On Thu, 8 Oct 2009, Oliver Neukum wrote:
> Am Donnerstag, 8. Oktober 2009 16:58:39 schrieb Alan Stern:
> > On Thu, 8 Oct 2009, Oliver Neukum wrote:
> > > Am Mittwoch, 7. Oktober 2009 23:34:12 schrieb Alan Stern:
>
> > > > Other schemes could work, but to me it seems simplest to rely on a flag
> > > > protected by a spinlock. The flag would mean "URBs are supposed to be
> > > > queued unless we are suspended". It would be set by open and
> > > > unthrottle, and cleared by close and throttle.
> > >
> > > 1. Why a spinlock?
> >
> > Because the amount of work involved seems too small for a mutex. But
> > you could use a mutex if you wanted, since everything occurs in process
> > context.
>
> We have to submit URBs under that lock.
Yes. What's your point?
> > > 2. Can we get by with only one flag?
> >
> > If all you want to do is answer a single question ("Should URBs be
> > submitted") then a single flag should be all you need. Why, do you
> > think more information will be necessary? You can always add more.
>
> We have at least three reasons URBs should not be submitted.
> - closure
> - throttling
> - suspension
> Resume() should not submit if either closure or throttling are active,
> neither should unthrottle() resubmit if closure or suspension are active.
True. Nor should open() submit if throttling is active. Feel free to
use three separate flags. :-)
Alan Stern
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