[PATCH net-next] net/sched: act_tunnel_key: Remove rcu_read_lock protection

[PATCH net-next] net/sched: act_tunnel_key: Remove rcu_read_lock protection

[Hadar Hen Zion]

Remove rcu_read_lock protection from tunnel_key_dump and use
rtnl_dereference, dump operation is protected by  rtnl lock.

Also, remove rcu_read_lock from tunnel_key_release and use
rcu_dereference_protected.

Both operations are running exclusively and a writer couldn't modify
t->params while those functions are executed.

Fixes: 54d94fd89d90 ('net/sched: Introduce act_tunnel_key')
Signed-off-by: Hadar Hen Zion <hadarh@mellanox.com>
---
 net/sched/act_tunnel_key.c | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/net/sched/act_tunnel_key.c b/net/sched/act_tunnel_key.c
index dceff74..af47bdf 100644
--- a/net/sched/act_tunnel_key.c
+++ b/net/sched/act_tunnel_key.c
@@ -194,15 +194,12 @@ static void tunnel_key_release(struct tc_action *a, int bind)
 	struct tcf_tunnel_key *t = to_tunnel_key(a);
 	struct tcf_tunnel_key_params *params;
 
-	rcu_read_lock();
-	params = rcu_dereference(t->params);
+	params = rcu_dereference_protected(t->params, 1);
 
 	if (params->tcft_action == TCA_TUNNEL_KEY_ACT_SET)
 		dst_release(&params->tcft_enc_metadata->dst);
 
 	kfree_rcu(params, rcu);
-
-	rcu_read_unlock();
 }
 
 static int tunnel_key_dump_addresses(struct sk_buff *skb,
@@ -245,10 +242,8 @@ static int tunnel_key_dump(struct sk_buff *skb, struct tc_action *a,
 		.bindcnt  = t->tcf_bindcnt - bind,
 	};
 	struct tcf_t tm;
-	int ret = -1;
 
-	rcu_read_lock();
-	params = rcu_dereference(t->params);
+	params = rtnl_dereference(t->params);
 
 	opt.t_action = params->tcft_action;
 	opt.action = params->action;
@@ -272,15 +267,11 @@ static int tunnel_key_dump(struct sk_buff *skb, struct tc_action *a,
 			  &tm, TCA_TUNNEL_KEY_PAD))
 		goto nla_put_failure;
 
-	ret = skb->len;
-	goto out;
+	return skb->len;
 
 nla_put_failure:
 	nlmsg_trim(skb, b);
-out:
-	rcu_read_unlock();
-
-	return ret;
+	return -1;
 }
 
 static int tunnel_key_walker(struct net *net, struct sk_buff *skb,
-- 
1.8.3.1

Re: [PATCH net-next] net/sched: act_tunnel_key: Remove rcu_read_lock protection

[John Fastabend]

On 16-09-12 05:19 AM, Hadar Hen Zion wrote:
> Remove rcu_read_lock protection from tunnel_key_dump and use
> rtnl_dereference, dump operation is protected by  rtnl lock.
> 
> Also, remove rcu_read_lock from tunnel_key_release and use
> rcu_dereference_protected.
> 
> Both operations are running exclusively and a writer couldn't modify
> t->params while those functions are executed.
> 
> Fixes: 54d94fd89d90 ('net/sched: Introduce act_tunnel_key')
> Signed-off-by: Hadar Hen Zion <hadarh@mellanox.com>
> ---

Thanks for cleaning this up.

Acked-by: John Fastabend <john.r.fastabend@intel.com>

Re: [PATCH net-next] net/sched: act_tunnel_key: Remove rcu_read_lock protection

[Eric Dumazet]

On Mon, 2016-09-12 at 07:09 -0700, John Fastabend wrote:
> On 16-09-12 05:19 AM, Hadar Hen Zion wrote:
> > Remove rcu_read_lock protection from tunnel_key_dump and use
> > rtnl_dereference, dump operation is protected by  rtnl lock.
> > 
> > Also, remove rcu_read_lock from tunnel_key_release and use
> > rcu_dereference_protected.
> > 
> > Both operations are running exclusively and a writer couldn't modify
> > t->params while those functions are executed.
> > 
> > Fixes: 54d94fd89d90 ('net/sched: Introduce act_tunnel_key')
> > Signed-off-by: Hadar Hen Zion <hadarh@mellanox.com>
> > ---
> 
> Thanks for cleaning this up.
> 
> Acked-by: John Fastabend <john.r.fastabend@intel.com>

Exactly, we now have a nice canonical net/sched/act_... component.

Acked-by: Eric Dumazet <edumazet@google.com>

Thanks guys.

Re: [PATCH net-next] net/sched: act_tunnel_key: Remove rcu_read_lock protection

[David Miller]

From: Hadar Hen Zion <hadarh@mellanox.com>
Date: Mon, 12 Sep 2016 15:19:21 +0300

> Remove rcu_read_lock protection from tunnel_key_dump and use
> rtnl_dereference, dump operation is protected by  rtnl lock.
> 
> Also, remove rcu_read_lock from tunnel_key_release and use
> rcu_dereference_protected.
> 
> Both operations are running exclusively and a writer couldn't modify
> t->params while those functions are executed.
> 
> Fixes: 54d94fd89d90 ('net/sched: Introduce act_tunnel_key')
> Signed-off-by: Hadar Hen Zion <hadarh@mellanox.com>

Applied.