[PATCH 0/3] gpiolib: add reference counting to GPIO descriptors

[Bartosz Golaszewski <brgl@bgdev.pl>]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

This was: nvmem/gpio: fix resource management.

These are the remaining patches from the series aimed at fixing resource
management problems in nvmem.

The first one adds a new descriptor validation macro. The second uses kref to
add reference counting to GPIO descriptors. The last one fixes a potential
use-after-free problem in nvmem.

The last change should actually go into v5.6 but it depends on a new feature.
I'm not sure how to go about applying this.

Changes in patch 2/3 since the last submission:
- add a stub for when GPIOLIB is not selected
- use might_sleep() in gpiod_put() as we may not necessarily call gpiod_free()
  every time now (where it would have been called normally) depending on the
  reference count

Bartosz Golaszewski (3):
  gpiolib: provide VALIDATE_DESC_PTR() macro
  gpiolib: use kref in gpio_desc
  nvmem: increase the reference count of a gpio passed over config

 drivers/gpio/gpiolib.c        | 48 ++++++++++++++++++++++++++++++++---
 drivers/gpio/gpiolib.h        |  1 +
 drivers/nvmem/core.c          |  2 +-
 include/linux/gpio/consumer.h |  9 +++++++
 4 files changed, 55 insertions(+), 5 deletions(-)

-- 
2.25.0