[PATCH v4 0/7] iio: core: Introduce cleanup.h support for mode locks

[Kurt Borja <kuurtb@gmail.com>]

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>
---
v4:

  - 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: c30e80d68a7afb334fde7147ee0106f25dd58d3a
change-id: 20251130-lock-impr-6f22748c15e8

-- 
 ~ Kurt