Messages in this thread | | | From | Linus Torvalds <> | Date | Sun, 12 Dec 2010 17:34:12 -0800 | Subject | Re: [RFC][PATCH 2/4] PM: Remove redundant checks from core device resume routines |
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So I really like this series not only because it implements what I suggested, but also because each patch seems to remove more lines than it adds. That's always nice, and much too unusual.
But in this one, I really think you should simplify/clarify things further:
On Sun, Dec 12, 2010 at 4:31 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote: > > +++ linux-2.6/drivers/base/power/main.c > @@ -485,20 +485,17 @@ void dpm_resume_noirq(pm_message_t state > transition_started = false; > while (!list_empty(&dpm_noirq_list)) { > struct device *dev = to_device(dpm_noirq_list.next); > + int error; > > get_device(dev); > - if (dev->power.status > DPM_OFF) { > - int error; > - > - dev->power.status = DPM_OFF; > - mutex_unlock(&dpm_list_mtx); > + dev->power.status = DPM_OFF; > + mutex_unlock(&dpm_list_mtx);
I think you should move the device to the dpm_suspended list _here_, before dropping the mutex. That way the power.status thing matches the list.
So then you'd just remove the crazy conditional "if it's still on a list, move it to the right list" thing, and these two lines:
> if (!list_empty(&dev->power.entry)) > list_move_tail(&dev->power.entry, &dpm_suspended_list);
Would just be that plain
list_move_tail(&dev->power.entry, &dpm_suspended_list);
before you even drop the lock. That look much simpler, and the list movement seems a lot more obvious, no?
If an unregister event (or whatever) happens while you had the mutex unlocked, it will just remove it from the new list (the one that matches the power state). So no need for that whole complexity with "what happens with the list if somebody removed the device while we were busy suspending/resuming it".
Or am I missing something?
(And same comment for that other identical case in dpm_complete())
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