Re: 2.6.23-rc1: USB hard disk broken

On Sunday 05 August 2007, David Brownell wrote:

> > > 2007-08-05_10:30:27.75572 kern.err:
> > > 		ehci_hcd 0000:00:1d.7: dev 6 ep1in scatterlist error 0/-121
> 
> That's rather strange since it means a *success* (urb->status 0) was
> reported after a short read (scatterlist status -120, -EREMOTEIO).

I'm baffled by that also.  It should never happen.

> The hardware should have stopped queue processing after the short
> read, because of how qtd->hw_alt_next gets set up ... at least,
> that's how I remember it, these many years after writing that code.
> 
> It might be that because of the issue noted below, it was wrongly
> restarted by the software.
> 
> 
> > > 2007-08-05_10:30:27.86576 kern.info: usb 1-6: reset high speed USB device using \
> > > ehci_hcd and address 5 2007-08-05_10:30:55.95293 kern.info: usb 1-6: USB \
> > > disconnect, address 5 2007-08-05_10:30:55.95300 kern.err:
> > > 		ehci_hcd 0000:00:1d.7: dev 6 ep1in scatterlist error -108/-108 
> 
> That one just means nobody updated that test to recognize that
> the -ESHUTDOWN (-108) triggered after disconnect is a "clean"
> failure like the ones triggered by unlinking.
> 
> However it also indicates that something changed in the unlink
> code paths, since I see the *expected* code (-ECONNRESET) is no
> longer being set by usbcore during unlinks ...

What do you mean?  Normal async unlinks still use that error value.  
Look at the usb_unlink_urb() routine in core/urb.c.

>  it's not quite
> clear to me what else that change will have broken.  Including
> whether that might not explain how the hardware queue got wrongly
> restarted after the short read above.

Could there have been a change in the unlink or completion code in 
ehci-hcd?

Alan Stern


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