| Date | Mon, 13 Feb 2012 18:07:26 -0800 | Subject | Re: [RFC][PATCH 0/8] PM: Implement autosleep and "wake locks" | From | Arve Hjønnevåg <> |
| |
On Mon, Feb 6, 2012 at 5:00 PM, Rafael J. Wysocki <rjw@sisk.pl> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|