net: sched: convert qdisc linked list to hashtable

Convert the per-device linked list into a hashtable. The primary
motivation for this change is that currently, we're not tracking all the
qdiscs in hierarchy (e.g. excluding default qdiscs), as the lookup
performed over the linked list by qdisc_match_from_root() is rather
expensive.

The ultimate goal is to get rid of hidden qdiscs completely, which will
bring much more determinism in user experience.

Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 076df53..96e0b6c 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -52,6 +52,7 @@
 #include <uapi/linux/netdevice.h>
 #include <uapi/linux/if_bonding.h>
 #include <uapi/linux/pkt_cls.h>
+#include <linux/hashtable.h>
 
 struct netpoll_info;
 struct device;
@@ -1800,6 +1801,9 @@ struct net_device {
        unsigned int            num_tx_queues;
        unsigned int            real_num_tx_queues;
        struct Qdisc            *qdisc;
+#ifdef CONFIG_NET_SCHED
+       DECLARE_HASHTABLE       (qdisc_hash, 4);
+#endif
        unsigned long           tx_queue_len;
        spinlock_t              tx_global_lock;
        int                     watchdog_timeo;

diff --git a/include/net/pkt_sched.h b/include/net/pkt_sched.h
index 7caa99b..cd334c9 100644 (file)
--- a/include/net/pkt_sched.h
+++ b/include/net/pkt_sched.h
@@ -90,8 +90,8 @@ int unregister_qdisc(struct Qdisc_ops *qops);
 void qdisc_get_default(char *id, size_t len);
 int qdisc_set_default(const char *id);
 
-void qdisc_list_add(struct Qdisc *q);
-void qdisc_list_del(struct Qdisc *q);
+void qdisc_hash_add(struct Qdisc *q);
+void qdisc_hash_del(struct Qdisc *q);
 struct Qdisc *qdisc_lookup(struct net_device *dev, u32 handle);
 struct Qdisc *qdisc_lookup_class(struct net_device *dev, u32 handle);
 struct qdisc_rate_table *qdisc_get_rtab(struct tc_ratespec *r,

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 909aff2..0d50177 100644 (file)
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -61,7 +61,7 @@ struct Qdisc {
        u32                     limit;
        const struct Qdisc_ops  *ops;
        struct qdisc_size_table __rcu *stab;
-       struct list_head        list;
+       struct hlist_node       hash;
        u32                     handle;
        u32                     parent;
        void                    *u32_node;

diff --git a/net/core/dev.c b/net/core/dev.c
index 4ce07dc..936ea00 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7629,6 +7629,9 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
        INIT_LIST_HEAD(&dev->all_adj_list.lower);
        INIT_LIST_HEAD(&dev->ptype_all);
        INIT_LIST_HEAD(&dev->ptype_specific);
+#ifdef CONFIG_NET_SCHED
+       hash_init(dev->qdisc_hash);
+#endif
        dev->priv_flags = IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM;
        setup(dev);
 

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 12ebde8..25aada7 100644 (file)
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -29,6 +29,7 @@
 #include <linux/hrtimer.h>
 #include <linux/lockdep.h>
 #include <linux/slab.h>
+#include <linux/hashtable.h>
 
 #include <net/net_namespace.h>
 #include <net/sock.h>
@@ -263,33 +264,33 @@ static struct Qdisc *qdisc_match_from_root(struct Qdisc *root, u32 handle)
            root->handle == handle)
                return root;
 
-       list_for_each_entry_rcu(q, &root->list, list) {
+       hash_for_each_possible_rcu(qdisc_dev(root)->qdisc_hash, q, hash, handle) {
                if (q->handle == handle)
                        return q;
        }
        return NULL;
 }
 
-void qdisc_list_add(struct Qdisc *q)
+void qdisc_hash_add(struct Qdisc *q)
 {
        if ((q->parent != TC_H_ROOT) && !(q->flags & TCQ_F_INGRESS)) {
                struct Qdisc *root = qdisc_dev(q)->qdisc;
 
                WARN_ON_ONCE(root == &noop_qdisc);
                ASSERT_RTNL();
-               list_add_tail_rcu(&q->list, &root->list);
+               hash_add_rcu(qdisc_dev(q)->qdisc_hash, &q->hash, q->handle);
        }
 }
-EXPORT_SYMBOL(qdisc_list_add);
+EXPORT_SYMBOL(qdisc_hash_add);
 
