net: move and export get_net_ns_by_pid

[safe/jmp/linux-2.6] / net / core / net_namespace.c

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index b7292a2..ddd2cd2 100644 (file)
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -6,6 +6,8 @@
 #include <linux/delay.h>
 #include <linux/sched.h>
 #include <linux/idr.h>
+#include <linux/rculist.h>
+#include <linux/nsproxy.h>
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
 
@@ -127,7 +129,7 @@ static struct net *net_create(void)
        rv = setup_net(net);
        if (rv == 0) {
                rtnl_lock();
-               list_add_tail(&net->list, &net_namespace_list);
+               list_add_tail_rcu(&net->list, &net_namespace_list);
                rtnl_unlock();
        }
        mutex_unlock(&net_mutex);
@@ -156,9 +158,16 @@ static void cleanup_net(struct work_struct *work)
 
        /* Don't let anyone else find us. */
        rtnl_lock();
-       list_del(&net->list);
+       list_del_rcu(&net->list);
        rtnl_unlock();
 
+       /*
+        * Another CPU might be rcu-iterating the list, wait for it.
+        * This needs to be before calling the exit() notifiers, so
+        * the rcu_barrier() below isn't sufficient alone.
+        */
+       synchronize_rcu();
+
        /* Run all of the network namespace exit methods */
        list_for_each_entry_reverse(ops, &pernet_list, list) {
                if (ops->exit)
@@ -193,6 +202,26 @@ struct net *copy_net_ns(unsigned long flags, struct net *old_net)
 }
 #endif
 
+struct net *get_net_ns_by_pid(pid_t pid)
+{
+       struct task_struct *tsk;
+       struct net *net;
+
+       /* Lookup the network namespace */
+       net = ERR_PTR(-ESRCH);
+       rcu_read_lock();
+       tsk = find_task_by_vpid(pid);
+       if (tsk) {
+               struct nsproxy *nsproxy;
+               nsproxy = task_nsproxy(tsk);
+               if (nsproxy)
+                       net = get_net(nsproxy->net_ns);
+       }
+       rcu_read_unlock();
+       return net;
+}
+EXPORT_SYMBOL_GPL(get_net_ns_by_pid);
+
 static int __init net_ns_init(void)
 {
        struct net_generic *ng;
@@ -219,7 +248,7 @@ static int __init net_ns_init(void)
                panic("Could not setup the initial network namespace");
 
        rtnl_lock();
-       list_add_tail(&init_net.list, &net_namespace_list);
+       list_add_tail_rcu(&init_net.list, &net_namespace_list);
        rtnl_unlock();
 
        mutex_unlock(&net_mutex);