Messages in this thread | | | From | Linus Walleij <> | Date | Wed, 31 Jan 2024 21:19:30 +0100 | Subject | Re: [PATCH 16/22] gpio: reduce the functionality of validate_desc() |
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On Wed, Jan 31, 2024 at 9:16 PM Linus Walleij <linus.walleij@linaroorg> wrote: > On Tue, Jan 30, 2024 at 1:48 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote: > > > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> > > > > Checking desc->gdev->chip for NULL without holding it in place with some > > serializing mechanism is pointless. Remove this check. Also don't check > > desc->gdev for NULL as it can never happen. > > > > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> > > I don't know if I agree that it is pointless. It will work on any single-CPU > system and 99.9% of other cases. > > On the other hand: what it is supposed to protect against is userspace > doing calls to a gpio_device through the character device, while the > backing struct gpio_chip is gone (e.g. a GPIO expander on USB, > and someone pulled the cable), i.e. it became NULL, and this is why the > error message says "backing device is gone". > > But I want to see where the series is going, maybe you fix this > problem in the end, so I can come back and ACK this.
Aha, it is fixed in patches 19+20. Maybe mention that we add a new protection later in the series in the commit message?
Anyway, I get it now!
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Yours, Linus Walleij
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