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    SubjectRe: [RFC][PATCH 0/8] PM: Implement autosleep and "wake locks"
    On Mon, Feb 6, 2012 at 5:00 PM, Rafael J. Wysocki <> wrote:
    > All in all, it's not as much code as I thought it would be and it seems to be
    > relatively simple (which rises the question why the Android people didn't
    > even _try_ to do something like this instead of slapping the "real" wakelocks
    > onto the kernel FWIW).  IMHO it doesn't add anything really new to the kernel,
    > except for the user space interfaces that should be maintainable.  At least I
    > think I should be able to maintain them. :-)

    Replacing a working solution with an untested one takes time. That
    said, I have recently tried replacing all our kernel wake-locks with a
    thin wrapper around wake-sources. This appears to mostly work, but the
    wake-source timeout feature has some bugs or incompatible apis. An
    init api would also be useful for embedding wake-sources in other data
    structures without adding another memory allocation. Your patch to
    move the spinlock init to wakeup_source_add still require the struct
    to be zero initialized and the name set manually.

    I needed to use two wake-sources per wake-lock since calling
    __pm_stay_awake after __pm_wakeup_event on a wake-source does not
    cancel the timeout. Unless there is a reason to keep this behavior I
    would like __pm_stay_awake to cancel any active timeout.

    Destroying a wake-source also has some problems. If you call
    wakeup_source_destroy it will spin forever if the wake-source is
    active without a timeout. And, if you call __pm_relax then
    wakeup_source_destroy it could free the wake-source memory while the
    timer function is still running. It also looks as if the wake_source
    can be immediately deactivated if you call __pm_wakeup_event at the
    same time as the previous timeout expired.

    Arve Hjønnevåg
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      Last update: 2012-02-14 03:09    [W:0.042 / U:12.940 seconds]
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