[alsa-devel] [RFC PATCH 1/2] regmap: add configurable lock class key for lockdep

[Mark Brown]

On Thu, Jun 25, 2015 at 05:03:00PM +0200, Lars-Peter Clausen wrote:
> On 06/25/2015 03:21 PM, Arjan van de Ven wrote:

> >wouldn't it be better to use the mutex_lock_nested() and co to explicitly
> >express your hierarchy?

> That would require that the hierarchy is known in advance. The hierarchy
> depends on the hardware topology. Different systems will have different
> hierarchies where the relationship between locks can change and it will be
> hard to find a hierarchy that works across all topologies.

It depends on what you use as the key for the nested locking stuff.  If
you assign a key per regmap (casting the pointer to an integer, using an
IDR or something).  I don't know if that creates problems for the
locking code, I'd not expect so but then I'd not have expected the
problem in the first place.

As far as I can tell we're likely to end up needing a key per regmap or
something similar.
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