linux-kernel - Re: [PATCH v2 3/7] regulator/core: regulator_lock

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Message-ID: <ZPEXlf26YBQB4WMt@qmqm.qmqm.pl>
Date:   Fri, 1 Sep 2023 00:43:33 +0200
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Douglas Anderson <dianders@...omium.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/7] regulator/core: regulator_lock_nested: simplify
 nested locking

On Wed, Aug 30, 2023 at 01:36:38PM -0700, Stephen Boyd wrote:
> Quoting Michał Mirosław (2023-08-30 10:35:31)
> > Simplify regulator locking by removing locking around locking.
> 
> Maybe this should say "Simplify regulator_lock_nested() by removing the
> `regulator_nesting_mutex` now that rdev is locked whenever rdev->ref_cnt or
> rdev->owner are modified"?

I'll rework the message. Thanks for the hints!

[...]
> > Note: return -EALREADY is removed as no caller depends on it and in that
> > case the lock count is incremented anyway.
> 
> Where is -EALREADY removed in this patch? Perhaps "removed" should be
> "ignored"?
> 
> Note: A return value of -EALREADY from ww_mutex_lock() in
> regulator_lock_nested() is ignored as no caller depends on it.

I can actually remove this altogether: ww_mutex_lock() won't ever
return -EALREADY as it's called only if (rdev->mutex_owner != current).

Best Regards.
Michał Mirosław