FreeBSD lock order reversal (LOR) #241

lock order reversal:
 1st 0xc3cd900c ieee80211com (802.11 com lock) @ sys/net80211/ieee80211_scan.c:524
 2nd 0xc3cda41c ral0 (network driver) @ sys/dev/ral/rt2560.c:2006
		
KDB: stack backtrace:
db_trace_self_wrapper(c08867d1,e4119914,c060505a,c0888c56,c3cda41c,...) at db_trace_self_wrapper+0x26
kdb_backtrace(c0888c56,c3cda41c,c3cd80c0,c086c50c,c08707e8,...) at kdb_backtrace+0x29
witness_checkorder(c3cda41c,9,c08707e8,7d6,c0604871,...) at witness_checkorder+0x6b7
_mtx_lock_flags(c3cda41c,0,c08707e8,7d6,c0894568,...) at _mtx_lock_flags+0xb0
rt2560_start(c3cd7c00,c3cd9004,e4119a10,c068dfb2,c3cd7c00,...) at rt2560_start+0x3e
if_start(c3cd7c00,0,c0894568,184,e41199f4,...) at if_start+0x4f
ieee80211_send_nulldata(c40e7000,38,c0888342,6ce,c3cd900c) at ieee80211_send_nulldata+0x1ea
ieee80211_sta_pwrsave(c3cd9004,1,20c,6400,c3bfe000,...) at ieee80211_sta_pwrsave+0x1fe
scan_restart(c3bfe000,c3cd9004,c0895099,20c,2,...) at scan_restart+0x89
ieee80211_bg_scan(c3cd9004,c3d10818,8,1,c092b858,...) at ieee80211_bg_scan+0x113
ieee80211_recv_mgmt(c3cd9004,c3ce3400,c40e7000,80,32,...) at ieee80211_recv_mgmt+0xd9c
ieee80211_input(c3cd9004,c3ce3400,c40e7000,32,ffffffa1,...) at ieee80211_input+0x141d
rt2560_intr(c3cd9000,0,c088062e,471,c3af32e4,...) at rt2560_intr+0x824
ithread_loop(c3bf0940,e4119d38,c08803bd,305,c3bdaab0,...) at ithread_loop+0x1a4
fork_exit(c05b4780,c3bf0940,e4119d38) at fork_exit+0xb8
fork_trampoline() at fork_trampoline+0x8
--- trap 0, eip = 0, esp = 0xe4119d70, ebp = 0 ---
		

• freebsd-current (thread)
• PR kern/122033
• freebsd-net (thread)