[PATCH v3 0/7] iio: core: Introduce cleanup.h support for mode locks

Kurt Borja
2026-01-06T08:07:10Z

Hi,

In a recent driver review discussion [1], Andy Shevchenko suggested we
add cleanup.h support for the lock API:

iio_device_claim_{direct,buffer_mode}().

Which would allow some nice code simplification in many places. Some
examples are given as patches, but the last two are the biggest
differences.

In this version I dropped the RFC tag, as the general feeling is to go
through with this after some modifications. Main one is the addition of
IIO_DEV_ACQUIRE_{BUFFER,CLAIM}_MODE() wrappers to avoid drivers using
the guard classes directly. I also added comments on the forbidden ways
to use this API but I definitely still take suggestions on this.

For now I dropped iio_device_claim_buffer_mode() rename, as this point
is still being discussed. My suggestion based on the RFC discussion is
to do it, but in a separate patch (using coccinelle) and while we're at
it rename the whole API like this:

iio_dev_mode_lock()
iio_dev_mode_direct_trylock()
iio_dev_mode_buffer_trylock()
iio_dev_mode_unlock()

Let me know what you think and thanks for taking a look!

Signed-off-by: Kurt Borja <kuurtb@gmail.com>
---
v3:

- Reword commit message of patch 1: infallible -> unconditional.

- Drop "*strongly*" in __iio_dev_mode_lock() kernel-doc and be a bit
more clear on the function's intention.

- Keep comment about inline functions and sparse markings, but drop
the __cond_acquires() part, as the new implementation makes it
unnecessary.

- Implement iio_device_release_*() as macros around
__iio_dev_mode_unlock().

- Rename iio_device_claim_buffer_mode() ->
iio_device_try_claim_buffer_mode() to avoid silently breaking
out-of-tree drivers.

- Drop the `_` argument prefix in new macros, as there are no name
conflicts.

- Drop "dummy" from IIO_DEV_ACQUIRE_DIRECT_MODE kernel-doc, as the
`claim` variable does store the error value.

- Drop IIO_DEV_ACQUIRE_BUFFER_MODE() until a driver actually needs it.

- Rename IIO_DEV_ACQUIRE_ERR() -> IIO_DEV_ACQUIRE_FAILED() to make the
name more clear.

- Rename IIO_DEV_GUARD_ANY_MODE() -> IIO_DEV_GUARD_CURRENT_MODE() to
make the name more clear.

- Add missing . in iio_device_release_direct() kernel-doc.

NOTE: Andy suggested __iio_dev_mode_*() be exported into the IIO_CORE
namespace. However, this cannot be done because these functions
need to be called inline, so Sparse can see the __acquires() and
__releases() tags.

Happy new year to everyone :)

v2: https://lore.kernel.org/r/20251211-lock-impr-v2-0-6fb47bdaaf24@gmail.com

- Add __iio_dev_mode_lock() (formerly iio_device_claim()) in the first
patch.

- Added comments to make sure __iio_dev_mode_lock() is not used by
drivers to protect internal state, or in general.

- Add patch which re-implements iio_device_claim_direct() using
__iio_dev_mode_lock().

- Match iio_device_claim_buffer_mode() semantics by reimplementing it
in the same way as iio_device_claim_direct().

- Guard classes now are prefixed with __priv__ to make sure drivers
don't use them directly.

- Add IIO_DEV_ACQUIRE_{BUFFER,DIRECT}_MODE() documented wrappers

- Avoid any function renames (for now).

- Rename dummy variable `claim` instead of `busy` on vcnl4000 patch.

- Avoid scoped guard in max30102.

- Keep using iio_trigger_validate_own_device() insted of
iio_trigger_using_own() in opt4060.

v1: https://lore.kernel.org/r/20251203-lock-impr-v1-0-b4a1fd639423@gmail.com

---
Kurt Borja (7):
iio: core: Add and export __iio_dev_mode_lock()
iio: core: Refactor iio_device_claim_direct() implementation
iio: core: Match iio_device_claim_*() semantics and implementation
iio: core: Add cleanup.h support for iio_device_claim_*()
iio: light: vcnl4000: Use IIO cleanup helpers
iio: health: max30102: Use IIO cleanup helpers
iio: light: opt4060: Use IIO cleanup helpers

drivers/iio/adc/ade9000.c | 2 +-
.../common/cros_ec_sensors/cros_ec_sensors_core.c | 5 +-
drivers/iio/health/max30100.c | 8 +-
drivers/iio/health/max30102.c | 33 ++---
drivers/iio/industrialio-core.c | 86 +++---------
drivers/iio/light/opt4060.c | 52 +++-----
drivers/iio/light/vcnl4000.c | 49 +++----
include/linux/iio/iio.h | 145 +++++++++++++++++++--
8 files changed, 196 insertions(+), 184 deletions(-)
---
base-commit: fb2f4eb29a258145b0336601f00509cab6e93e7c
change-id: 20251130-lock-impr-6f22748c15e8

--
~ Kurt