[RFC Patch net-next 1/6] net_sched: use RCU for action hash table

[Cong Wang]

We already free tc actions in a RCU callback, so here
we just need to convert the hash table operations to
RCU API's.

Cc: Jamal Hadi Salim <j...@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
---
 net/sched/act_api.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index d09d068..06111aa 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -39,7 +39,7 @@ static void free_tcf(struct rcu_head *head)
 static void tcf_hash_destroy(struct tcf_hashinfo *hinfo, struct tc_action *p)
 {
        spin_lock_bh(&hinfo->lock);
-       hlist_del(&p->tcfa_head);
+       hlist_del_rcu(&p->tcfa_head);
        spin_unlock_bh(&hinfo->lock);
        gen_kill_estimator(&p->tcfa_bstats,
                           &p->tcfa_rate_est);
@@ -79,10 +79,10 @@ static int tcf_dump_walker(struct tcf_hashinfo *hinfo, 
struct sk_buff *skb,
        int err = 0, index = -1, i = 0, s_i = 0, n_i = 0;
        struct nlattr *nest;
 
-       spin_lock_bh(&hinfo->lock);
-
        s_i = cb->args[0];
 
+       rcu_read_lock_bh();
+
        for (i = 0; i < (hinfo->hmask + 1); i++) {
                struct hlist_head *head;
                struct tc_action *p;
@@ -110,7 +110,7 @@ static int tcf_dump_walker(struct tcf_hashinfo *hinfo, 
struct sk_buff *skb,
                }
        }
 done:
-       spin_unlock_bh(&hinfo->lock);
+       rcu_read_unlock_bh();
        if (n_i)
                cb->args[0] += n_i;
        return n_i;
@@ -179,12 +179,12 @@ static struct tc_action *tcf_hash_lookup(u32 index, 
struct tcf_hashinfo *hinfo)
        struct tc_action *p = NULL;
        struct hlist_head *head;
 
-       spin_lock_bh(&hinfo->lock);
+       rcu_read_lock_bh();
        head = &hinfo->htab[tcf_hash(index, hinfo->hmask)];
        hlist_for_each_entry_rcu(p, head, tcfa_head)
                if (p->tcfa_index == index)
                        break;
-       spin_unlock_bh(&hinfo->lock);
+       rcu_read_unlock_bh();
 
        return p;
 }
@@ -301,7 +301,7 @@ void tcf_hash_insert(struct tc_action_net *tn, struct 
tc_action *a)
        unsigned int h = tcf_hash(a->tcfa_index, hinfo->hmask);
 
        spin_lock_bh(&hinfo->lock);
-       hlist_add_head(&a->tcfa_head, &hinfo->htab[h]);
+       hlist_add_head_rcu(&a->tcfa_head, &hinfo->htab[h]);
        spin_unlock_bh(&hinfo->lock);
 }
 EXPORT_SYMBOL(tcf_hash_insert);
-- 
2.1.0