android_kernel_xiaomi_sm8350/include/net/net_namespace.h
Eric W. Biederman f4618d39a3 [NETNS]: Simplify the network namespace list locking rules.
Denis V. Lunev <den@sw.ru> noticed that the locking rules
for the network namespace list are over complicated and broken.

In particular the current register_netdev_notifier currently
does not take any lock making the for_each_net iteration racy
with network namespace creation and destruction. Oops.

The fact that we need to use for_each_net in rtnl_unlock() when
the rtnetlink support becomes per network namespace makes designing
the proper locking tricky.  In addition we need to be able to call
rtnl_lock() and rtnl_unlock() when we have the net_mutex held.

After thinking about it and looking at the alternatives carefully
it looks like the simplest and most maintainable solution is
to remove net_list_mutex altogether, and to use the rtnl_mutex instead.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:52:55 -07:00

115 lines
2.6 KiB
C

/*
* Operations on the network namespace
*/
#ifndef __NET_NET_NAMESPACE_H
#define __NET_NET_NAMESPACE_H
#include <asm/atomic.h>
#include <linux/workqueue.h>
#include <linux/list.h>
struct proc_dir_entry;
struct net_device;
struct net {
atomic_t count; /* To decided when the network
* namespace should be freed.
*/
atomic_t use_count; /* To track references we
* destroy on demand
*/
struct list_head list; /* list of network namespaces */
struct work_struct work; /* work struct for freeing */
struct proc_dir_entry *proc_net;
struct proc_dir_entry *proc_net_stat;
struct proc_dir_entry *proc_net_root;
struct net_device *loopback_dev; /* The loopback */
struct list_head dev_base_head;
struct hlist_head *dev_name_head;
struct hlist_head *dev_index_head;
};
#ifdef CONFIG_NET
/* Init's network namespace */
extern struct net init_net;
#define INIT_NET_NS(net_ns) .net_ns = &init_net,
#else
#define INIT_NET_NS(net_ns)
#endif
extern struct list_head net_namespace_list;
#ifdef CONFIG_NET
extern struct net *copy_net_ns(unsigned long flags, struct net *net_ns);
#else
static inline struct net *copy_net_ns(unsigned long flags, struct net *net_ns)
{
/* There is nothing to copy so this is a noop */
return net_ns;
}
#endif
extern void __put_net(struct net *net);
static inline struct net *get_net(struct net *net)
{
#ifdef CONFIG_NET
atomic_inc(&net->count);
#endif
return net;
}
static inline struct net *maybe_get_net(struct net *net)
{
/* Used when we know struct net exists but we
* aren't guaranteed a previous reference count
* exists. If the reference count is zero this
* function fails and returns NULL.
*/
if (!atomic_inc_not_zero(&net->count))
net = NULL;
return net;
}
static inline void put_net(struct net *net)
{
#ifdef CONFIG_NET
if (atomic_dec_and_test(&net->count))
__put_net(net);
#endif
}
static inline struct net *hold_net(struct net *net)
{
#ifdef CONFIG_NET
atomic_inc(&net->use_count);
#endif
return net;
}
static inline void release_net(struct net *net)
{
#ifdef CONFIG_NET
atomic_dec(&net->use_count);
#endif
}
#define for_each_net(VAR) \
list_for_each_entry(VAR, &net_namespace_list, list)
struct pernet_operations {
struct list_head list;
int (*init)(struct net *net);
void (*exit)(struct net *net);
};
extern int register_pernet_subsys(struct pernet_operations *);
extern void unregister_pernet_subsys(struct pernet_operations *);
extern int register_pernet_device(struct pernet_operations *);
extern void unregister_pernet_device(struct pernet_operations *);
#endif /* __NET_NET_NAMESPACE_H */