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

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Message-Id: <DFRTDXTFAYGT.46CY6IJICG4W@gmail.com>
Date: Sun, 18 Jan 2026 10:19:09 -0500
From: "Kurt Borja" <kuurtb@...il.com>
To: Nuno Sá <noname.nuno@...il.com>, "Kurt Borja"
 <kuurtb@...il.com>, "Andy Shevchenko" <andriy.shevchenko@...el.com>,
 "Lars-Peter Clausen" <lars@...afoo.de>, "Michael Hennerich"
 <Michael.Hennerich@...log.com>, "Jonathan Cameron" <jic23@...nel.org>,
 "Benson Leung" <bleung@...omium.org>, "Antoniu Miclaus"
 <antoniu.miclaus@...log.com>, "Gwendal Grignou" <gwendal@...omium.org>,
 "Shrikant Raskar" <raskar.shree97@...il.com>, "Per-Daniel Olsson"
 <perdaniel.olsson@...s.com>
Cc: "David Lechner" <dlechner@...libre.com>, Nuno Sá
 <nuno.sa@...log.com>, "Andy Shevchenko" <andy@...nel.org>, "Guenter Roeck"
 <groeck@...omium.org>, "Jonathan Cameron" <Jonathan.Cameron@...wei.com>,
 <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
 <chrome-platform@...ts.linux.dev>
Subject: Re: [PATCH v3 0/7] iio: core: Introduce cleanup.h support for mode
 locks

On Sun Jan 18, 2026 at 5:00 AM -05, Nuno Sá wrote:
> On Tue, 2026-01-06 at 03:06 -0500, Kurt Borja 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@...il.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
>
> Nothing to add from me...
>
> Reviewed-by: Nuno Sá <nuno.sa@...log.com>

Thank you for your feedback, Nuno!

-- 
Thanks,
 ~ Kurt