Messages in this thread | | | Date | Tue, 15 Aug 2023 12:49:54 +0300 | From | Andy Shevchenko <> | Subject | Re: [PATCH v3] gpiolib: fix reference leaks when removing GPIO chips still in use |
| |
On Fri, Aug 11, 2023 at 09:30:34PM +0200, Bartosz Golaszewski wrote: > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> > > After we remove a GPIO chip that still has some requested descriptors, > gpiod_free_commit() will fail and we will never put the references to the > GPIO device and the owning module in gpiod_free(). > > Rework this function to: > - not warn on desc == NULL as this is a use-case on which most free > functions silently return > - put the references to desc->gdev and desc->gdev->owner unconditionally > so that the release callback actually gets called when the remaining > references are dropped by external GPIO users
...
> - if (desc && desc->gdev && gpiod_free_commit(desc)) {
The commit message doesn't explain disappearing of gdev check.
> - module_put(desc->gdev->owner); > - gpio_device_put(desc->gdev); > - } else { > + /* > + * We must not use VALIDATE_DESC_VOID() as the underlying gdev->chip > + * may already be NULL but we still want to put the references. > + */ > + if (!desc) > + return; > + > + if (!gpiod_free_commit(desc)) > WARN_ON(extra_checks); > - } > + > + module_put(desc->gdev->owner); > + gpio_device_put(desc->gdev); > }
So, if gdev can be NULL, you will get an Oops with new code.
To keep a status quo this needs to be rewritten.
-- With Best Regards, Andy Shevchenko
| |