Re: [suspend/resume] Re: userspace notification from module

[Daniel Borkmann]

Rafael J. Wysocki wrote:
> On Monday 04 January 2010, BartÅomiej ZimoÅ wrote:
>> And what do You think about sending extra signals to processes?
> 
> I don't see a problem with this in principle, although I don't think signals
> are very suitable for this particular purpose, because you need two-way
> communication between the power manager and the processes it's going to
> notify (because it has to wait for the processes to finish their preparations
> and to tell it that they are ready).

Again, just to abandon some thoughts... do you really need that "two-way
communication"? I mean if the kernel delivers that specific signal to
the process/task_struct [do_signal():handle_signal()] it has to save the
original execution context that will later on be restored after the
non-default signal handling function returns. This is our ACK /
notification for the successful return of the programs "suspend
handler". The kernel module (if such exists) could be notified about
that for instance by a simple notifier hook within kernelspace. I mean
if I see this right, the "two-way" is just for the ACK isn't it?

Best regards,
Daniel

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