net_sched: transform qdisc running bit into a seqcount
Instead of using a single bit (__QDISC___STATE_RUNNING)
in sch->__state, use a seqcount.
This adds lockdep support, but more importantly it will allow us
to sample qdisc/class statistics without having to grab qdisc root lock.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 941ec99..681af31 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -4610,6 +4610,7 @@
static struct lock_class_key bonding_netdev_xmit_lock_key;
static struct lock_class_key bonding_netdev_addr_lock_key;
static struct lock_class_key bonding_tx_busylock_key;
+static struct lock_class_key bonding_qdisc_running_key;
static void bond_set_lockdep_class_one(struct net_device *dev,
struct netdev_queue *txq,
@@ -4625,6 +4626,7 @@
&bonding_netdev_addr_lock_key);
netdev_for_each_tx_queue(dev, bond_set_lockdep_class_one, NULL);
dev->qdisc_tx_busylock = &bonding_tx_busylock_key;
+ dev->qdisc_running_key = &bonding_qdisc_running_key;
}
/* Called from registration process */
diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 8dedafa..aeabaa4 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -1313,9 +1313,12 @@
}
static struct lock_class_key ppp_tx_busylock;
+static struct lock_class_key ppp_qdisc_running_key;
+
static int ppp_dev_init(struct net_device *dev)
{
dev->qdisc_tx_busylock = &ppp_tx_busylock;
+ dev->qdisc_running_key = &ppp_qdisc_running_key;
return 0;
}
diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c
index 2ace126..00eb389 100644
--- a/drivers/net/team/team.c
+++ b/drivers/net/team/team.c
@@ -1577,6 +1577,7 @@
static struct lock_class_key team_netdev_xmit_lock_key;
static struct lock_class_key team_netdev_addr_lock_key;
static struct lock_class_key team_tx_busylock_key;
+static struct lock_class_key team_qdisc_running_key;
static void team_set_lockdep_class_one(struct net_device *dev,
struct netdev_queue *txq,
@@ -1590,6 +1591,7 @@
lockdep_set_class(&dev->addr_list_lock, &team_netdev_addr_lock_key);
netdev_for_each_tx_queue(dev, team_set_lockdep_class_one, NULL);
dev->qdisc_tx_busylock = &team_tx_busylock_key;
+ dev->qdisc_running_key = &team_qdisc_running_key;
}
static int team_init(struct net_device *dev)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index fa6df26..59d7e06 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1862,6 +1862,7 @@
#endif
struct phy_device *phydev;
struct lock_class_key *qdisc_tx_busylock;
+ struct lock_class_key *qdisc_running_key;
bool proto_down;
};
#define to_net_dev(d) container_of(d, struct net_device, dev)
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index a1fd76c..bff8d89 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -29,13 +29,6 @@
__QDISC_STATE_THROTTLED,
};
-/*
- * following bits are only changed while qdisc lock is held
- */
-enum qdisc___state_t {
- __QDISC___STATE_RUNNING = 1,
-};
-
struct qdisc_size_table {
struct rcu_head rcu;
struct list_head list;
@@ -93,7 +86,7 @@
unsigned long state;
struct sk_buff_head q;
struct gnet_stats_basic_packed bstats;
- unsigned int __state;
+ seqcount_t running;
struct gnet_stats_queue qstats;
struct rcu_head rcu_head;
int padded;
@@ -104,20 +97,20 @@
static inline bool qdisc_is_running(const struct Qdisc *qdisc)
{
- return (qdisc->__state & __QDISC___STATE_RUNNING) ? true : false;
+ return (raw_read_seqcount(&qdisc->running) & 1) ? true : false;
}
static inline bool qdisc_run_begin(struct Qdisc *qdisc)
{
if (qdisc_is_running(qdisc))
return false;
- qdisc->__state |= __QDISC___STATE_RUNNING;
+ write_seqcount_begin(&qdisc->running);
return true;
}
static inline void qdisc_run_end(struct Qdisc *qdisc)
{
- qdisc->__state &= ~__QDISC___STATE_RUNNING;
+ write_seqcount_end(&qdisc->running);
}
static inline bool qdisc_may_bulk(const struct Qdisc *qdisc)
diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c
index 780089d..977a11e 100644
--- a/net/bluetooth/6lowpan.c
+++ b/net/bluetooth/6lowpan.c
@@ -629,6 +629,7 @@
static struct lock_class_key bt_tx_busylock;
static struct lock_class_key bt_netdev_xmit_lock_key;
+static struct lock_class_key bt_qdisc_running_key;
static void bt_set_lockdep_class_one(struct net_device *dev,
struct netdev_queue *txq,
@@ -641,6 +642,7 @@
{
netdev_for_each_tx_queue(dev, bt_set_lockdep_class_one, NULL);
dev->qdisc_tx_busylock = &bt_tx_busylock;
+ dev->qdisc_running_key = &bt_qdisc_running_key;
return 0;
}
diff --git a/net/core/dev.c b/net/core/dev.c
index 896b686..e0bcc39 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3075,7 +3075,7 @@
/*
* Heuristic to force contended enqueues to serialize on a
* separate lock before trying to get qdisc main lock.
