[PATCH v2 2/6] staging: wfx: annotate nested gc_list vs tx queue locking

[Michał Mirosław]

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: sta...@vger.kernel.org
Fixes: 9bca45f3d692 ("staging: wfx: allow to send 802.11 frames")
Signed-off-by: Michał Mirosław <mirq-li...@rere.qmqm.pl>
---
 drivers/staging/wfx/queue.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/wfx/queue.c b/drivers/staging/wfx/queue.c
index 0bcc61feee1d..51d6c55ae91f 100644
--- a/drivers/staging/wfx/queue.c
+++ b/drivers/staging/wfx/queue.c
@@ -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;
-- 
2.20.1

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