Re: [PATCH] usb: core: update wait routine to set a timeout

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On Thu, May 29, 2014 at 10:50:03AM -0400, Alan Stern wrote:
> On Thu, 29 May 2014, Huang Rui wrote:
> 
> > Currently, in usb_sg_wait routine there isn't a timeout on waiting for
> > completion signal. When using TEST 5 -> 8 at usbtest module to verify
> > a new device controller with gadget zero, it would be hang on this
> > phase and this routine waits forever.
> 
> Why did it hang?  That's the real problem; you should fix that instead 
> of adding a timeout.
> 

Right, it might be a HW issue and still under analysis.

> > So it should add a timeout about
> > 10s to export a TIMEOUT error to return.
> 
> What makes you think 10 seconds is a good timeout value?
> 

This value is rough estimate, and can be changed.

> Sorry, this is not acceptable.  Any timeout value you specify has to 
> work for _all_ places that call this routine.  10 minutes might be 
> okay.
> 

But as a developer's view, when I run the tests, it should be better
to report a error even though it fails. But in some specail error
cases, usbtest TEST 5 -> 8 which used usb_sg_wait might wait forever
and the test is unable to stop. I think it is still not expected,
right? So do you have any idea to resolve this issue to make the
usbtest report the error codes and complete normally?

Thanks,
Rui
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