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gpiolib: hold gpio devices lock until ->descs array is initialised 

If a driver consuming the GPIO chip is being probed at the same time as
the GPIO driver is registering the chip, it is possible for the
consuming driver to see the ->descs array in an uninitialised state.
For example, the gpio-keys-polled driver can fail like this:

    kernel: gpiod_request: invalid GPIO (no device)
    kernel: gpio-keys-polled PRP0001:07: failed to get gpio: -22
    kernel: gpio-keys-polled: probe of PRP0001:07 failed with error -22

This patch makes gpiochip_add() hold the lock protecting gpio_devices
until it has finished setting desc->gdev on the newly inserted list
entry.

Signed-off-by: Dan Callaghan <dan.callaghan@opengear.com>
Link: https://lore.kernel.org/r/20200121001216.15964-1-dan.callaghan@opengear.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Dan Callaghan 2020-01-21 10:12:17 +10:00 committed by Linus Walleij
parent 0d311d8b93
commit 207270dd0b
1 changed files with 2 additions and 2 deletions
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4
drivers/gpio/gpiolib.c
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@ -1486,11 +1486,11 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
goto err_free_label;
}
spin_unlock_irqrestore(&gpio_lock, flags);
for (i = 0; i < chip->ngpio; i++)
gdev->descs[i].gdev = gdev;
spin_unlock_irqrestore(&gpio_lock, flags);
#ifdef CONFIG_PINCTRL
INIT_LIST_HEAD(&gdev->pin_ranges);
#endif