rum(4) crash with adhoc

[Paul B Mahol]

While testing adhoc with rum and ndis I got hit with this one:

Kernel page fault with the following non-sleepable locks held:
exclusive sleep mutex rum0 (network driver) r = 0 (0xc405e1a4) locked
@ /usr/src/sys/modules/usb/usb/../../../dev/usb/usb_request.c:540
KDB: stack backtrace:
db_trace_self_wrapper(c062f6f1,e63e6a94,c04e7ddf,21c,0,...) at
db_trace_self_wrapper+0x26
kdb_backtrace(21c,0,ffffffff,c07dd8f4,e63e6acc,...) at kdb_backtrace+0x29
_witness_debugger(c0631b57,e63e6ae0,4,1,0,...) at _witness_debugger+0x1e
witness_warn(5,0,c064f703,c04e6f77,c069bba0,...) at witness_warn+0x1e9
trap(e63e6b6c) at trap+0x179
calltrap() at calltrap+0x6
--- trap 0xc, eip = 0xc451c3af, esp = 0xe63e6bac, ebp = 0xe63e6bb8 ---
ieee80211_getcapinfo(c41a8000,ffff,c450c616,c41a887c,c4566400,...) at
ieee80211_getcapinfo+0x78
ieee80211_beacon_construct(c4561000,18,676,43014,c3e5d800,...) at
ieee80211_beacon_construct+0x67
ieee80211_beacon_alloc(c4561000,c41a887c,6,2cb,e63e6c48,...) at
ieee80211_beacon_alloc+0x99
rum_newstate(c41a8000,5,ffffffff,654,e63e6ca8,...) at rum_newstate+0x2e7
ieee80211_newstate_cb(c41a8000,2,c0630f47,51,c4486418,...) at
ieee80211_newstate_cb+0xac
taskqueue_run(c4486400,c4486418,0,c0621864,0,...) at taskqueue_run+0xfd
taskqueue_thread_loop(c455a074,e63e6d38,c0627aba,343,c069bba0,...) at
taskqueue_thread_loop+0x65
fork_exit(c04e159c,c455a074,e63e6d38) at fork_exit+0xb8
fork_trampoline() at fork_trampoline+0x8
--- trap 0, eip = 0, esp = 0xe63e6d70, ebp = 0 ---

Only what I were trying to do is to set SSID for rum0 adhoc wlanmode.

Looks like it will not crash if same SSID is already available on network.