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From: Oliver Neukum <oliver@neukum.name>
To: "John Tyner" <jtyner@cs.ucr.edu>, "Greg KH" <greg@kroah.com>
Subject: Re: Vicam/3com homeconnect usb camera driver
Date: Sun, 6 Oct 2002 23:44:02 +0200
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On Sunday 06 October 2002 23:32, John Tyner wrote:
> > And you should probably kill the tasklet before you unregister the video
> > device.
>
> The more I think about this, the more I think that killing the tasklet
> after unregistering the device is the correct way.
>
> From what I can tell, there are two ways that the disconnect function can
> be called: a physical disconnect or a module removal.

And as a result of an ioctl() through usbfs.

> In the case of a physical disconnect, the ordering probably doesn't matter
> because the tasklet won't be scheduled again because urb's would fail to
> complete successfully.
>
> The case of module removal becomes a bit more complicated (for reasons
> concerning module unload races that are being discussed by people far
> smarter than I). But in any event, I think that it makes more sense to
> unregister the open/close/etc. interface so that there is less chance of
> trying to send another urb (thus causing another schedule of the tasklet)
> before actually killing the tasklet.
>
> This also brings up the (somewhat) rhetorical question I posed in the
> driver's disconnect function. What happens when a disconnect occurs while
> the device is open?

I can't tell right now. I'll sync up after returning home and look into the 
matter.

	Regards
		Oliver
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