if_aue panic: trying to sleep while sleeping is prohibited

I got the following panic when I tried plugging in a USB 10/100 Ethernet
adapter (aue(4) driver).  This is -CURRENT about two weeks old.

#9  0xc063f75b in panic (fmt=0xc086cd96 "trying to sleep while sleeping is prohibited")
    at /d2/emaste/head/src/sys/kern/kern_shutdown.c:550
#10 0xc065e63c in sleepq_add (wchan=0xc1d2c400, lock=0x0, wmesg=0x12 <Address 0x12 out of bounds>,
    flags=0) at /d2/emaste/head/src/sys/kern/subr_sleepqueue.c:273
#11 0xc064564d in msleep (ident=0xc1d2c400, mtx=0x0, priority=76, wmesg=0xc08601f0 "usbsyn", timo=0)
    at /d2/emaste/head/src/sys/kern/kern_synch.c:205
#12 0xc05e26d9 in usbd_transfer (xfer=0xc1d2c400) at /d2/emaste/head/src/sys/dev/usb/usbdi.c:344
#13 0xc05e26f9 in usbd_sync_transfer (xfer=0x12) at /d2/emaste/head/src/sys/dev/usb/usbdi.c:355
#14 0xc05e2eb5 in usbd_do_request_flags_pipe (dev=0xc1eda580, pipe=0x12, req=0xd44a2be8,
    data=0xd44a2c04, flags=0, actlen=0x0, timeout=5000) at /d2/emaste/head/src/sys/dev/usb/usbdi.c:978
#15 0xc05e2e54 in usbd_do_request_flags (dev=0x12, req=0xd44a2be8, data=0xd44a2c04, flags=0, actlen=0x0,
    timo=5000) at /d2/emaste/head/src/sys/dev/usb/usbdi.c:949
#16 0xc05e2e32 in usbd_do_request (dev=0xc1eda580, req=0xd44a2be8, data=0xd44a2c04)
    at /d2/emaste/head/src/sys/dev/usb/usbdi.c:941
#17 0xc05c582a in aue_csr_write_1 (sc=0xc1ebe000, reg=-1056755712, val=1)
    at /d2/emaste/head/src/sys/dev/usb/if_aue.c:327
#18 0xc05c59a1 in aue_miibus_readreg (dev=0xc1eda480, phy=1, reg=1)
    at /d2/emaste/head/src/sys/dev/usb/if_aue.c:442
#19 0xc055d69f in miibus_readreg (dev=0xc1edae80, phy=1, reg=1) at miibus_if.h:25
#20 0xc055ddaf in mii_phy_tick (sc=0xc1c2b8c0) at miibus_if.h:25
#21 0xc0563c2b in ukphy_service (sc=0xc1c2b8c0, mii=0x0, cmd=1)
    at /d2/emaste/head/src/sys/dev/mii/ukphy.c:211
#22 0xc055d99b in mii_tick (mii=0xc1c2a680) at /d2/emaste/head/src/sys/dev/mii/mii.c:363
#23 0xc05c6406 in aue_tick (xsc=0xc1ebe000) at /d2/emaste/head/src/sys/dev/usb/if_aue.c:1032
#24 0xc064c0c1 in softclock (dummy=0x0) at /d2/emaste/head/src/sys/kern/kern_timeout.c:290
#25 0xc062cda2 in ithread_execute_handlers (p=0xc19ec890, ie=0xc1a1d580)
    at /d2/emaste/head/src/sys/kern/kern_intr.c:662
#26 0xc062ced3 in ithread_loop (arg=0xc199eb00) at /d2/emaste/head/src/sys/kern/kern_intr.c:745
#27 0xc062c034 in fork_exit (callout=0xc062ce6c <ithread_loop>, arg=0xc199eb00, frame=0xd44a2d38)
    at /d2/emaste/head/src/sys/kern/kern_fork.c:789
#28 0xc07eb83c in fork_trampoline () at /d2/emaste/head/src/sys/i386/i386/exception.s:208

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Ed Maste, Sandvine Incorporated