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net: sched: fix qdisc->running lockdep annotations

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1) qdisc_run_begin() is really using the equivalent of a trylock.
  Instead of using write_seqcount_begin(), use a combination of
  raw_write_seqcount_begin() and correct lockdep annotation.

2) sch_direct_xmit() should use regular spin_lock(root_lock)

Fixes: f9eb8aea2a ("net_sched: transform qdisc running bit into a seqcount")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2016-06-09 07:45:11 -07:00 committed by David S. Miller
parent 5362855aba
commit 52fbb29079
2 changed files with 7 additions and 3 deletions
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6
include/net/sch_generic.h
View file

@ -97,7 +97,11 @@ static inline bool qdisc_run_begin(struct Qdisc *qdisc)
{
if (qdisc_is_running(qdisc))
return false;
write_seqcount_begin(&qdisc->running);
/* Variant of write_seqcount_begin() telling lockdep a trylock
* was attempted.
*/
raw_write_seqcount_begin(&qdisc->running);
seqcount_acquire(&qdisc->running.dep_map, 0, 1, _RET_IP_);
return true;
}

4
net/sched/sch_generic.c
View file

@ -137,10 +137,10 @@ int sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
HARD_TX_UNLOCK(dev, txq);
} else {
spin_lock_nested(root_lock, SINGLE_DEPTH_NESTING);
spin_lock(root_lock);
return qdisc_qlen(q);
}
spin_lock_nested(root_lock, SINGLE_DEPTH_NESTING);
spin_lock(root_lock);
if (dev_xmit_complete(ret)) {
/* Driver sent out skb successfully or skb was consumed */