Commit e2525a95 authored by Michał Mirosław's avatar Michał Mirosław Committed by Greg Kroah-Hartman
Browse files

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: stable@vger.kernel.org
Fixes: 9bca45f3 ("staging: wfx: allow to send 802.11 frames")
Signed-off-by: default avatarMichał Mirosław <mirq-linux@rere.qmqm.pl>
Link: https://lore.kernel.org/r/5e30397af95854b4a7deea073b730c00229f42ba.1581416843.git.mirq-linux@rere.qmqm.pl


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4033714d

drivers/staging/wfx/queue.c

+8 −8
Original line number Diff line number Diff line
@@ -130,12 +130,12 @@ static void wfx_tx_queue_clear(struct wfx_dev *wdev, struct wfx_queue *queue, 
	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);

}
@@ -207,9 +207,9 @@ void wfx_tx_queue_put(struct wfx_dev *wdev, struct wfx_queue *queue, 


	++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);

}
@@ -237,11 +237,11 @@ static struct sk_buff *wfx_tx_queue_get(struct wfx_dev *wdev, 
		__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)
@@ -259,10 +259,10 @@ int wfx_pending_requeue(struct wfx_dev *wdev, struct sk_buff *skb) 
	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;

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