linux-kernel - Re: [PATCH RFC 0/6] iio: core: Introduce cleanup.h support for mode locks

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Message-Id: <DES3YYXIH4ML.1K5X4KDG273HD@gmail.com>
Date: Sun, 07 Dec 2025 11:00:50 -0500
From: "Kurt Borja" <kuurtb@...il.com>
To: "Jonathan Cameron" <jic23@...nel.org>, "Andy Shevchenko"
 <andy.shevchenko@...il.com>
Cc: 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>, "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 RFC 0/6] iio: core: Introduce cleanup.h support for mode
 locks

On Sat Dec 6, 2025 at 1:46 PM -05, Jonathan Cameron wrote:
> On Thu, 4 Dec 2025 17:07:28 +0200
> Andy Shevchenko <andy.shevchenko@...il.com> wrote:
>
>> On Thu, Dec 4, 2025 at 4:35 PM Nuno Sá <noname.nuno@...il.com> wrote:
>> > On Wed, 2025-12-03 at 14:18 -0500, Kurt Borja wrote:  
>> > >
>> > > 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}().  
>> >
>> > We already went this patch and then reverted it. I guess before we did not had
>> > ACQUIRE() and ACQUIRE_ERR() but I'm not sure that makes it much better. Looking at the
>> > last two patches on how we are handling the buffer mode stuff, I'm really not convinced...
>> >
>> > Also, I have doubts sparse can keep up with the __cleanup stuff so I'm not sure the
>> > annotations much make sense if we go down this path. Unless we want to use both
>> > approaches which is also questionable.  
>> 
>> This, indeed, needs a (broader) discussion and I appreciate that Kurt
>> sent this RFC. Jonathan, what's your thoughts?
>
> I was pretty heavily involved in discussions around ACQUIRE() and it's use
> in CXL and runtime PM (though that's still evolving with Rafael trying
> to improve the syntax a little).  As you might guess I did have this use
> in mind during those discussions.
>
> As far as I know by avoiding the for loop complexity of the previous
> try we made and looking (under the hood) like guard() it should be much
> easier and safer to use.  Looking at this was on my list, so I'm very happy
> to see this series from Kurt exploring how it would be done.
>
> Sparse wise there is no support for now for any of the cleanup.h magic
> other than ignoring it.  That doesn't bother me that much though as these
> macros create more or less hidden local variables that are hard to mess
> with in incorrect ways.
>
> So in general I'm very much in favour of this for same reasons I jumped
> in last time (which turned out to be premature!)
>
> This will be particularly useful in avoiding the need for helper functions
> in otherwise simple code flows.

Good to hear!

Next version, after we agree on the naming approach, I'll drop the RFC
and thake all suggestions for the next version.

Thank you all for your suggestions and comments :)

>
> Jonathan


-- 
 ~ Kurt