linux-kernel - Re: [PATCH 6/6] regulator: core: simplify lock

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Message-ID: <CAE-0n51gcN+3Ng7+bz21eS_6JomnVDzZMuWyzZVB25paj29j4g@mail.gmail.com>
Date:   Tue, 29 Aug 2023 15:52:19 -0500
From:   Stephen Boyd <swboyd@...omium.org>
To:     Doug Anderson <dianders@...omium.org>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>, linux-kernel@...r.kernel.org,
        Dmitry Osipenko <digetx@...il.com>
Subject: Re: [PATCH 6/6] regulator: core: simplify lock_two()

Quoting Michał Mirosław (2023-08-28 13:26:54)
> Indeed they are quite similar. I did remove a bit more code than that,
> though: in this case there is no early success return before the loop.
>
> Instead of saying:
>
> lock A
> lock B
> if ok return
> if that failed, loop:
>   unlock A
>   lock B harder
>   lock A
>   if ok return
>   swap A <-> B
>   lock B
>
> Now it's:
>
> lock A
> loop forever:
>   lock B
>   if ok, return
>   unlock A
>   swap them
>   lock A harder
>
> With the same condition 'A held' at the start of an iteration.
>

Removing duplicate code is great! I'm primarily concerned with
readability. The terms 'A' and 'B' doesn't make it easy for me. Can you
maintain the 'held' and 'contended' names for the variables?

That would be

 lock 'held'
 loop forever:
   lock 'contended'
   if ok, return
   unlock 'held'
   swap them
   lock 'held' harder

per the psuedo-code.