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    SubjectRe: [linux-pm] [GIT PULL] One more power management fix for 2.6.37
    Date
    On Wednesday, November 03, 2010, Dominik Brodowski wrote:
    > > 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?

    They usually do from what I can tell.

    Also only a few of them implement the ->suspend_noirq() callback, which is the
    one executed under dpm_list_mtx.

    What exactly is protected by skt_mutex ?

    Rafael



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