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| author | Eric Dumazet <edumazet@google.com> | 2016-06-06 09:37:15 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-06-07 16:37:13 -0700 |
| commit | f9eb8aea2a1e12fc2f584d1627deeb957435a801 (patch) | |
| tree | bc3cf06664da45bc0e6ce9b5165dba534ed11751 /net/sched/sch_generic.c | |
| parent | 64151ae36ed93c45654069c8aff2a7f0125075e8 (diff) | |
| download | lwn-f9eb8aea2a1e12fc2f584d1627deeb957435a801.tar.gz lwn-f9eb8aea2a1e12fc2f584d1627deeb957435a801.zip | |
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>
Diffstat (limited to 'net/sched/sch_generic.c')
| -rw-r--r-- | net/sched/sch_generic.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index 269dd71b3828..cebea73e70ac 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -110,7 +110,7 @@ static struct sk_buff *dequeue_skb(struct Qdisc *q, bool *validate, /* * 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 @@ int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q, 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 @@ int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q, /* * 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 @@ struct Qdisc noop_qdisc = { .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 @@ struct Qdisc_ops pfifo_fast_ops __read_mostly = { 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 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue, 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; |