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Commit 11a28d37 authored by Johannes Berg's avatar Johannes Berg Committed by David S. Miller
Browse files

net: make namespace iteration possible under RCU 



All we need to take care of is using proper RCU list
add/del primitives and inserting a synchronize_rcu()
at one place to make sure the exit notifiers are run
after everybody has stopped iterating the list.

Signed-off-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6c04bb18

include/net/net_namespace.h

+3 −0
Original line number Diff line number Diff line
@@ -208,6 +208,9 @@ static inline struct net *read_pnet(struct net * const *pnet) 
#define for_each_net(VAR)				\

	list_for_each_entry(VAR, &net_namespace_list, list)



#define for_each_net_rcu(VAR)				\

	list_for_each_entry_rcu(VAR, &net_namespace_list, list)



#ifdef CONFIG_NET_NS

#define __net_init

#define __net_exit

net/core/net_namespace.c

+11 −3
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#include <linux/delay.h>

#include <linux/sched.h>

#include <linux/idr.h>

#include <linux/rculist.h>

#include <net/net_namespace.h>

#include <net/netns/generic.h>
@@ -127,7 +128,7 @@ 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 +157,16 @@ 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)
@@ -219,7 +227,7 @@ 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);