pkt_sched: Make qdisc grafting locking more specific.

Lock the root of the qdisc being operated upon.

All explicit references to qdisc_tree_lock() are now gone.
The only remaining uses are via the sch_tree_{lock,unlock}()
and tcf_tree_{lock,unlock}() macros.

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

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 6958fe7c9a775333fbca7f82ddf0bc29bd9e4132..74924893ef7f7f8f28ef1ff24f6a6ca2dbe1bfe4 100644 (file)
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -441,15 +441,29 @@ static struct Qdisc *
 dev_graft_qdisc(struct net_device *dev, struct Qdisc *qdisc)
 {
        struct netdev_queue *dev_queue;
+       spinlock_t *root_lock;
        struct Qdisc *oqdisc;
+       int ingress;
 
        if (dev->flags & IFF_UP)
                dev_deactivate(dev);
 
-       qdisc_lock_tree(dev);
-       if (qdisc && qdisc->flags&TCQ_F_INGRESS) {
+       ingress = 0;
+       if (qdisc && qdisc->flags&TCQ_F_INGRESS)
+               ingress = 1;
+
+       if (ingress) {
                dev_queue = &dev->rx_queue;
                oqdisc = dev_queue->qdisc;
+       } else {
+               dev_queue = netdev_get_tx_queue(dev, 0);
+               oqdisc = dev_queue->qdisc_sleeping;
+       }
+
+       root_lock = qdisc_root_lock(oqdisc);
+       spin_lock_bh(root_lock);
+
+       if (ingress) {
                /* Prune old scheduler */
                if (oqdisc && atomic_read(&oqdisc->refcnt) <= 1) {
                        /* delete */
@@ -460,9 +474,6 @@ dev_graft_qdisc(struct net_device *dev, struct Qdisc *qdisc)
                }
 
        } else {
-               dev_queue = netdev_get_tx_queue(dev, 0);
-               oqdisc = dev_queue->qdisc_sleeping;
-
                /* Prune old scheduler */
                if (oqdisc && atomic_read(&oqdisc->refcnt) <= 1)
                        qdisc_reset(oqdisc);
@@ -474,7 +485,7 @@ dev_graft_qdisc(struct net_device *dev, struct Qdisc *qdisc)
                dev_queue->qdisc = &noop_qdisc;
        }
 
-       qdisc_unlock_tree(dev);
+       spin_unlock_bh(root_lock);
 
        if (dev->flags & IFF_UP)
                dev_activate(dev);
@@ -765,10 +776,12 @@ static int tc_get_qdisc(struct sk_buff *skb, struct nlmsghdr *n, void *arg)
                if ((err = qdisc_graft(dev, p, clid, NULL, &q)) != 0)
                        return err;
                if (q) {
+                       spinlock_t *root_lock = qdisc_root_lock(q);
+
                        qdisc_notify(skb, n, clid, q, NULL);
-                       qdisc_lock_tree(dev);
+                       spin_unlock_bh(root_lock);
                        qdisc_destroy(q);
-                       qdisc_unlock_tree(dev);
+                       spin_unlock_bh(root_lock);
                }
        } else {
                qdisc_notify(skb, n, clid, NULL, q);
@@ -911,20 +924,24 @@ create_n_graft:
 graft:
        if (1) {
                struct Qdisc *old_q = NULL;
+               spinlock_t *root_lock;
+
                err = qdisc_graft(dev, p, clid, q, &old_q);
                if (err) {
                        if (q) {
-                               qdisc_lock_tree(dev);
+                               root_lock = qdisc_root_lock(q);
+                               spin_lock_bh(root_lock);
                                qdisc_destroy(q);
-                               qdisc_unlock_tree(dev);
+                               spin_unlock_bh(root_lock);
                        }
                        return err;
                }
                qdisc_notify(skb, n, clid, old_q, q);
                if (old_q) {
-                       qdisc_lock_tree(dev);
+                       root_lock = qdisc_root_lock(old_q);
+                       spin_lock_bh(root_lock);
                        qdisc_destroy(old_q);
-                       qdisc_unlock_tree(dev);
+                       spin_unlock_bh(root_lock);
                }
        }
        return 0;