OHCI hangs after failing to free resources

Sometimes upon removing one of our devices (for which we have a custom USB driver), OHCI fails to free all the associated resources with the device. The problem is always associated with the "IRQ INTR_SF lossage" message, which I assume is probably a hardware issue (we are using the ZFMicro USB chipset, which has given us other headaches).

Anyways, I realized that our disconnect() method was never getting called in these cases, and it's because there is a lockup in usb_hcd_endpoint_disable.  Our device has two endpoints (plus control) - one for reads, and one for writes.  When we hit this condition, it always hangs while disabling the read endpoint. I added a few lines of debug code to ohci-hcd.c and hcd.c to try to figure out what's going on, and traced it to the usb_kill_urb on line 1386 of hcd.c.

Apr 27 18:50:43 blademan26 user.info kernel: usb 1-2.2: USB disconnect, address 18
Apr 27 18:50:43 blademan26 user.debug kernel: usb 1-2.2: unregistering device
Apr 27 18:50:43 blademan26 user.debug kernel: usb 1-2.2: usb_disable_device nuking all URBs
Apr 27 18:50:43 blademan26 user.debug kernel: ohci_hcd 0000:00:13.0: shutdown urb c2aac180 pipe 40411280 ep2in-intr
Apr 27 18:50:47 blademan26 user.warn kernel: ohci_hcd 0000:00:13.0: IRQ INTR_SF lossage
Apr 27 18:50:47 blademan26 user.err kernel: ohci_hcd 0000:00:13.0: leak ed c3c5f500 (#82) state 0 (has tds)
Apr 27 18:50:47 blademan26 user.err kernel: ohci_hcd 0000:00:13.0: free td c3e47640
Apr 27 18:50:47 blademan26 user.err kernel: ohci_hcd 0000:00:13.0: freed
Apr 27 18:50:47 blademan26 user.debug kernel: ohci_hcd 0000:00:13.0: urb list not empty <just after line 1373>
Apr 27 18:50:47 blademan26 user.debug kernel: ohci_hcd 0000:00:13.0: kill urb: c2aac180 status -108 <just before line 1386>

The call to usb_kill_urb never returns. What would cause that to happen? It seems like that this point, we know the device is long gone, so there should be some way to force the issue.

When this occurs the only solution I've found is to reboot, as the ohci module can't be unloaded while it's in the hung state.

Thanks,
Mike Nuss

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