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[NETNS]: The net-subsys IDs generator.

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To make some per-net generic pointers, we need some way to address
them, i.e. - IDs. This is simple IDA-based IDs generator for pernet
subsystems.

Addressing questions about potential checkpoint/restart problems: 
these IDs are "lite-offsets" within the net structure and are by no 
means supposed to be exported to the userspace.

Since it will be used in the nearest future by devices only (tun,
vlan, tunnels, bridge, etc), I make it resemble the functionality
of register_pernet_device().

The new ids is stored in the *id pointer _before_ calling the init
callback to make this id available in this callback.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Pavel Emelyanov 2008-04-15 00:35:23 -07:00 committed by David S. Miller
parent 31efdf0530
commit c93cf61fd1
2 changed files with 40 additions and 0 deletions
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2
include/net/net_namespace.h
View File

@ -185,6 +185,8 @@ 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 *);
extern int register_pernet_gen_device(int *id, struct pernet_operations *);
extern void unregister_pernet_gen_device(int id, struct pernet_operations *);
struct ctl_path;
struct ctl_table;

38
net/core/net_namespace.c
View File

@ -5,6 +5,7 @@
#include <linux/list.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/idr.h>
#include <net/net_namespace.h>
/*
@ -253,6 +254,8 @@ static void unregister_pernet_operations(struct pernet_operations *ops)
}
#endif
static DEFINE_IDA(net_generic_ids);
/**
* register_pernet_subsys - register a network namespace subsystem
* @ops: pernet operations structure for the subsystem
@ -330,6 +333,30 @@ int register_pernet_device(struct pernet_operations *ops)
}
EXPORT_SYMBOL_GPL(register_pernet_device);
int register_pernet_gen_device(int *id, struct pernet_operations *ops)
{
int error;
mutex_lock(&net_mutex);
again:
error = ida_get_new_above(&net_generic_ids, 1, id);
if (error) {
if (error == -EAGAIN) {
ida_pre_get(&net_generic_ids, GFP_KERNEL);
goto again;
}
goto out;
}
error = register_pernet_operations(&pernet_list, ops);
if (error)
ida_remove(&net_generic_ids, *id);
else if (first_device == &pernet_list)
first_device = &ops->list;
out:
mutex_unlock(&net_mutex);
return error;
}
EXPORT_SYMBOL_GPL(register_pernet_gen_device);
/**
* unregister_pernet_device - unregister a network namespace netdevice
* @ops: pernet operations structure to manipulate
@ -348,3 +375,14 @@ void unregister_pernet_device(struct pernet_operations *ops)
mutex_unlock(&net_mutex);
}
EXPORT_SYMBOL_GPL(unregister_pernet_device);
void unregister_pernet_gen_device(int id, struct pernet_operations *ops)
{
mutex_lock(&net_mutex);
if (&ops->list == first_device)
first_device = first_device->next;
unregister_pernet_operations(ops);
ida_remove(&net_generic_ids, id);
mutex_unlock(&net_mutex);
}
EXPORT_SYMBOL_GPL(unregister_pernet_gen_device);