[PATCH 07/30] netns: extract net_create()

[PATCH 07/30] netns: extract net_create()

[Alexey Dobriyan]

net_create() will be used by C/R code to create fresh netns on restart.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---

 include/net/net_namespace.h |    1 +
 net/core/net_namespace.c    |   44 ++++++++++++++++++++------------------------
 2 files changed, 21 insertions(+), 24 deletions(-)

--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -107,6 +107,7 @@ static inline struct net *copy_net_ns(unsigned long flags, struct net *net_ns)
 extern struct list_head net_namespace_list;
 
 #ifdef CONFIG_NET_NS
+struct net *net_create(void);
 extern void __put_net(struct net *net);
 
 static inline struct net *get_net(struct net *net)
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -115,38 +115,34 @@ static void net_free(struct net *net)
 	kmem_cache_free(net_cachep, net);
 }
 
-struct net *copy_net_ns(unsigned long flags, struct net *old_net)
+struct net *net_create(void)
 {
-	struct net *new_net = NULL;
-	int err;
-
-	if (!(flags & CLONE_NEWNET))
-		return get_net(old_net);
-
-	err = -ENOMEM;
-	new_net = net_alloc();
-	if (!new_net)
-		goto out_err;
+	struct net *net;
+	int rv;
 
+	net = net_alloc();
+	if (!net)
+		return ERR_PTR(-ENOMEM);
 	mutex_lock(&net_mutex);
-	err = setup_net(new_net);
-	if (!err) {
+	rv = setup_net(net);
+	if (rv == 0) {
 		rtnl_lock();
-		list_add_tail(&new_net->list, &net_namespace_list);
+		list_add_tail(&net->list, &net_namespace_list);
 		rtnl_unlock();
 	}
 	mutex_unlock(&net_mutex);
+	if (rv < 0) {
+		net_free(net);
+		return ERR_PTR(rv);
+	}
+	return net;
+}
 
-	if (err)
-		goto out_free;
-out:
-	return new_net;
-
-out_free:
-	net_free(new_net);
-out_err:
-	new_net = ERR_PTR(err);
-	goto out;
+struct net *copy_net_ns(unsigned long flags, struct net *old_net)
+{
+	if (!(flags & CLONE_NEWNET))
+		return get_net(old_net);
+	return net_create();
 }
 
 static void cleanup_net(struct work_struct *work)

Re: [PATCH 07/30] netns: extract net_create()

[Ingo Molnar]

* Alexey Dobriyan <adobriyan@gmail.com> wrote:

> --- a/include/net/net_namespace.h
> +++ b/include/net/net_namespace.h
> @@ -107,6 +107,7 @@ static inline struct net *copy_net_ns(unsigned long flags, struct net *net_ns)
>  extern struct list_head net_namespace_list;
>  
>  #ifdef CONFIG_NET_NS
> +struct net *net_create(void);
>  extern void __put_net(struct net *net);

Ditto.

	Ingo

Re: [PATCH 07/30] netns: extract net_create()

[Serge E. Hallyn]

Quoting Alexey Dobriyan (adobriyan@gmail.com):
> net_create() will be used by C/R code to create fresh netns on restart.
> 
> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>

Acked-by: Serge Hallyn <serue@us.ibm.com>

Although this ends up making a new assumption that setup_net(), and
therefore the pernet_ops->init() functions, do not return error > 0.
There's nothing actually stopping that (outside of code review, but
there appears to be no comment anywhere saying that's uncooth).

If it returns > 0, then we return the ns as though it were valid, but
don't add it to the list of namespaces...  Do we care?

-serge

> ---
> 
>  include/net/net_namespace.h |    1 +
>  net/core/net_namespace.c    |   44 ++++++++++++++++++++------------------------
>  2 files changed, 21 insertions(+), 24 deletions(-)
> 
> --- a/include/net/net_namespace.h
> +++ b/include/net/net_namespace.h
> @@ -107,6 +107,7 @@ static inline struct net *copy_net_ns(unsigned long flags, struct net *net_ns)
>  extern struct list_head net_namespace_list;
> 
>  #ifdef CONFIG_NET_NS
> +struct net *net_create(void);
>  extern void __put_net(struct net *net);
> 
>  static inline struct net *get_net(struct net *net)
> --- a/net/core/net_namespace.c
> +++ b/net/core/net_namespace.c
> @@ -115,38 +115,34 @@ static void net_free(struct net *net)
>  	kmem_cache_free(net_cachep, net);
>  }
> 
> -struct net *copy_net_ns(unsigned long flags, struct net *old_net)
> +struct net *net_create(void)
>  {
> -	struct net *new_net = NULL;
> -	int err;
> -
> -	if (!(flags & CLONE_NEWNET))
> -		return get_net(old_net);
> -
> -	err = -ENOMEM;
> -	new_net = net_alloc();
> -	if (!new_net)
> -		goto out_err;
> +	struct net *net;
> +	int rv;
> 
> +	net = net_alloc();
> +	if (!net)
> +		return ERR_PTR(-ENOMEM);
>  	mutex_lock(&net_mutex);
> -	err = setup_net(new_net);
> -	if (!err) {
> +	rv = setup_net(net);
> +	if (rv == 0) {
>  		rtnl_lock();
> -		list_add_tail(&new_net->list, &net_namespace_list);
> +		list_add_tail(&net->list, &net_namespace_list);
>  		rtnl_unlock();
>  	}
>  	mutex_unlock(&net_mutex);
> +	if (rv < 0) {
> +		net_free(net);
> +		return ERR_PTR(rv);
> +	}
> +	return net;
> +}
> 
> -	if (err)
> -		goto out_free;
> -out:
> -	return new_net;
> -
> -out_free:
> -	net_free(new_net);
> -out_err:
> -	new_net = ERR_PTR(err);
> -	goto out;
> +struct net *copy_net_ns(unsigned long flags, struct net *old_net)
> +{
> +	if (!(flags & CLONE_NEWNET))
> +		return get_net(old_net);
> +	return net_create();
>  }
> 
>  static void cleanup_net(struct work_struct *work)

Re: [PATCH 07/30] netns: extract net_create()

[Alexey Dobriyan]

On Fri, Apr 10, 2009 at 05:56:36PM -0500, Serge E. Hallyn wrote:
> Quoting Alexey Dobriyan (adobriyan@gmail.com):
> > net_create() will be used by C/R code to create fresh netns on restart.
> > 
> > Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
> 
> Acked-by: Serge Hallyn <serue@us.ibm.com>
> 
> Although this ends up making a new assumption that setup_net(), and
> therefore the pernet_ops->init() functions, do not return error > 0.
> There's nothing actually stopping that (outside of code review, but
> there appears to be no comment anywhere saying that's uncooth).
> 
> If it returns > 0, then we return the ns as though it were valid, but
> don't add it to the list of namespaces...  Do we care?

I think, no.

Recalling all the code put under netns changes, ->init hooks were put
under 0/-E convention. For sure, my changes in netns xtables,
conntracking and xfrm were definitely under it.

> > -struct net *copy_net_ns(unsigned long flags, struct net *old_net)
> > +struct net *net_create(void)