linux-kernel - [PATCH 4.9 037/120] gpio: Move freeing of GPIO hogs before numbing of the device

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Date:   Wed, 18 Jan 2017 11:45:55 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Geert Uytterhoeven <geert@...ux-m68k.org>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: [PATCH 4.9 037/120] gpio: Move freeing of GPIO hogs before numbing of the device

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Geert Uytterhoeven <geert@...ux-m68k.org>

commit 5018ada69a04c8ac21d74bd682fceb8e42dc0f96 upstream.

When removing a gpiochip that uses GPIO hogging (e.g. by unloading the
chip's DT overlay), a warning is printed:

    gpio gpiochip8: REMOVING GPIOCHIP WITH GPIOS STILL REQUESTED

This happens because gpiochip_free_hogs() is called after the gdev->chip
pointer is reset to NULL. Hence __gpiod_free() cannot determine the
chip in use, and cannot clear flags nor call the optional chip-specific
.free() callback.

Move the call to gpiochip_free_hogs() up to fix this.

Fixes: ff2b135922992756 ("gpio: make the gpiochip a real device")
Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpio/gpiolib.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1317,12 +1317,12 @@ void gpiochip_remove(struct gpio_chip *c
 
 	/* FIXME: should the legacy sysfs handling be moved to gpio_device? */
 	gpiochip_sysfs_unregister(gdev);
+	gpiochip_free_hogs(chip);
 	/* Numb the device, cancelling all outstanding operations */
 	gdev->chip = NULL;
 	gpiochip_irqchip_remove(chip);
 	acpi_gpiochip_remove(chip);
 	gpiochip_remove_pin_ranges(chip);
-	gpiochip_free_hogs(chip);
 	of_gpiochip_remove(chip);
 	/*
 	 * We accept no more calls into the driver from this point, so