Eric W. Biederman wrote: > Pavel Emelyanov <[EMAIL PROTECTED]> writes: > >> 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); > > As it happens lo hasn't been registered first for some time > so it hasn't had ifindex of 1 in the normal kernel. > >> * after some time namespaces will have devices with indexes >> like 1000000 os similar. This might be confusing for a >> human (tools will not mind). > > Only if we wind up creating that many devices.
Nope. Create and destroy new net ns for 10000 times and you'll get it. >> 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". > > Not yet. > > I know there are several data structures internal to the kernel that > are indexed by ifindex, and not struct net_device *. There is the > iflink field in struct net_device. We need a way to refer to network > devices in other namespaces in rtnetlink in an unambiguous way. I > don't see any real problems with a global ifindex assignment until > we start migrating applications. > > So please hold off on this until the kernel has been audited and > we have removed all of the uses of ifindex that assume ifindex is > global, that we can find. Ok. > Right now a namespace local ifindex seems to be just asking for > trouble. You said the same about caching the global pid on the task_struct, but looks like you were wrong ;) Just kidding. > Eric > > - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