-void qdisc_list_del(struct Qdisc *q)
+void qdisc_hash_del(struct Qdisc *q)
 {
        if ((q->parent != TC_H_ROOT) && !(q->flags & TCQ_F_INGRESS)) {
                ASSERT_RTNL();
-               list_del_rcu(&q->list);
+               hash_del_rcu(&q->hash);
        }
 }
-EXPORT_SYMBOL(qdisc_list_del);
+EXPORT_SYMBOL(qdisc_hash_del);
 
 struct Qdisc *qdisc_lookup(struct net_device *dev, u32 handle)
 {
@@ -998,7 +999,7 @@ qdisc_create(struct net_device *dev, struct netdev_queue *dev_queue,
                                goto err_out4;
                }
 
-               qdisc_list_add(sch);
+               qdisc_hash_add(sch);
 
                return sch;
        }
@@ -1435,6 +1436,7 @@ static int tc_dump_qdisc_root(struct Qdisc *root, struct sk_buff *skb,
 {
        int ret = 0, q_idx = *q_idx_p;
        struct Qdisc *q;
+       int b;
 
        if (!root)
                return 0;
@@ -1449,7 +1451,7 @@ static int tc_dump_qdisc_root(struct Qdisc *root, struct sk_buff *skb,
                        goto done;
                q_idx++;
        }
-       list_for_each_entry(q, &root->list, list) {
+       hash_for_each(qdisc_dev(root)->qdisc_hash, b, q, hash) {
                if (q_idx < s_q_idx) {
                        q_idx++;
                        continue;
@@ -1765,6 +1767,7 @@ static int tc_dump_tclass_root(struct Qdisc *root, struct sk_buff *skb,
                               int *t_p, int s_t)
 {
        struct Qdisc *q;
+       int b;
 
        if (!root)
                return 0;
@@ -1772,7 +1775,7 @@ static int tc_dump_tclass_root(struct Qdisc *root, struct sk_buff *skb,
        if (tc_dump_tclass_qdisc(root, skb, tcm, cb, t_p, s_t) < 0)
                return -1;
 
-       list_for_each_entry(q, &root->list, list) {
+       hash_for_each(qdisc_dev(root)->qdisc_hash, b, q, hash) {
                if (tc_dump_tclass_qdisc(q, skb, tcm, cb, t_p, s_t) < 0)
                        return -1;
        }

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index e95b67c..18faecc 100644 (file)
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -423,7 +423,6 @@ struct Qdisc noop_qdisc = {
        .dequeue        =       noop_dequeue,
        .flags          =       TCQ_F_BUILTIN,
        .ops            =       &noop_qdisc_ops,
-       .list           =       LIST_HEAD_INIT(noop_qdisc.list),
        .q.lock         =       __SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
        .dev_queue      =       &noop_netdev_queue,
        .running        =       SEQCNT_ZERO(noop_qdisc.running),
@@ -613,7 +612,6 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
                sch = (struct Qdisc *) QDISC_ALIGN((unsigned long) p);
                sch->padded = (char *) sch - (char *) p;
        }
-       INIT_LIST_HEAD(&sch->list);
        skb_queue_head_init(&sch->q);
 
        spin_lock_init(&sch->busylock);
@@ -700,7 +698,7 @@ void qdisc_destroy(struct Qdisc *qdisc)
                return;
 
 #ifdef CONFIG_NET_SCHED
-       qdisc_list_del(qdisc);
+       qdisc_hash_del(qdisc);
 
        qdisc_put_stab(rtnl_dereference(qdisc->stab));
 #endif
@@ -788,6 +786,10 @@ static void attach_default_qdiscs(struct net_device *dev)
                        qdisc->ops->attach(qdisc);
                }
        }
+#ifdef CONFIG_NET_SCHED
+       if (dev->qdisc)
+               qdisc_hash_add(dev->qdisc);
+#endif
 }
 
 static void transition_one_qdisc(struct net_device *dev,

diff --git a/net/sched/sch_mq.c b/net/sched/sch_mq.c
index b943982..2bc8d7f 100644 (file)
--- a/net/sched/sch_mq.c
+++ b/net/sched/sch_mq.c
@@ -88,7 +88,7 @@ static void mq_attach(struct Qdisc *sch)
                        qdisc_destroy(old);
 #ifdef CONFIG_NET_SCHED
                if (ntx < dev->real_num_tx_queues)
-                       qdisc_list_add(qdisc);
+                       qdisc_hash_add(qdisc);
 #endif
 
        }

diff --git a/net/sched/sch_mqprio.c b/net/sched/sch_mqprio.c
index 549c663..b5c502c 100644 (file)
--- a/net/sched/sch_mqprio.c
+++ b/net/sched/sch_mqprio.c
@@ -182,7 +182,7 @@ static void mqprio_attach(struct Qdisc *sch)
                if (old)
                        qdisc_destroy(old);
                if (ntx < dev->real_num_tx_queues)
-                       qdisc_list_add(qdisc);
+                       qdisc_hash_add(qdisc);
        }
        kfree(priv->qdiscs);
        priv->qdiscs = NULL;