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pkt_sched: Add and use qdisc_root() and qdisc_root_lock().

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When code wants to lock the qdisc tree state, the logic
operation it's doing is locking the top-level qdisc that
sits of the root of the netdev_queue.

Add qdisc_root_lock() to represent this and convert the
easiest cases.

In order for this to work out in all cases, we have to
hook up the noop_qdisc to a dummy netdev_queue.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller
2008-07-16 01:42:40 -07:00
parent e2627c8c22
commit 7698b4fcab
7 changed files with 55 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
net/sched/sch_htb.c
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@@ -1039,11 +1039,12 @@ static int htb_init(struct Qdisc *sch, struct nlattr *opt)
static int htb_dump(struct Qdisc *sch, struct sk_buff *skb)
{
spinlock_t *root_lock = qdisc_root_lock(sch);
struct htb_sched *q = qdisc_priv(sch);
struct nlattr *nest;
struct tc_htb_glob gopt;
spin_lock_bh(&sch->dev_queue->lock);
spin_lock_bh(root_lock);
gopt.direct_pkts = q->direct_pkts;
gopt.version = HTB_VER;
@@ -1057,11 +1058,11 @@ static int htb_dump(struct Qdisc *sch, struct sk_buff *skb)
NLA_PUT(skb, TCA_HTB_INIT, sizeof(gopt), &gopt);
nla_nest_end(skb, nest);
spin_unlock_bh(&sch->dev_queue->lock);
spin_unlock_bh(root_lock);
return skb->len;
nla_put_failure:
spin_unlock_bh(&sch->dev_queue->lock);
spin_unlock_bh(root_lock);
nla_nest_cancel(skb, nest);
return -1;
}
@@ -1070,10 +1071,11 @@ static int htb_dump_class(struct Qdisc *sch, unsigned long arg,
struct sk_buff *skb, struct tcmsg *tcm)
{
struct htb_class *cl = (struct htb_class *)arg;
spinlock_t *root_lock = qdisc_root_lock(sch);
struct nlattr *nest;
struct tc_htb_opt opt;
spin_lock_bh(&sch->dev_queue->lock);
spin_lock_bh(root_lock);
tcm->tcm_parent = cl->parent ? cl->parent->common.classid : TC_H_ROOT;
tcm->tcm_handle = cl->common.classid;
if (!cl->level && cl->un.leaf.q)
@@ -1095,11 +1097,11 @@ static int htb_dump_class(struct Qdisc *sch, unsigned long arg,
NLA_PUT(skb, TCA_HTB_PARMS, sizeof(opt), &opt);
nla_nest_end(skb, nest);
spin_unlock_bh(&sch->dev_queue->lock);
spin_unlock_bh(root_lock);
return skb->len;
nla_put_failure:
spin_unlock_bh(&sch->dev_queue->lock);
spin_unlock_bh(root_lock);
nla_nest_cancel(skb, nest);
return -1;
}
@@ -1365,7 +1367,7 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
goto failure;
gen_new_estimator(&cl->bstats, &cl->rate_est,
&sch->dev_queue->lock,
qdisc_root_lock(sch),
tca[TCA_RATE] ? : &est.nla);
cl->refcnt = 1;
cl->children = 0;
@@ -1420,7 +1422,7 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
} else {
if (tca[TCA_RATE])
gen_replace_estimator(&cl->bstats, &cl->rate_est,
&sch->dev_queue->lock,
qdisc_root_lock(sch),
tca[TCA_RATE]);
sch_tree_lock(sch);
}