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

From: Sebastian Andrzej Siewior
Date: Fri Jul 15 2016 - 10:11:25 EST

* 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