Am Mittwoch, 31. Januar 2007 16:54 schrieb Alan Stern:
> On Wed, 31 Jan 2007, Pavel Machek wrote:
> > "cease IO"? No, I believe it is enough not to start new I/O. Userspace
> > is frozen at that point, it can't ask you to do I/O.
>
> There may be I/O requests sitting in a queue, already submitted by
> userspace. The suspend method should wait for existing I/O to complete
> and stop processing new entries from the queue.
As far as I understand it now, a frozen process will be in the refrigerator.
Thus it cannot be blocking somewhere else in kernel space. Yet we cannot
be sure there's no queued IO, as theres aio.
> > > On resume():
> > >
> > > 1. Don't worry about TASK_UNINTERRUPTIBLE
> > > 2. Do not restart IO that may call wake_up_interruptible()
> > >
> > > When do we restart such IO?
> >
> > We reuse signal handling code to do that for us. It is same situation
> > as when someone signals task doing I/O.
>
> Again you misunderstood the question. The driver must start queued I/O
> when its resume() method is called. It should then be okay for the driver
> to call wake_up_interruptible(), even before tasks are unfrozen.
Isn't there some code in usbfs that'll do homegrown aio and deliver a
signal to a process if io is completed?
Regards
Oliver
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