
-	if (ret)
-		goto err_free_gpiochip_mask;
-
 	for (i = 0; i < gc->ngpio; i++) {
 		struct gpio_desc *desc = &gdev->descs[i];
 
@@ -1002,7 +998,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 		if (ret) {
 			for (j = 0; j < i; j++)
 				cleanup_srcu_struct(&gdev->descs[j].srcu);
-			goto err_remove_of_chip;
+			goto err_free_gpiochip_mask;
 		}
 
 		if (gc->get_direction && gpiochip_line_is_valid(gc, i)) {
@@ -1014,10 +1010,14 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 		}
 	}
 
-	ret = gpiochip_add_pin_ranges(gc);
+	ret = of_gpiochip_add(gc);
 	if (ret)
 		goto err_cleanup_desc_srcu;
 
+	ret = gpiochip_add_pin_ranges(gc);
+	if (ret)
+		goto err_remove_of_chip;
+
 	acpi_gpiochip_add(gc);
 
 	machine_gpiochip_add(gc);
@@ -1055,12 +1055,12 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 	gpiochip_irqchip_free_valid_mask(gc);
 err_remove_acpi_chip:
 	acpi_gpiochip_remove(gc);
-err_cleanup_desc_srcu:
-	for (i = 0; i < gdev->ngpio; i++)
-		cleanup_srcu_struct(&gdev->descs[i].srcu);
 err_remove_of_chip:
 	gpiochip_free_hogs(gc);
 	of_gpiochip_remove(gc);
+err_cleanup_desc_srcu:
+	for (i = 0; i < gdev->ngpio; i++)
+		cleanup_srcu_struct(&gdev->descs[i].srcu);
 err_free_gpiochip_mask:
 	gpiochip_remove_pin_ranges(gc);
 	gpiochip_free_valid_mask(gc);
-- 
2.40.1