Re: [PATCH V2 1/2] usb: gadget/uvc: Port UVC webcam gadget to use videobuf2 framework

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On Thu, 9 Aug 2012, Laurent Pinchart wrote:

> Hi Alan,
> 
> On Wednesday 08 August 2012 21:31:12 Alan Stern wrote:
> > On Wed, 8 Aug 2012, Laurent Pinchart wrote:
> > > I guess it depends on the usb_ep_dequeue() API. The function documentation
> > > doesn't clearly state whether calling it with an already dequeuing request
> > > is valid (in which case it should return an error, possibly print a debug
> > > message, but not a warning/error message) or not (in which case it can be
> > > very vocal about it, and even WARN_ON()).
> > 
> > It is valid.  It pretty much has to be, because we need to handle the
> > possibility that two threads might try to cancel the same request at
> > the same time.
> 
> In that case we should fix the UDC drivers to be less vocal when 
> usb_ep_dequeue() is called for a non-queued request. Bhupesh, would you like 
> to send patches for that ?

That's right.  Trying to dequeue a non-queued request should return 
-EINVAL or something similar, but it shouldn't produce any log 
messages.

Alan Stern

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