usb/115298: Turning off USB printer panics kernel

[Jonathan Hanna]

>Number:         115298
>Category:       usb
>Synopsis:       Turning off USB printer panics kernel
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    freebsd-usb
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Aug 08 08:20:01 GMT 2007
>Closed-Date:
>Last-Modified:
>Originator:     Jonathan Hanna
>Release:        FreeBSD 7.0-CURRENT i386
>Organization:
>Environment:
System: FreeBSD gbh.pangolin-systems.com 7.0-CURRENT FreeBSD 7.0-CURRENT #16: Wed Aug 1 18:50:29 PDT 2007 jhanna at gbh.pangolin-systems.com:/usr/obj/usr/src/sys/GBH i386

>Description:

When a USB printer was turned off, perhaps while lpd was printing
to it, the kernel paniced with:

ulpt0: at uhub1 port 7 (addr 6) disconnected
ulpt0: detached
panic: Bad tailq NEXT(0xd5924db8->tqh_last) != NULL
cpuid = 0
KDB: enter: panic
[thread pid 13 tid 100001 ]
Stopped at      kdb_enter+0x32: leave
db> bt
Tracing pid 13 tid 100001 td 0xc5915e00
kdb_enter(c0a910d8,0,c0a47d72,e016fc48,0,..) at kdb_enter+0x32
panic(c0a47d72,d5924db8,c0a92274,1ac,c5908c00,...) at panic+0x124
callout_reset(c0b78f28,a,c0558f70,c5908c00,...) at callout_reset+0x169
dcons_timeout(c5908c00,0,c0a92274,f8,0,...) at dcons_timeout+0x81
softcock(0,0,c0a8dd07,471,c59543e4,...) at softclock+0x299
ithread_loop(c5913400,e016fd38,c0a8da7b,315,c59142ac,...) at ithread_loop+0x1b5
fork_exit(c072f5d0,c5913400,e016fd38) at fork_exit+0xb8
fork_trampoline() at fork_trampoline+0x8
--- trap 0, eip = 0, esp = 0xe016fd70, ebp = 0 ---
db>

>How-To-Repeat:
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted: