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

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Message-ID: <20260116203353.59a2a00e@jic23-huawei>
Date: Fri, 16 Jan 2026 20:33:53 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Kurt Borja <kuurtb@...il.com>
Cc: Andy Shevchenko <andriy.shevchenko@...el.com>, Lars-Peter Clausen
 <lars@...afoo.de>, Michael Hennerich <Michael.Hennerich@...log.com>, 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>,
 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 Tue, 06 Jan 2026 03:06:55 -0500
Kurt Borja <kuurtb@...il.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()

I'm not a huge fan of flag days though this is entirely in direct mode
so I can just do it at the start of a cycle.

Anyhow, that's a job for another day where we can bikeshed the naming
yet again.

I do like unifying the unlock though.

Patch 5 never made the list for some reason.
https://lore.kernel.org/all/20260106-lock-impr-v3-0-1db909b192c0@gmail.com/#r

(I thought I'd accidentally deleted it!)

Thanks

Jonathan


> 
> 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
>