Re: broken suspend [Was: 2.6.24-rc2-mm1]

[Rudolf Marek <r.marek@assembler.cz>]

Hello all,
> > > gives coretemp_cpu_callback -> coretemp_device_remove ->
> > > platform_device_unregister, so coretemp seems to be what I have and you don't.
>
> Yes.
>
> For the coretemp developers: coretemp_cpu_callback() needs to be more 
> careful about what it does.  During a system sleep transition (suspend, 
> hibernate, resume) it isn't possible to register or unregister a 
> device.  Attempts to register will fail and attempts to unregister will 
> block until the system sleep is over -- and for this callback that 
> means hanging.

Well I wrote the driver. Thanks for the clarification. If I recall correctly I 
looked how this part should be done from others drivers. Now while checking
what happened to the file, seems Rafael added something related.

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=8bb7844286fb8c9fce6f65d8288aeb09d03a5e0d

> It's not clear what the best way is to fix this.  Perhaps the CPU 
> notification should be sent along with a special flag indicating that 
> the CPU transition is part of a system sleep (although this seems 
> racy).  Perhaps the driver should notice when a system sleep begins, 
> and defer all CPU-change handling until after the sleep is over.

maybe it does exist?  CPU_DOWN_PREPARE ?

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=Documentation/cpu-hotplug.txt;hb=HEAD

Unfortunately I'm not very familiar with this, calling the 
coretemp_device_remove from CPU_DOWN_PREPARE would help? Looking at microcode 
driver, seems it just hide sysfs interface from user.

Thanks,
Rudolf
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