[net-next,v2,11/15] net: sched: act_vlan: remove dependency on rtnl lock

Message ID 1533923515-5664-12-git-send-email-vladbu@mellanox.com
State Accepted
Delegated to: David Miller
Headers show
Series
  • Remove rtnl lock dependency from all action implementations
Related show

Commit Message

Vlad Buslov Aug. 10, 2018, 5:51 p.m.
Use tcf spinlock to protect vlan action private data from concurrent
modification during dump and init. Use rcu swap operation to reassign
params pointer under protection of tcf lock. (old params value is not used
by init, so there is no need of standalone rcu dereference step)

Remove rtnl assertion that is no longer necessary.

Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
---
 net/sched/act_vlan.c | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

Patch

diff --git a/net/sched/act_vlan.c b/net/sched/act_vlan.c
index 15a0ee214c9c..5bde17fe3608 100644
--- a/net/sched/act_vlan.c
+++ b/net/sched/act_vlan.c
@@ -109,7 +109,7 @@  static int tcf_vlan_init(struct net *net, struct nlattr *nla,
 {
 	struct tc_action_net *tn = net_generic(net, vlan_net_id);
 	struct nlattr *tb[TCA_VLAN_MAX + 1];
-	struct tcf_vlan_params *p, *p_old;
+	struct tcf_vlan_params *p;
 	struct tc_vlan *parm;
 	struct tcf_vlan *v;
 	int action;
@@ -202,26 +202,24 @@  static int tcf_vlan_init(struct net *net, struct nlattr *nla,
 
 	v = to_vlan(*a);
 
-	ASSERT_RTNL();
 	p = kzalloc(sizeof(*p), GFP_KERNEL);
 	if (!p) {
 		tcf_idr_release(*a, bind);
 		return -ENOMEM;
 	}
 
-	v->tcf_action = parm->action;
-
-	p_old = rtnl_dereference(v->vlan_p);
-
 	p->tcfv_action = action;
 	p->tcfv_push_vid = push_vid;
 	p->tcfv_push_prio = push_prio;
 	p->tcfv_push_proto = push_proto;
 
-	rcu_assign_pointer(v->vlan_p, p);
+	spin_lock(&v->tcf_lock);
+	v->tcf_action = parm->action;
+	rcu_swap_protected(v->vlan_p, p, lockdep_is_held(&v->tcf_lock));
+	spin_unlock(&v->tcf_lock);
 
-	if (p_old)
-		kfree_rcu(p_old, rcu);
+	if (p)
+		kfree_rcu(p, rcu);
 
 	if (ret == ACT_P_CREATED)
 		tcf_idr_insert(tn, *a);
@@ -243,16 +241,18 @@  static int tcf_vlan_dump(struct sk_buff *skb, struct tc_action *a,
 {
 	unsigned char *b = skb_tail_pointer(skb);
 	struct tcf_vlan *v = to_vlan(a);
-	struct tcf_vlan_params *p = rtnl_dereference(v->vlan_p);
+	struct tcf_vlan_params *p;
 	struct tc_vlan opt = {
 		.index    = v->tcf_index,
 		.refcnt   = refcount_read(&v->tcf_refcnt) - ref,
 		.bindcnt  = atomic_read(&v->tcf_bindcnt) - bind,
-		.action   = v->tcf_action,
-		.v_action = p->tcfv_action,
 	};
 	struct tcf_t t;
 
+	spin_lock(&v->tcf_lock);
+	opt.action = v->tcf_action;
+	p = rcu_dereference_protected(v->vlan_p, lockdep_is_held(&v->tcf_lock));
+	opt.v_action = p->tcfv_action;
 	if (nla_put(skb, TCA_VLAN_PARMS, sizeof(opt), &opt))
 		goto nla_put_failure;
 
@@ -268,9 +268,12 @@  static int tcf_vlan_dump(struct sk_buff *skb, struct tc_action *a,
 	tcf_tm_dump(&t, &v->tcf_tm);
 	if (nla_put_64bit(skb, TCA_VLAN_TM, sizeof(t), &t, TCA_VLAN_PAD))
 		goto nla_put_failure;
+	spin_unlock(&v->tcf_lock);
+
 	return skb->len;
 
 nla_put_failure:
+	spin_unlock(&v->tcf_lock);
 	nlmsg_trim(skb, b);
 	return -1;
 }