On Tuesday 11 February 2020 09:46:55 CET Michał Mirosław wrote:
> 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@xxxxxxxxxxxxxxx
> Signed-off-by: Michał Mirosław <mirq-linux@xxxxxxxxxxxx>
> ---
> 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
>
Reviewed-by: Jérôme Pouiller <jerome.pouiller@xxxxxxxxxx>
--
Jérôme Pouiller
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