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Diffstat (limited to 'net')
-rw-r--r--net/sched/sch_generic.c26
1 files changed, 23 insertions, 3 deletions
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index e01d57692c9..fa1a6f45dc4 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -556,6 +556,7 @@ void dev_deactivate(struct net_device *dev)
{
struct Qdisc *qdisc;
struct sk_buff *skb;
+ int running;
spin_lock_bh(&dev->queue_lock);
qdisc = dev->qdisc;
@@ -571,12 +572,31 @@ void dev_deactivate(struct net_device *dev)
dev_watchdog_down(dev);
- /* Wait for outstanding dev_queue_xmit calls. */
+ /* Wait for outstanding qdisc-less dev_queue_xmit calls. */
synchronize_rcu();
/* Wait for outstanding qdisc_run calls. */
- while (test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state))
- yield();
+ do {
+ while (test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state))
+ yield();
+
+ /*
+ * Double-check inside queue lock to ensure that all effects
+ * of the queue run are visible when we return.
+ */
+ spin_lock_bh(&dev->queue_lock);
+ running = test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state);
+ spin_unlock_bh(&dev->queue_lock);
+
+ /*
+ * The running flag should never be set at this point because
+ * we've already set dev->qdisc to noop_qdisc *inside* the same
+ * pair of spin locks. That is, if any qdisc_run starts after
+ * our initial test it should see the noop_qdisc and then
+ * clear the RUNNING bit before dropping the queue lock. So
+ * if it is set here then we've found a bug.
+ */
+ } while (WARN_ON_ONCE(running));
}
void dev_init_scheduler(struct net_device *dev)