Re: [PATCH 4/5] usb_serial: Kill port mutex

[Oliver Neukum]

Am Mittwoch, 7. Oktober 2009 23:34:12 schrieb Alan Stern:
> I'm losing track of the original point of this thread.  IIRC, the
> problem is how the resume method should know whether or not to submit
> the receive URB(s).  It can't afford to acquire the port mutex because
> it might be called by open or close, at which time the mutex is already
> held.
>
> 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?
2. Can we get by with only one flag?

	Regards
		Oliver


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