Re: [patch V2 43/67] leds/trigger/cpu: Convert to hotplug state machine

[Jacek Anaszewski]

Hi Sebastian,

On 07/15/2016 04:10 PM, Sebastian Andrzej Siewior wrote:
> * Jacek Anaszewski | 2016-07-14 13:55:26 [+0200]:
>
> > On 07/14/2016 01:33 PM, Thomas Gleixner wrote:
> > > That does not explain WHY this needs to happen in the low level bringup phase
> > > of the CPU with interrupts disabled and can't be done from the normal ONLINE
> > > callbacks in thread context.
> >
> > It was before my time in kernel, so I can only suppose that it was
> > the easiest way. Does it introduce some problems?
>
> It was introduced by Pawel Moll in fba14ae8e924 ("ledtrig-cpu: Handle
> CPU hot(un)plugging"). It does not introduce any problems but those
> bring up / bring down levels are usually used by the core code. This
> does not look like it needs to be done _that_ early or late during the
> removal / addition of a CPU to the system.
>
> Which means this looks like it could be moved to CPU_ONLINE /
> CPU_DOWN_PREPARE which in turns means we could use dynamic IDs instead
> of those hardcoded ones since the LED subsystem does not depend on other
> components.

From the LED subsystem perspective I don't see any particular reason
for which it couldn't be accomplished from the ONLINE callbacks.

--
Best regards,
Jacek Anaszewski