pkt_sched: Add 'deactivated' state.

This new state lets dev_deactivate() mark a qdisc as having been
deactivated.

dev_queue_xmit() and ing_filter() check for this bit and do not
try to process the qdisc if the bit is set.

dev_deactivate() polls the qdisc after setting the bit, waiting
for both __QDISC_STATE_RUNNING and __QDISC_STATE_SCHED to clear.

This isn't perfect yet, but subsequent changesets will make it so.
This part is just one piece of the puzzle.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 1 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 600bb23c4c2e..d9e31f63aded 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1800,6 +1800,12 @@ gso:
 
 		spin_lock(root_lock);
 
+		if (unlikely(test_bit(__QDISC_STATE_DEACTIVATED, &q->state))) {
+			spin_unlock(root_lock);
+			rc = NET_XMIT_DROP;
+			goto out_kfree_skb;
+		}
+
 		rc = qdisc_enqueue_root(skb, q);
 		qdisc_run(q);
 
@@ -2084,7 +2090,8 @@ static int ing_filter(struct sk_buff *skb)
 	q = rxq->qdisc;
 	if (q != &noop_qdisc) {
 		spin_lock(qdisc_lock(q));
-		result = qdisc_enqueue_root(skb, q);
+		if (likely(!test_bit(__QDISC_STATE_DEACTIVATED, &q->state)))
+			result = qdisc_enqueue_root(skb, q);
 		spin_unlock(qdisc_lock(q));
 	}