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>

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index a7abfda..757ab08 100644 (file)
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -27,6 +27,7 @@ enum qdisc_state_t
 {
        __QDISC_STATE_RUNNING,
        __QDISC_STATE_SCHED,
+       __QDISC_STATE_DEACTIVATED,
 };
 
 struct qdisc_size_table {

diff --git a/net/core/dev.c b/net/core/dev.c
index 600bb23..d9e31f6 100644 (file)
--- 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));
        }
 

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 4685746..ff1c455 100644 (file)
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -597,6 +597,9 @@ static void transition_one_qdisc(struct net_device *dev,
        struct Qdisc *new_qdisc = dev_queue->qdisc_sleeping;
        int *need_watchdog_p = _need_watchdog;
 
+       if (!(new_qdisc->flags & TCQ_F_BUILTIN))
+               clear_bit(__QDISC_STATE_DEACTIVATED, &new_qdisc->state);
+
        rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
        if (need_watchdog_p && new_qdisc != &noqueue_qdisc)
                *need_watchdog_p = 1;
@@ -640,6 +643,9 @@ static void dev_deactivate_queue(struct net_device *dev,
        if (qdisc) {
                spin_lock_bh(qdisc_lock(qdisc));
 
+               if (!(qdisc->flags & TCQ_F_BUILTIN))
+                       set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);
+
                dev_queue->qdisc = qdisc_default;
                qdisc_reset(qdisc);