Re: [RFC] usb: remove "clear_halt for a busy endpoint" warning

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On Fri, Feb 14, 2014 at 10:31:20AM -0500, Alan Stern wrote:
> On Fri, 14 Feb 2014, Stanislaw Gruszka wrote:
> 
> > On Thu, Feb 13, 2014 at 11:45:16AM -0500, Alan Stern wrote:
> > > @@ -1074,6 +1089,7 @@ static int proc_clearhalt(struct dev_sta
> > >  	ret = checkintf(ps, ret);
> > >  	if (ret)
> > >  		return ret;
> > > +	check_reset_of_active_ep(ps->dev, ep, "CLEAR_HALT");
> > >  	if (ep & USB_DIR_IN)
> > >  		pipe = usb_rcvbulkpipe(ps->dev, ep & 0x7f);
> > >  	else
> > 
> > In documentation is written:
> 
> What documentation?  Where?  Maybe the documentation should be updated.

Documentation/DocBook/usb.tmpl

> > Is possible that user space driver can issue dozen of URBs , then get
> > -EPIPE for last of them, and then call CLEAR_HALT ?
> 
> Certainly that is possible.  It wouldn't trigger the warning, because
> after the last URB terminates with -EPIPE there won't be any more URBs
> in the queue.
> 
> > According
> > documentation, this behaviour should be correct.
> 
> And indeed, it is correct.
> 
> What would be incorrect is if userspace issues dozens of URBs, gets
> -EPIPE for the third URB, and then does CLEAR_HALT without first
> cancelling all the remaining URBs.

Now I know what to tell user space maintainers. Thank you!

Stanislaw
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