pkt_sched: Fix queue quiescence testing in dev_deactivate().
Based upon discussions with Jarek P. and Herbert Xu.
First, we're testing the wrong qdisc. We just reset the device
queue qdiscs to &noop_qdisc and checking it's state is completely
pointless here.
We want to wait until the previous qdisc that was sitting at
the ->qdisc pointer is not busy any more. And that would be
->qdisc_sleeping.
Because of how we propagate the samples qdisc pointer down into
qdisc_run and friends via per-cpu ->output_queue and netif_schedule,
we have to wait also for the __QDISC_STATE_SCHED bit to clear as
well.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 7cf83b3..4685746 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -647,7 +647,7 @@
}
}
-static bool some_qdisc_is_running(struct net_device *dev, int lock)
+static bool some_qdisc_is_busy(struct net_device *dev, int lock)
{
unsigned int i;
@@ -658,13 +658,14 @@
int val;
dev_queue = netdev_get_tx_queue(dev, i);
- q = dev_queue->qdisc;
+ q = dev_queue->qdisc_sleeping;
root_lock = qdisc_lock(q);
if (lock)
spin_lock_bh(root_lock);
- val = test_bit(__QDISC_STATE_RUNNING, &q->state);
+ val = (test_bit(__QDISC_STATE_RUNNING, &q->state) ||
+ test_bit(__QDISC_STATE_SCHED, &q->state));
if (lock)
spin_unlock_bh(root_lock);
@@ -689,14 +690,14 @@
/* Wait for outstanding qdisc_run calls. */
do {
- while (some_qdisc_is_running(dev, 0))
+ while (some_qdisc_is_busy(dev, 0))
yield();
/*
* Double-check inside queue lock to ensure that all effects
* of the queue run are visible when we return.
*/
- running = some_qdisc_is_running(dev, 1);
+ running = some_qdisc_is_busy(dev, 1);
/*
* The running flag should never be set at this point because