- * This permits __QDISC___STATE_RUNNING owner to get the lock more
+ * This permits qdisc->running owner to get the lock more
* often and dequeue packets faster.
*/
contended = qdisc_is_running(q);
diff --git a/net/ieee802154/6lowpan/core.c b/net/ieee802154/6lowpan/core.c
index dd085db..14aa5ef 100644
--- a/net/ieee802154/6lowpan/core.c
+++ b/net/ieee802154/6lowpan/core.c
@@ -60,6 +60,7 @@
static struct lock_class_key lowpan_tx_busylock;
static struct lock_class_key lowpan_netdev_xmit_lock_key;
+static struct lock_class_key lowpan_qdisc_running_key;
static void lowpan_set_lockdep_class_one(struct net_device *ldev,
struct netdev_queue *txq,
@@ -73,6 +74,8 @@
{
netdev_for_each_tx_queue(ldev, lowpan_set_lockdep_class_one, NULL);
ldev->qdisc_tx_busylock = &lowpan_tx_busylock;
+ ldev->qdisc_running_key = &lowpan_qdisc_running_key;
+
return 0;
}
diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c
index e253c26..c00d72d 100644
--- a/net/l2tp/l2tp_eth.c
+++ b/net/l2tp/l2tp_eth.c
@@ -68,6 +68,8 @@
}
static struct lock_class_key l2tp_eth_tx_busylock;
+static struct lock_class_key l2tp_qdisc_running_key;
+
static int l2tp_eth_dev_init(struct net_device *dev)
{
struct l2tp_eth *priv = netdev_priv(dev);
@@ -76,6 +78,8 @@
eth_hw_addr_random(dev);
eth_broadcast_addr(dev->broadcast);
dev->qdisc_tx_busylock = &l2tp_eth_tx_busylock;
+ dev->qdisc_running_key = &l2tp_qdisc_running_key;
+
return 0;
}
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 269dd71..cebea73 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -110,7 +110,7 @@
/*
* Transmit possibly several skbs, and handle the return status as
- * required. Holding the __QDISC___STATE_RUNNING bit guarantees that
+ * required. Owning running seqcount bit guarantees that
* only one CPU can execute this function.
*
* Returns to the caller:
@@ -137,10 +137,10 @@
HARD_TX_UNLOCK(dev, txq);
} else {
- spin_lock(root_lock);
+ spin_lock_nested(root_lock, SINGLE_DEPTH_NESTING);
return qdisc_qlen(q);
}
- spin_lock(root_lock);
+ spin_lock_nested(root_lock, SINGLE_DEPTH_NESTING);
if (dev_xmit_complete(ret)) {
/* Driver sent out skb successfully or skb was consumed */
@@ -163,7 +163,7 @@
/*
* NOTE: Called under qdisc_lock(q) with locally disabled BH.
*
- * __QDISC___STATE_RUNNING guarantees only one CPU can process
+ * running seqcount guarantees only one CPU can process
* this qdisc at a time. qdisc_lock(q) serializes queue accesses for
* this queue.
*
@@ -379,6 +379,7 @@
.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),
.busylock = __SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
};
EXPORT_SYMBOL(noop_qdisc);
@@ -537,6 +538,7 @@
EXPORT_SYMBOL(pfifo_fast_ops);
static struct lock_class_key qdisc_tx_busylock;
+static struct lock_class_key qdisc_running_key;
struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
const struct Qdisc_ops *ops)
@@ -570,6 +572,10 @@
lockdep_set_class(&sch->busylock,
dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
+ seqcount_init(&sch->running);
+ lockdep_set_class(&sch->running,
+ dev->qdisc_running_key ?: &qdisc_running_key);
+
sch->ops = ops;
sch->enqueue = ops->enqueue;
sch->dequeue = ops->dequeue;