pkt_sched: Fix OOPS on ingress qdisc add.

Bug report from Steven Jan Springl:

	Issuing the following command causes a kernel oops:
		tc qdisc add dev eth0 handle ffff: ingress

The problem mostly stems from all of the special case handling of
ingress qdiscs.

So, to fix this, do the grafting operation the same way we do for TX
qdiscs.  Which means that dev_activate() and dev_deactivate() now do
the "qdisc_sleeping <--> qdisc" transitions on dev->rx_queue too.

Future simplifications are possible now, mainly because it is
impossible for dev_queue->{qdisc,qdisc_sleeping} to be NULL.  There
are NULL checks all over to handle the ingress qdisc special case
that used to exist before this commit.

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

1 files changed, 5 insertions, 3 deletions

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index fd2a6cadb115..345838a2e369 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -596,7 +596,7 @@ static void transition_one_qdisc(struct net_device *dev,
         int *need_watchdog_p = _need_watchdog;
 
         rcu_assign_pointer(dev_queue->qdisc, new_qdisc);
-        if (new_qdisc != &noqueue_qdisc)
+        if (need_watchdog_p && new_qdisc != &noqueue_qdisc)
                 *need_watchdog_p = 1;
 }
 
@@ -619,6 +619,7 @@ void dev_activate(struct net_device *dev)
 
         need_watchdog = 0;
         netdev_for_each_tx_queue(dev, transition_one_qdisc, &need_watchdog);
+        transition_one_qdisc(dev, &dev->rx_queue, NULL);
 
         if (need_watchdog) {
                 dev->trans_start = jiffies;
@@ -677,6 +678,7 @@ void dev_deactivate(struct net_device *dev)
         bool running;
 
         netdev_for_each_tx_queue(dev, dev_deactivate_queue, &noop_qdisc);
+        dev_deactivate_queue(dev, &dev->rx_queue, &noop_qdisc);
 
         dev_watchdog_down(dev);
 
@@ -718,7 +720,7 @@ static void dev_init_scheduler_queue(struct net_device *dev,
 void dev_init_scheduler(struct net_device *dev)
 {
         netdev_for_each_tx_queue(dev, dev_init_scheduler_queue, &noop_qdisc);
-        dev_init_scheduler_queue(dev, &dev->rx_queue, NULL);
+        dev_init_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc);
 
         setup_timer(&dev->watchdog_timer, dev_watchdog, (unsigned long)dev);
 }
@@ -745,6 +747,6 @@ static void shutdown_scheduler_queue(struct net_device *dev,
 void dev_shutdown(struct net_device *dev)
 {
         netdev_for_each_tx_queue(dev, shutdown_scheduler_queue, &noop_qdisc);
-        shutdown_scheduler_queue(dev, &dev->rx_queue, NULL);
+        shutdown_scheduler_queue(dev, &dev->rx_queue, &noop_qdisc);
         WARN_ON(timer_pending(&dev->watchdog_timer));
 }