Since txq->axq_lock may be hold in softirq context, it must be
acquired with spin_lock_bh() instead of spin_lock() if softieq is
enabled.

The patch fixes the lockdep warning below when unloading ath9k modules.

=================================
[ INFO: inconsistent lock state ]
2.6.33-wl #12
---------------------------------
inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
rmmod/3642 [HC0[0]:SC0[0]:HE1:SE1] takes:
 (&(&txq->axq_lock)->rlock){+.?...}, at: [<ffffffffa03568c3>] ath_tx_node_cleanup+0x62/0x180 [ath9k]
{IN-SOFTIRQ-W} state was registered at:
  [<ffffffff8107577d>] __lock_acquire+0x2f6/0xd35
  [<ffffffff81076289>] lock_acquire+0xcd/0xf1
  [<ffffffff813a7486>] _raw_spin_lock_bh+0x3b/0x6e
  [<ffffffffa0356b49>] spin_lock_bh+0xe/0x10 [ath9k]
  [<ffffffffa0358ec7>] ath_tx_tasklet+0xcd/0x391 [ath9k]
  [<ffffffffa0354f5f>] ath9k_tasklet+0x70/0xc8 [ath9k]
  [<ffffffff8104e601>] tasklet_action+0x8c/0xf4
  [<ffffffff8104f459>] __do_softirq+0xf8/0x1cd
  [<ffffffff8100ab1c>] call_softirq+0x1c/0x30
  [<ffffffff8100c2cf>] do_softirq+0x4b/0xa3
  [<ffffffff8104f045>] irq_exit+0x4a/0x8c
  [<ffffffff813acccc>] do_IRQ+0xac/0xc3
  [<ffffffff813a7d53>] ret_from_intr+0x0/0x16
  [<ffffffff81302d52>] cpuidle_idle_call+0x9e/0xf8
  [<ffffffff81008be7>] cpu_idle+0x62/0x9d
  [<ffffffff81391c1a>] rest_init+0x7e/0x80
  [<ffffffff818bbd38>] start_kernel+0x3e8/0x3f3
  [<ffffffff818bb2bc>] x86_64_start_reservations+0xa7/0xab
  [<ffffffff818bb3b8>] x86_64_start_kernel+0xf8/0x107
irq event stamp: 42037
hardirqs last  enabled at (42037): [<ffffffff813a7b21>] _raw_spin_unlock_irqrestore+0x47/0x56
hardirqs last disabled at (42036): [<ffffffff813a72f4>] _raw_spin_lock_irqsave+0x2b/0x88
softirqs last  enabled at (42000): [<ffffffffa0353ea6>] spin_unlock_bh+0xe/0x10 [ath9k]
softirqs last disabled at (41998): [<ffffffff813a7463>] _raw_spin_lock_bh+0x18/0x6e

other info that might help us debug this:
4 locks held by rmmod/3642:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff8132c10d>] rtnl_lock+0x17/0x19
 #1:  (&wdev->mtx){+.+.+.}, at: [<ffffffffa01e53f2>] cfg80211_netdev_notifier_call+0x28d/0x46d [cfg80211]
 #2:  (&ifmgd->mtx){+.+.+.}, at: [<ffffffffa0260834>] ieee80211_mgd_deauth+0x3f/0x17e [mac80211]
 #3:  (&local->sta_mtx){+.+.+.}, at: [<ffffffffa025a381>] sta_info_destroy_addr+0x2b/0x5e [mac80211]

