unplugging a umass-device panics 4.x

[Mikhail Teterin]

Hello!

This happened 4 times today on the same machine:

17:59:12 : umass0: at uhub2 port 1 (addr 4) disconnected
17:59:12 : (da0:umass-sim0:0:0:0): lost device
17:59:12 : (da0:umass-sim0:0:0:0): removing device entry
17:59:12 : umass0: detached
17:59:12 : 
17:59:12 : 
17:59:12 : Fatal trap 12: page fault while in kernel mode
17:59:12 : fault virtual address  = 0x3c
17:59:12 : fault code             = supervisor read, page not present
17:59:12 : instruction pointer    = 0x8:0xc01b3732
17:59:12 : stack pointer          = 0x10:0xd7ad3f08
17:59:12 : frame pointer          = 0x10:0xd7ad3f08
17:59:12 : code segment           = base 0x0, limit 0xfffff, type 0x1b
17:59:12 : = DPL 0, pres 1, def32 1, gran 1
17:59:12 : processor eflags       = interrupt enabled, resume, IOPL = 0
17:59:12 : current process                = 5 (usb1)
17:59:12 : interrupt mask         = none
17:59:12 : trap number            = 12
17:59:12 : panic: page fault

Tha machine runs FreeBSD 4.11-STABLE #4: from Sat May 7... The device
is:

umass0: SanDisk Corporation ImageMate CompactFlash USB, rev 1.10/0.09, addr 4

According to `nm /kernel', the symbols near the instruction pointer above
are:

	c01b36e8 T device_set_softc
	c01b372c T device_get_ivars
	c01b373c T device_set_ivars
	c01b3750 T device_get_state

Any suggestions/patches for usb? Thanks!

	-mi