Messages in this thread | | | Date | Fri, 2 Dec 2022 17:44:58 +0200 | From | Andy Shevchenko <> | Subject | Re: [PATCH v7 2/2] gpiolib: protect the GPIO device against being dropped while in use by user-space |
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On Fri, Dec 02, 2022 at 04:04:44PM +0100, Bartosz Golaszewski wrote: > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> > > While any of the GPIO cdev syscalls is in progress, the kernel can call > gpiochip_remove() (for instance, when a USB GPIO expander is disconnected) > which will set gdev->chip to NULL after which any subsequent access will > cause a crash. > > To avoid that: use an RW-semaphore in which the syscalls take it for > reading (so that we don't needlessly prohibit the user-space from calling > syscalls simultaneously) while gpiochip_remove() takes it for writing so > that it can only happen once all syscalls return. > > Fixes: d7c51b47ac11 ("gpio: userspace ABI for reading/writing GPIO lines") > Fixes: 3c0d9c635ae2 ("gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL") > Fixes: aad955842d1c ("gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and GPIO_V2_GET_LINEINFO_WATCH_IOCTL") > Fixes: a54756cb24ea ("gpiolib: cdev: support GPIO_V2_LINE_SET_CONFIG_IOCTL") > Fixes: 7b8e00d98168 ("gpiolib: cdev: support GPIO_V2_LINE_SET_VALUES_IOCTL") > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> > [Nick: fixed a build failure with CDEV_V1 disabled]
> Co-authored-by: Nick Hainke <vincent@systemli.org>
In Linux kernel there is no such tag. And in case you want to use Co-developed-by, you also need to add the respective SoB one.
> Reviewed-by: Kent Gibson <warthog618@gmail.com> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
-- With Best Regards, Andy Shevchenko
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