| Message ID | 20200121001216.15964-1-dan.callaghan@opengear.com |
|---|---|
| State | New |
| Headers | show |
| Series | [RESEND] gpiolib: hold gpio devices lock until ->descs array is initialised | expand |
On Tue, Jan 21, 2020 at 1:13 AM Dan Callaghan <dan.callaghan@opengear.com> wrote: > 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> > --- > Resending this one because I failed to cc the maintainers on the > original posting, sorry about that. This makes a lot of sense, I'm impressed that you managed to provoke this error! Patch applied. Yours, Linus Walleij
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 78a16e42f222..33c72fb12bb5 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1495,11 +1495,11 @@ 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
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> --- Resending this one because I failed to cc the maintainers on the original posting, sorry about that. drivers/gpio/gpiolib.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)