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    SubjectRe: [PATCH 6/8] PM: Add suspend blocking work.
    From
    2010/4/27 Tejun Heo <tj@kernel.org>:
    > Hello,
    >
    >> +static void suspend_blocking_work_complete(struct suspend_blocking_work *work)
    >> +{
    >> +     unsigned long flags;
    >> +
    >> +     WARN_ON(!work->active);
    >> +     spin_lock_irqsave(&work->lock, flags);
    >> +     if (!--work->active)
    >> +             suspend_unblock(&work->suspend_blocker);
    >> +     spin_unlock_irqrestore(&work->lock, flags);
    >> +}
    >
    > Maybe work->active can be an atomic_t and the lock can be removed?
    >

    I need the spinlock to prevent the work from getting re-queued before
    suspend_unblock.

    >> +/**
    >> + * suspend_blocking_work_destroy - Destroy suspend_blocking_work
    >> + * @work: The work item in question
    >> + *
    >> + * If the work was ever queued on more then one workqueue all but the last
    >> + * workqueue must be flushed before calling suspend_blocking_work_destroy.
    >
    > As it's calling cancel_work_sync(), the above is not true.  As long as
    > no one is trying to queue it again, suspend_blocking_work_destroy() is
    > safe to call regardless of how the work has been used.
    >

    I'm not sure what the best terminology is here, but cancel_work_sync()
    only waits for work running on all the cpu-workqueues of the last
    workqueue. So, if the caller queued the work on more than one
    workqueue, suspend_blocking_work_destroy does not ensure that the
    suspend_blocking_work structure is not still in use (it should trigger
    the WARN_ON though).

    >> +void suspend_blocking_work_destroy(struct suspend_blocking_work *work)
    >> +{
    >> +     cancel_suspend_blocking_work_sync(work);
    >> +     WARN_ON(work->active);
    >> +     suspend_blocker_destroy(&work->suspend_blocker);
    >> +}
    >> +EXPORT_SYMBOL(suspend_blocking_work_destroy);
    >
    > Other than the above, it looks good to me.
    >
    > Thanks.
    >
    > --
    > tejun
    >



    --
    Arve Hjønnevåg
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