[PATCH v2 0/5] gpiolib: improve concurrent access to the flags field of struct gpio_desc

[Bartosz Golaszewski]

This is a follow-up to our discussion[1] about desc->flags and possible
races with users who don't/can't synchronize with other means.

It's an attempt to use try_cmpxchg() to update only the required flags
atomically where needed + minor fixes using atomic variants of bitops
where it makes sense.

[1] https://lore.kernel.org/all/20261015153714.GA105746@rigel/

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
---
Changes in v2:
- Drop the custom gpiod_update_flags() function and use the existing
  set_mask_bits() macro instead
- Add a patch clearing debounce_period_us before GPIOD_FLAG_REQUESTED as
  suggested by Kent
- Rename the functions updating flags in gpiolib-cdev.c
- Don't rename the flags variable
- Link to v1: https://patch.msgid.link/20261104-gpio-desc-flags-atomic-v1-0-e23cedf619ba@xxxxxxxxxxxxxxxx

---
Bartosz Golaszewski (5):
      gpiolib: don't overwrite the entire flags field in gpiod_get_direction()
      gpio: shared: use atomic set_bit() for descriptor flags
      gpiolib: clear debounce period before the "requested" flag
      gpiolib: don't overwrite the entire flags field in gpiod_free_commit()
      gpio: cdev: don't overwrite the whole flags field when configuring lines

 drivers/gpio/gpiolib-cdev.c   | 111 +++++++++++++++++++++++-------------------
 drivers/gpio/gpiolib-shared.c |   6 +--
 drivers/gpio/gpiolib.c        |  36 +++++++-------
 3 files changed, 83 insertions(+), 70 deletions(-)
---
base-commit: ddfe51b0a0f5dc9e415cc2c8ad8db17532dd426b
change-id: 20261104-gpio-desc-flags-atomic-cc963a1ccfd0

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>