[NET]: Fix dev->qdisc race for NETDEV_TX_LOCKED case

[net-next-2.6.git] / net / sched / sch_generic.c

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 52eb3439d7c6bf561dc88fca37fdaea0e8a1da4b..a8240c578772d402ea8bd510f901ff25154e4f66 100644 (file)
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -36,34 +36,27 @@
 
 /* Main transmission queue. */
 
-/* Main qdisc structure lock.
-
-   However, modifications
-   to data, participating in scheduling must be additionally
-   protected with dev->queue_lock spinlock.
-
-   The idea is the following:
-   - enqueue, dequeue are serialized via top level device
-     spinlock dev->queue_lock.
-   - tree walking is protected by read_lock(qdisc_tree_lock)
-     and this lock is used only in process context.
-   - updates to tree are made only under rtnl semaphore,
-     hence this lock may be made without local bh disabling.
-
-   qdisc_tree_lock must be grabbed BEFORE dev->queue_lock!
+/* Modifications to data participating in scheduling must be protected with
+ * dev->queue_lock spinlock.
+ *
+ * The idea is the following:
+ * - enqueue, dequeue are serialized via top level device
+ *   spinlock dev->queue_lock.
+ * - ingress filtering is serialized via top level device
+ *   spinlock dev->ingress_lock.
+ * - updates to tree and tree walking are only done under the rtnl mutex.
  */
-DEFINE_RWLOCK(qdisc_tree_lock);
 
 void qdisc_lock_tree(struct net_device *dev)
 {
-       write_lock(&qdisc_tree_lock);
        spin_lock_bh(&dev->queue_lock);
+       spin_lock(&dev->ingress_lock);
 }
 
 void qdisc_unlock_tree(struct net_device *dev)
 {
+       spin_unlock(&dev->ingress_lock);
        spin_unlock_bh(&dev->queue_lock);
-       write_unlock(&qdisc_tree_lock);
 }
 
 /*
@@ -146,6 +139,7 @@ static inline int qdisc_restart(struct net_device *dev)
                                }
                                if (ret == NETDEV_TX_LOCKED && nolock) {
                                        spin_lock(&dev->queue_lock);
+                                       q = dev->qdisc;
                                        goto collision;
                                }
                        }
@@ -442,7 +436,6 @@ struct Qdisc *qdisc_alloc(struct net_device *dev, struct Qdisc_ops *ops)
        sch->dequeue = ops->dequeue;
        sch->dev = dev;
        dev_hold(dev);
-       sch->stats_lock = &dev->queue_lock;
        atomic_set(&sch->refcnt, 1);
 
        return sch;
@@ -458,6 +451,7 @@ struct Qdisc * qdisc_create_dflt(struct net_device *dev, struct Qdisc_ops *ops,
        sch = qdisc_alloc(dev, ops);
        if (IS_ERR(sch))
                goto errout;
+       sch->stats_lock = &dev->queue_lock;
        sch->parent = parentid;
 
        if (!ops->init || ops->init(sch, NULL) == 0)
@@ -528,15 +522,11 @@ void dev_activate(struct net_device *dev)
                                printk(KERN_INFO "%s: activation failed\n", dev->name);
                                return;
                        }
-                       write_lock(&qdisc_tree_lock);
                        list_add_tail(&qdisc->list, &dev->qdisc_list);
-                       write_unlock(&qdisc_tree_lock);
                } else {
                        qdisc =  &noqueue_qdisc;
                }
-               write_lock(&qdisc_tree_lock);
                dev->qdisc_sleeping = qdisc;
-               write_unlock(&qdisc_tree_lock);
        }
 
        if (!netif_carrier_ok(dev))