Re: [patch update] PM: Introduce core framework for run-time PM of I/O devices (rev. 6)

Alan Stern
2009-06-26T21:13:29Z

On Fri, 26 Jun 2009, Rafael J. Wysocki wrote:

> > It occurs to me that the problem would be solved if were a cancel_work
> > routine. In the same vein, it ought to be possible for
> > cancel_delayed_work to run in interrupt context. I'll see what can be
> > done.
>
> Having looked at the workqueue code I'm not sure if there's a way to implement
> that in a non-racy way. Which may be the reason why there are no such
> functions already. :-)

Well, I'll give it a try.

Speaking of races, have you noticed that the way power.work_done gets
used is racy? You can't wait for the completion before releasing the
lock, but then anything could happen.

A safer approach would be to use a wait_queue.

> In the meantime I reworked the patch (below) to use more RPM_* flags and I
> removed the runtime_break and runtime_notify bits from it. Also added some
> comments to explain some non-obvious steps (hope that helps).
>
> I also added the pm_runtime_put_atomic() and pm_runtime_put() as per the
> comment above.
>
> It seems to be a bit cleaner this way, but that's my personal view. :-)

I'll look at it over the weekend. And I'll try to see if proper
cancel_work and cancel_delayed_work functions can help clean it up.

Alan Stern