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Subject[PATCH 5.6 16/23] staging: wfx: annotate nested gc_list vs tx queue locking
Date
From: Michał Mirosław <mirq-linux@rere.qmqm.pl>

commit e2525a95cc0887c7dc0549cb5d0ac3e796e1d54c upstream.

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: 9bca45f3d692 ("staging: wfx: allow to send 802.11 frames")
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Link: https://lore.kernel.org/r/5e30397af95854b4a7deea073b730c00229f42ba.1581416843.git.mirq-linux@rere.qmqm.pl
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/staging/wfx/queue.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

--- a/drivers/staging/wfx/queue.c
+++ b/drivers/staging/wfx/queue.c
@@ -130,12 +130,12 @@ static void wfx_tx_queue_clear(struct wf
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 *wd

++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(
__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 *
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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