Re: [linux-pm] [GIT PULL] One more power management fix for 2.6.37

From: Dominik Brodowski
Date: Wed Nov 03 2010 - 17:19:05 EST


> There's apparently an ordering problem with dpm_list_mtx and
> socket->skt_mutex. Lockdep details appended.
>
> Dominik, Rafael? What's the proper locking order here, and
> how do we fix this?

Thanks for noting this; let's see:

- We add a PCMCIA device holding skt_mutex, therefore we have the ordering
(1) skt_mutex -> (2) dpm_list_mtx

- If we're suspending, dpm_list_mtx is held, but we need to acquire
skt_mutex as we modify some data being protected by skt_mutex
(1) dpm_list_mtx -> (2) skt_mutex

Rafael, any idea on how to solve this? How do other subsystems handle such
an issue? Do they call device_add() with no locks held at all?

Best,
Dominik
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