[PATCH] netlink: switch net_ns only if net is not init_net

[PATCH] netlink: switch net_ns only if net is not init_net

[Gu Zheng]

Many netlink users create netlink sock in the init_net, and the
switching nes_ns(init_net-->net) is needless in this case. So here
we add a pre-check to avoid this.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
---
 net/netlink/af_netlink.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index fdf5135..e9e4be9 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2429,7 +2429,8 @@ __netlink_kernel_create(struct net *net, int unit, struct module *module,
 		goto out_sock_release_nosk;
 
 	sk = sock->sk;
-	sk_change_net(sk, net);
+	if (!net_eq(net, &init_net))
+		sk_change_net(sk, net);
 
 	if (!cfg || cfg->groups < 32)
 		groups = 32;
-- 
1.7.7

Re: [PATCH] netlink: switch net_ns only if net is not init_net

[David Miller]

From: Gu Zheng <guz.fnst@cn.fujitsu.com>
Date: Fri, 07 Mar 2014 18:47:30 +0800

> Many netlink users create netlink sock in the init_net, and the
> switching nes_ns(init_net-->net) is needless in this case. So here
> we add a pre-check to avoid this.
> 
> Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>

This check is more appropriately placed into sk_change_net() itself.

Re: [PATCH] netlink: switch net_ns only if net is not init_net

[Gu Zheng]

On 03/10/2014 07:09 AM, David Miller wrote:

> From: Gu Zheng <guz.fnst@cn.fujitsu.com>
> Date: Fri, 07 Mar 2014 18:47:30 +0800
> 
>> Many netlink users create netlink sock in the init_net, and the
>> switching nes_ns(init_net-->net) is needless in this case. So here
>> we add a pre-check to avoid this.
>>
>> Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
> 
> This check is more appropriately placed into sk_change_net() itself.

Agree. I'll update it soon.

Regards,
Gu

> 

[PATCH] net: add a pre-check of net_ns in sk_change_net()

[Gu Zheng]

We do not need to switch the net_ns if the target net_ns the same
as the current one, so here we add a pre-check of net_ns to avoid
this as David suggested.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
---
 include/net/sock.h |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 5c3f7c3..9678569 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2252,8 +2252,12 @@ void sock_net_set(struct sock *sk, struct net *net)
  */
 static inline void sk_change_net(struct sock *sk, struct net *net)
 {
-	put_net(sock_net(sk));
-	sock_net_set(sk, hold_net(net));
+	struct net *current_net = sock_net(sk);
+
+	if (!net_eq(current_net, net)) {
+		put_net(current_net);
+		sock_net_set(sk, hold_net(net));
+	}
 }
 
 static inline struct sock *skb_steal_sock(struct sk_buff *skb)
-- 
1.7.7

Re: [PATCH] net: add a pre-check of net_ns in sk_change_net()

[David Miller]

From: Gu Zheng <guz.fnst@cn.fujitsu.com>
Date: Mon, 10 Mar 2014 09:57:34 +0800

> We do not need to switch the net_ns if the target net_ns the same
> as the current one, so here we add a pre-check of net_ns to avoid
> this as David suggested.
> 
> Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>

Applied to net-next, thank you.