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| author | Eric Dumazet <edumazet@google.com> | 2014-03-05 10:14:34 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-03-06 17:24:54 -0500 |
| commit | 6f542efcbc74801eb4bfa0dbba64c2df6811b2d3 (patch) | |
| tree | de599fdf0df82a87994f7c4c91e11acf3885614d | |
| parent | e86800f9201d35b6b2aac1583a9bf9e3a0b0c70d (diff) | |
| download | linux-6f542efcbc74801eb4bfa0dbba64c2df6811b2d3.tar.gz linux-6f542efcbc74801eb4bfa0dbba64c2df6811b2d3.tar.bz2 linux-6f542efcbc74801eb4bfa0dbba64c2df6811b2d3.zip | |
net_sched: htb: do not acquire qdisc lock in dump operations
htb_dump() and htb_dump_class() do not strictly need to acquire
qdisc lock to fetch qdisc and/or class parameters.
We hold RTNL and no changes can occur.
This reduces by 50% qdisc lock pressure while doing tc qdisc|class dump
operations.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/sched/sch_htb.c | 20 |
1 files changed, 8 insertions, 12 deletions
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c index 722e137df244..9f949abcacef 100644 --- a/net/sched/sch_htb.c +++ b/net/sched/sch_htb.c @@ -1062,12 +1062,13 @@ 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_sleeping_lock(sch); struct htb_sched *q = qdisc_priv(sch); struct nlattr *nest; struct tc_htb_glob gopt; - spin_lock_bh(root_lock); + /* Its safe to not acquire qdisc lock. As we hold RTNL, + * no change can happen on the qdisc parameters. + */ gopt.direct_pkts = q->direct_pkts; gopt.version = HTB_VER; @@ -1081,13 +1082,10 @@ static int htb_dump(struct Qdisc *sch, struct sk_buff *skb) if (nla_put(skb, TCA_HTB_INIT, sizeof(gopt), &gopt) || nla_put_u32(skb, TCA_HTB_DIRECT_QLEN, q->direct_qlen)) goto nla_put_failure; - nla_nest_end(skb, nest); - spin_unlock_bh(root_lock); - return skb->len; + return nla_nest_end(skb, nest); nla_put_failure: - spin_unlock_bh(root_lock); nla_nest_cancel(skb, nest); return -1; } @@ -1096,11 +1094,12 @@ 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_sleeping_lock(sch); struct nlattr *nest; struct tc_htb_opt opt; - spin_lock_bh(root_lock); + /* Its safe to not acquire qdisc lock. As we hold RTNL, + * no change can happen on the class parameters. + */ 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) @@ -1128,12 +1127,9 @@ static int htb_dump_class(struct Qdisc *sch, unsigned long arg, nla_put_u64(skb, TCA_HTB_CEIL64, cl->ceil.rate_bytes_ps)) goto nla_put_failure; - nla_nest_end(skb, nest); - spin_unlock_bh(root_lock); - return skb->len; + return nla_nest_end(skb, nest); nla_put_failure: - spin_unlock_bh(root_lock); nla_nest_cancel(skb, nest); return -1; } |