[PATCH][NETNS] Make ifindex generation per-namespace [message #21458] |
Tue, 09 October 2007 12:19 |
Pavel Emelianov
Messages: 1149 Registered: September 2006
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Senior Member |
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Currently indexes for netdevices come sequentially one by
one, and the same stays true even for devices that are
created for namespaces.
Side effects of this are:
* lo device has not 1 index in a namespace. This may break
some userspace that relies on it (and AFAIR something
really broke in OpenVZ VEs without this);
* after some time namespaces will have devices with indexes
like 1000000 os similar. This might be confusing for a
human (tools will not mind).
So move the (currently "global" and static) ifindex variable
on the struct net, making the indexes allocation look more
like on a standalone machine.
Moreover - when we have indexes intersect between namespaces,
we may catch more BUGs in the future related to "wrong device
was found for a given index".
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
---
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 93aa87d..83a18d0 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -29,6 +29,8 @@ struct net {
struct list_head dev_base_head;
struct hlist_head *dev_name_head;
struct hlist_head *dev_index_head;
+
+ int ifindex;
};
#ifdef CONFIG_NET
diff --git a/net/core/dev.c b/net/core/dev.c
index e7e728a..a08ed8c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3443,12 +3443,11 @@ int dev_ioctl(struct net *net, unsigned
*/
static int dev_new_index(struct net *net)
{
- static int ifindex;
for (;;) {
- if (++ifindex <= 0)
- ifindex = 1;
- if (!__dev_get_by_index(net, ifindex))
- return ifindex;
+ if (++net->ifindex <= 0)
+ net->ifindex = 1;
+ if (!__dev_get_by_index(net, net->ifindex))
+ return net->ifindex;
}
}
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Re: [PATCH][NETNS] Make ifindex generation per-namespace [message #21590 is a reply to message #21574] |
Thu, 11 October 2007 17:22 |
ebiederm
Messages: 1354 Registered: February 2006
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Senior Member |
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Johannes Berg <johannes@sipsolutions.net> writes:
> On Wed, 2007-10-10 at 13:51 -0600, Eric W. Biederman wrote:
>
>> Yes. Netlink sockets are per-namespace and you can use the namespace
>> of a netlink socket to look up a netdev.
>
> Ok, thanks. I still haven't really looked into the wireless vs. net
> namespaces problem but this will probably help.
I think I may even have some patches in my proof of concept tree that
address some of the wireless issues. Especially rtnetlink ones.
Generally those cases haven't been hard to spot.
Having hash tables and the like that hash and do key compares
on an ifindex instead of a net_device * are the in kernel places that
make it very hard to have duplicate ifindexes.
Thinking about it probably the biggest challenge to deal with
is iff in struct sk_buff.
Eric
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