Re: [PATCH v5 0/7] iio: core: Introduce cleanup.h support for mode locks

Jonathan Cameron
2026-01-22T19:16:58Z

On Tue, 20 Jan 2026 01:20:40 -0500
Kurt Borja <kuurtb@gmail.com> wrote:

> 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>
I've queued this up. For now it'll just be pushed out on the testing branch.
Hopefully the new noise from sparse won't bother anyone too much.

Jonathan

> ---
> v5:
>
> - Fix all function/macro names in kernel-doc
>
> v4: https://lore.kernel.org/r/20260118-lock-impr-v4-0-6c8d0aee8ed2@gmail.com
>
> - Replace "," with ";" in __iio_dev_mode_lock() docs.
>
> - Fix "bellow" -> "below" typo.
>
> - Drop first example in IIO_DEV_ACQUIRE_DIRECT_MODE() docs.
>
> - Match variable names in kernel-doc and definitions.
>
> - Replace "markings" with "annotations" in the "static inline" remark
>
> - Replace "claim_ptr" with "claim" in IIO_DEV_ACQUIRE_FAILED() and get
> the pointer inside.
>
> v3: https://lore.kernel.org/r/20260106-lock-impr-v3-0-1db909b192c0@gmail.com
>
> - 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 | 139 +++++++++++++++++++--
> 8 files changed, 190 insertions(+), 184 deletions(-)
> ---
> base-commit: eab91f819af428173f7e0aa1c80b3e561c3707bb
> change-id: 20251130-lock-impr-6f22748c15e8
>