[PATCH v9 0/9] drivers/base: Introduce revocable

Tzung-Bi Shih
2026-04-27T13:59:29Z

This series introduces the "revocable" mechanism, a synchronization
primitive designed to prevent Use-After-Free errors.

- Patch 1 introduces the revocable which is an implementation of ideas
from the talk [1].

- Patch 2 adds KUnit test cases.

- Patches 3 to 7 transitions the UAF prevention logic within the GPIO
core (gpiolib) to use the "revocable" mechanism.

The existing code aims to prevent UAF issues when the underlying GPIO
chip is removed. They replace that custom logic with the generic
"revocable" API, which is designed to handle such lifecycle
dependencies. There should be no changes in behavior.

- Patches 8 to 9 uses "revocable" mechanism to fix an UAF in
cros_ec_chardev driver. Alternatively, [2] is a series for fixing the
same issue without using "revocable".

Since v9, there are two ways to manage the resource provider handle.
- Embedded allocation: patches 3 to 7 might be the potential user.
- Dynamic allocation: patches 8 to 9 might be the potential user.

[1] https://lpc.events/event/17/contributions/1627/
[2] https://lore.kernel.org/all/20260427134659.95181-1-tzungbi@kernel.org

---
v9:
- Rebase onto v7.1-rc1.
- Remove the selftests patch as it makes less sense to test revocable
APIs via kselftests.
- Merge patches 7 to 11 from
https://lore.kernel.org/all/20260213092958.864411-1-tzungbi@kernel.org
into the series.
- Merge patch from
https://lore.kernel.org/all/20250923075302.591026-5-tzungbi@kernel.org
- Merge patch from
https://lore.kernel.org/all/20250912081718.3827390-6-tzungbi@kernel.org

v8: https://lore.kernel.org/all/20260213092307.858908-1-tzungbi@kernel.org
- Rework on the revocable APIs. See changelog in [PATCH v8 1/3] for details.

v7: https://lore.kernel.org/all/20260116080235.350305-1-tzungbi@kernel.org
- Rebase onto next-20260115.

v6: https://lore.kernel.org/all/20251106152330.11733-1-tzungbi@kernel.org
- Rebase onto next-20251106.
- Separate revocable core and use cases.

v5: https://lore.kernel.org/all/20251016054204.1523139-1-tzungbi@kernel.org
- Rebase onto next-20251015.
- Add more context about the PoC.
- Support multiple revocable providers in the PoC.

v4: https://lore.kernel.org/all/20250923075302.591026-1-tzungbi@kernel.org
- Rebase onto next-20250922.
- Remove the 5th patch from v3.
- Add fops replacement PoC in 5th - 7th patches.

v3: https://lore.kernel.org/all/20250912081718.3827390-1-tzungbi@kernel.org
- Rebase onto https://lore.kernel.org/all/20250828083601.856083-1-tzungbi@kernel.org
and next-20250912.
- The 4th patch changed accordingly.

v2: https://lore.kernel.org/all/20250820081645.847919-1-tzungbi@kernel.org
- Rename "ref_proxy" -> "revocable".
- Add test cases in Kunit and selftest.

v1: https://lore.kernel.org/all/20250814091020.1302888-1-tzungbi@kernel.org

Tzung-Bi Shih (9):
revocable: Revocable resource management
revocable: Add KUnit test cases
gpio: Add revocable provider handle for struct gpio_chip
gpio: cdev: Leverage revocable for accessing struct gpio_chip
gpio: Remove gpio_chip_guard by using revocable
gpio: Leverage revocable for accessing struct gpio_chip
gpio: Remove unused `chip` and `srcu` in struct gpio_device
platform/chrome: Protect cros_ec_device lifecycle with revocable
platform/chrome: cros_ec_chardev: Consume cros_ec_device via revocable

.../driver-api/driver-model/index.rst | 1 +
.../driver-api/driver-model/revocable.rst | 384 +++++++++++++++
MAINTAINERS | 10 +
drivers/base/Kconfig | 5 +
drivers/base/Makefile | 5 +-
drivers/base/revocable.c | 298 +++++++++++
drivers/base/revocable_test.c | 461 ++++++++++++++++++
drivers/gpio/gpiolib-cdev.c | 77 ++-
drivers/gpio/gpiolib-sysfs.c | 31 +-
drivers/gpio/gpiolib.c | 255 ++++------
drivers/gpio/gpiolib.h | 28 +-
drivers/platform/chrome/cros_ec.c | 11 +
drivers/platform/chrome/cros_ec_chardev.c | 80 ++-
include/linux/platform_data/cros_ec_proto.h | 3 +
include/linux/revocable.h | 214 ++++++++
15 files changed, 1597 insertions(+), 266 deletions(-)
create mode 100644 Documentation/driver-api/driver-model/revocable.rst
create mode 100644 drivers/base/revocable.c
create mode 100644 drivers/base/revocable_test.c
create mode 100644 include/linux/revocable.h

--
2.51.0