staging: wfx: annotate nested gc_list vs tx queue locking

Lockdep is complaining about recursive locking, because it can't make
a difference between locked skb_queues. Annotate nested locks and avoid
double bh_disable/enable.

[...]
insmod/815 is trying to acquire lock:
cb7d6418 (&(&list->lock)->rlock){+...}, at: wfx_tx_queues_clear+0xfc/0x198 [wfx]

but task is already holding lock:
cb7d61f4 (&(&list->lock)->rlock){+...}, at: wfx_tx_queues_clear+0xa0/0x198 [wfx]

[...]
Possible unsafe locking scenario:

CPU0
----
lock(&(&list->lock)->rlock);
lock(&(&list->lock)->rlock);

Cc: [e-mail]
Fixes: 9bca45f3d692 ("staging: wfx: allow to send 802.11 frames")
Signed-off-by: Michał Mirosław <[e-mail]>
Link: https://lore.kernel.org/r/5e[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/wfx/queue.c

···
 	spin_lock_bh(&queue->queue.lock);
 	while ((item = __skb_dequeue(&queue->queue)) != NULL)
 		skb_queue_head(gc_list, item);
-	spin_lock_bh(&stats->pending.lock);
+	spin_lock_nested(&stats->pending.lock, 1);
 	for (i = 0; i < ARRAY_SIZE(stats->link_map_cache); ++i) {
 		stats->link_map_cache[i] -= queue->link_map_cache[i];
 		queue->link_map_cache[i] = 0;
 	}
-	spin_unlock_bh(&stats->pending.lock);
+	spin_unlock(&stats->pending.lock);
 	spin_unlock_bh(&queue->queue.lock);
 }
 
···
 
 	++queue->link_map_cache[tx_priv->link_id];
 
-	spin_lock_bh(&stats->pending.lock);
+	spin_lock_nested(&stats->pending.lock, 1);
 	++stats->link_map_cache[tx_priv->link_id];
-	spin_unlock_bh(&stats->pending.lock);
+	spin_unlock(&stats->pending.lock);
 	spin_unlock_bh(&queue->queue.lock);
 }
 
···
 		__skb_unlink(skb, &queue->queue);
 		--queue->link_map_cache[tx_priv->link_id];
 
-		spin_lock_bh(&stats->pending.lock);
+		spin_lock_nested(&stats->pending.lock, 1);
 		__skb_queue_tail(&stats->pending, skb);
 		if (!--stats->link_map_cache[tx_priv->link_id])
 			wakeup_stats = true;
-		spin_unlock_bh(&stats->pending.lock);
+		spin_unlock(&stats->pending.lock);
 	}
 	spin_unlock_bh(&queue->queue.lock);
 	if (wakeup_stats)
···
 	spin_lock_bh(&queue->queue.lock);
 	++queue->link_map_cache[tx_priv->link_id];
 
-	spin_lock_bh(&stats->pending.lock);
+	spin_lock_nested(&stats->pending.lock, 1);
 	++stats->link_map_cache[tx_priv->link_id];
 	__skb_unlink(skb, &stats->pending);
-	spin_unlock_bh(&stats->pending.lock);
+	spin_unlock(&stats->pending.lock);
 	__skb_queue_tail(&queue->queue, skb);
 	spin_unlock_bh(&queue->queue.lock);
 	return 0;