net: Make ifindex generation per-net namespace
Strictly speaking this is only _really_ required for checkpoint-restore to
make loopback device always have the same index.
This change appears to be safe wrt "ifindex should be unique per-system"
concept, as all the ifindex usage is either already made per net namespace
of is explicitly limited with init_net only.
There are two cool side effects of this. The first one -- ifindices of
devices in container are always small, regardless of how many containers
we've started (and re-started) so far. The second one is -- we can speed
up the loopback ifidex access as shown in the next patch.
v2: Place ifindex right after dev_base_seq : avoid two holes and use the
same cache line, dirtied in list_netdevice()/unlist_netdevice()
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index 3ca300d..1f06df8 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5221,12 +5221,12 @@
*/
static int dev_new_index(struct net *net)
{
- static int ifindex;
+ int ifindex = net->ifindex;
for (;;) {
if (++ifindex <= 0)
ifindex = 1;
if (!__dev_get_by_index(net, ifindex))
- return ifindex;
+ return net->ifindex = ifindex;
}
}