ath9k: Fix locking issue during tx completion

The received tx status of aggregated frame without BlockAck may
cause deaf state in AR5416 cards. So the driver does a reset to
recover. When this happens, we release the pcu_lock before doing
a reset as ath_rest acquires pcu_lock. This is ugly and also not
atomic. Fixing this addresses the TX DMA failure also.

ath_tx_complete_aggr can be called from different paths which
takes different variants of spin_lock. This patch also addresses
the following warning.

WARNING: at kernel/timer.c:1011 del_timer_sync+0x4e/0x50()
Call Trace:
 <IRQ>  [<ffffffff8104be3a>] warn_slowpath_common+0x7a/0xb0
 [<ffffffff8104be85>] warn_slowpath_null+0x15/0x20
 [<ffffffff8105915e>] del_timer_sync+0x4e/0x50
 [<ffffffffa03726be>] ath_reset+0x3e/0x210 [ath9k]
 [<ffffffff8135cdaf>] ? _raw_spin_unlock_bh+0x1f/0x30
 [<ffffffffa037760a>] ath_tx_complete_aggr.isra.26+0x54a/0xa40 [ath9k]

Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/beacon.c

@@ -385,7 +385,9 @@ void ath_beacon_tasklet(unsigned long data)
 			ath_dbg(common, ATH_DBG_BSTUCK,
 				"beacon is officially stuck\n");
 			sc->sc_flags |= SC_OP_TSF_RESET;
+			spin_lock(&sc->sc_pcu_lock);
 			ath_reset(sc, true);
+			spin_unlock(&sc->sc_pcu_lock);
 		}
 
 		return;