pkt_sched: Remove useless qdisc_stab_lock

The qdisc_stab_lock is used in qdisc_get_stab and qdisc_put_stab.
These two functions are invoked in qdisc_create, qdisc_change, and
qdisc_destroy which run fully under RTNL.

So it already makes sure only one could access the qdisc_stab_list at
the same time. Then it is unnecessary to use qdisc_stab_lock now.

Signed-off-by: Gao Feng <fgao@ikuai8.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index a13c15e8f08782f9a428690052bf5585c446b6fe..bcf49cd2278670197f2a7e9d4e9a62ae8d117468 100644 (file)
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -440,7 +440,6 @@ void qdisc_put_rtab(struct qdisc_rate_table *tab)
 EXPORT_SYMBOL(qdisc_put_rtab);
 
 static LIST_HEAD(qdisc_stab_list);
-static DEFINE_SPINLOCK(qdisc_stab_lock);
 
 static const struct nla_policy stab_policy[TCA_STAB_MAX + 1] = {
        [TCA_STAB_BASE] = { .len = sizeof(struct tc_sizespec) },
@@ -474,20 +473,15 @@ static struct qdisc_size_table *qdisc_get_stab(struct nlattr *opt)
        if (tsize != s->tsize || (!tab && tsize > 0))
                return ERR_PTR(-EINVAL);
 
-       spin_lock(&qdisc_stab_lock);
-
        list_for_each_entry(stab, &qdisc_stab_list, list) {
                if (memcmp(&stab->szopts, s, sizeof(*s)))
                        continue;
                if (tsize > 0 && memcmp(stab->data, tab, tsize * sizeof(u16)))
                        continue;
                stab->refcnt++;
-               spin_unlock(&qdisc_stab_lock);
                return stab;
        }
 
-       spin_unlock(&qdisc_stab_lock);
-
        stab = kmalloc(sizeof(*stab) + tsize * sizeof(u16), GFP_KERNEL);
        if (!stab)
                return ERR_PTR(-ENOMEM);
@@ -497,9 +491,7 @@ static struct qdisc_size_table *qdisc_get_stab(struct nlattr *opt)
        if (tsize > 0)
                memcpy(stab->data, tab, tsize * sizeof(u16));
 
-       spin_lock(&qdisc_stab_lock);
        list_add_tail(&stab->list, &qdisc_stab_list);
-       spin_unlock(&qdisc_stab_lock);
 
        return stab;
 }
@@ -514,14 +506,10 @@ void qdisc_put_stab(struct qdisc_size_table *tab)
        if (!tab)
                return;
 
-       spin_lock(&qdisc_stab_lock);
-
        if (--tab->refcnt == 0) {
                list_del(&tab->list);
                call_rcu_bh(&tab->rcu, stab_kfree_rcu);
        }
-
-       spin_unlock(&qdisc_stab_lock);
 }
 EXPORT_SYMBOL(qdisc_put_stab);