stack backtrace:
Pid: 3642, comm: rmmod Not tainted 2.6.33-wl #12
Call Trace:
 [<ffffffff81074469>] valid_state+0x178/0x18b
 [<ffffffff81014f94>] ? save_stack_trace+0x2f/0x4c
 [<ffffffff81074e08>] ? check_usage_backwards+0x0/0x88
 [<ffffffff8107458f>] mark_lock+0x113/0x230
 [<ffffffff810757f1>] __lock_acquire+0x36a/0xd35
 [<ffffffff8101018d>] ? native_sched_clock+0x2d/0x5f
 [<ffffffffa03568c3>] ? ath_tx_node_cleanup+0x62/0x180 [ath9k]
 [<ffffffff81076289>] lock_acquire+0xcd/0xf1
 [<ffffffffa03568c3>] ? ath_tx_node_cleanup+0x62/0x180 [ath9k]
 [<ffffffff810732eb>] ? trace_hardirqs_off+0xd/0xf
 [<ffffffff813a7193>] _raw_spin_lock+0x36/0x69
 [<ffffffffa03568c3>] ? ath_tx_node_cleanup+0x62/0x180 [ath9k]
 [<ffffffffa03568c3>] ath_tx_node_cleanup+0x62/0x180 [ath9k]
 [<ffffffff810749ed>] ? trace_hardirqs_on+0xd/0xf
 [<ffffffffa0353950>] ath9k_sta_remove+0x22/0x26 [ath9k]
 [<ffffffffa025a08f>] __sta_info_destroy+0x1ad/0x38c [mac80211]
 [<ffffffffa025a394>] sta_info_destroy_addr+0x3e/0x5e [mac80211]
 [<ffffffffa02605d6>] ieee80211_set_disassoc+0x175/0x180 [mac80211]
 [<ffffffffa026084d>] ieee80211_mgd_deauth+0x58/0x17e [mac80211]
 [<ffffffff813a60c1>] ? __mutex_lock_common+0x37f/0x3a4
 [<ffffffffa01e53f2>] ? cfg80211_netdev_notifier_call+0x28d/0x46d [cfg80211]
 [<ffffffffa026786e>] ieee80211_deauth+0x1e/0x20 [mac80211]
 [<ffffffffa01f47f9>] __cfg80211_mlme_deauth+0x130/0x13f [cfg80211]
 [<ffffffffa01e53f2>] ? cfg80211_netdev_notifier_call+0x28d/0x46d [cfg80211]
 [<ffffffff810732eb>] ? trace_hardirqs_off+0xd/0xf
 [<ffffffffa01f7eee>] __cfg80211_disconnect+0x111/0x189 [cfg80211]
 [<ffffffffa01e5433>] cfg80211_netdev_notifier_call+0x2ce/0x46d [cfg80211]
 [<ffffffff813aa9ea>] notifier_call_chain+0x37/0x63
 [<ffffffff81068c98>] raw_notifier_call_chain+0x14/0x16
 [<ffffffff81322e97>] call_netdevice_notifiers+0x1b/0x1d
 [<ffffffff8132386d>] dev_close+0x6a/0xa6
 [<ffffffff8132395f>] rollback_registered_many+0xb6/0x2f4
 [<ffffffff81323bb8>] unregister_netdevice_many+0x1b/0x66
 [<ffffffffa026494f>] ieee80211_remove_interfaces+0xc5/0xd0 [mac80211]
 [<ffffffffa02580a2>] ieee80211_unregister_hw+0x47/0xe8 [mac80211]
 [<ffffffffa035290e>] ath9k_deinit_device+0x7a/0x9b [ath9k]
 [<ffffffffa035bc26>] ath_pci_remove+0x38/0x76 [ath9k]
 [<ffffffff8120940a>] pci_device_remove+0x2d/0x51
 [<ffffffff8129d797>] __device_release_driver+0x7b/0xd1
 [<ffffffff8129d885>] driver_detach+0x98/0xbe
 [<ffffffff8129ca7a>] bus_remove_driver+0x94/0xb7
 [<ffffffff8129ddd6>] driver_unregister+0x6c/0x74
 [<ffffffff812096d2>] pci_unregister_driver+0x46/0xad
 [<ffffffffa035bae1>] ath_pci_exit+0x15/0x17 [ath9k]
 [<ffffffffa035e1a2>] ath9k_exit+0xe/0x2f [ath9k]
 [<ffffffff8108050a>] sys_delete_module+0x1c7/0x236
 [<ffffffff813a7df5>] ? retint_swapgs+0x13/0x1b
 [<ffffffff810749b5>] ? trace_hardirqs_on_caller+0x119/0x144
 [<ffffffff8109b9f6>] ? audit_syscall_entry+0x11e/0x14a
 [<ffffffff81009bb2>] system_call_fastpath+0x16/0x1b
wlan1: deauthenticating from 00:23:cd:e1:f9:b2 by local choice (reason=3)
PM: Removing info for No Bus:wlan1
cfg80211: Calling CRDA to update world regulatory domain
PM: Removing info for No Bus:rfkill2
PM: Removing info for No Bus:phy1
ath9k 0000:16:00.0: PCI INT A disabled
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>