net: caif: avoid using qdisc_qlen()

Such helper does not cope correctly with NOLOCK qdiscs.
In the following patches we will move back qlen to per CPU
values for such qdiscs, so qdisc_qlen_sum() is not an option,
too.
Instead, use qlen only for lock qdiscs, and always set
flow off for NOLOCK qdiscs with a not empty tx queue.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 4 deletions

diff --git a/net/caif/caif_dev.c b/net/caif/caif_dev.c
index 711d7156efd8..6c6e01963aac 100644
--- a/net/caif/caif_dev.c
+++ b/net/caif/caif_dev.c
@@ -186,15 +186,19 @@ static int transmit(struct cflayer *layer, struct cfpkt *pkt)
                 goto noxoff;
 
         if (likely(!netif_queue_stopped(caifd->netdev))) {
+                struct Qdisc *sch;
+
                 /* If we run with a TX queue, check if the queue is too long*/
                 txq = netdev_get_tx_queue(skb->dev, 0);
-                qlen = qdisc_qlen(rcu_dereference_bh(txq->qdisc));
-
-                if (likely(qlen == 0))
+                sch = rcu_dereference_bh(txq->qdisc);
+                if (likely(qdisc_is_empty(sch)))
                         goto noxoff;
 
+                /* can check for explicit qdisc len value only !NOLOCK,
+                 * always set flow off otherwise
+                 */
                 high = (caifd->netdev->tx_queue_len * q_high) / 100;
-                if (likely(qlen < high))
+                if (!(sch->flags & TCQ_F_NOLOCK) && likely(sch->q.qlen < high))
                         goto noxoff;
         }