panic w/ USB<->serial adapter and modem

[M. Warner Losh]

In message: <200412190252.iBJ2q1eW002380 at wattres.watt.com>
            steve at Watt.COM (Steve Watt) writes:
: So it's pretty clear, reading that over, that uhci_abort_xfer
: *IS* being called from interrupt context, namely when carrier
: drops.  There's some kind of think-o happening in there, but
: I'm not sure quite what to do about it.
: 
: It also looks like there's some risk of ugly recursion, because
: usb_transfer_complete is called from uhci_abort_xfer, but I really
: haven't analyzed the code path well enough to be certain that
: it's OK.

Hmmm, that's generally not supposed to be possible, but with FreeBSD's
stack it is.  I have changes to queue everything to a taskqueue.
Maybe those would help...

Warner