Message ID | 5020F5C3.8010107@parallels.com |
---|---|
State | Changes Requested, archived |
Delegated to: | David Miller |
Headers | show |
On Tue, 2012-08-07 at 15:02 +0400, Pavel Emelyanov wrote: > 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. > > Signed-off-by: Pavel Emelyanov <xemul@parallels.com> > --- > include/net/net_namespace.h | 1 + > net/core/dev.c | 4 ++-- > 2 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h > index ae1cd6c..c5fbebf 100644 > --- a/include/net/net_namespace.h > +++ b/include/net/net_namespace.h > @@ -62,6 +62,7 @@ struct net { > struct sock *rtnl; /* rtnetlink socket */ > struct sock *genl_sock; > > + int ifindex; could you place ifindex right after dev_base_seq : avoid two holes and use the same cache line, dirtied in list_netdevice()/unlist_netdevice() > struct list_head dev_base_head; > struct hlist_head *dev_name_head; > struct hlist_head *dev_index_head; > 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 @@ int dev_ioctl(struct net *net, unsigned int cmd, void __user *arg) > */ > 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; > } > } > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h index ae1cd6c..c5fbebf 100644 --- a/include/net/net_namespace.h +++ b/include/net/net_namespace.h @@ -62,6 +62,7 @@ struct net { struct sock *rtnl; /* rtnetlink socket */ struct sock *genl_sock; + int ifindex; struct list_head dev_base_head; struct hlist_head *dev_name_head; struct hlist_head *dev_index_head; 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 @@ int dev_ioctl(struct net *net, unsigned int cmd, void __user *arg) */ 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; } }
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. Signed-off-by: Pavel Emelyanov <xemul@parallels.com> --- include/net/net_namespace.h | 1 + net/core/dev.c | 4 ++-- 2 files changed, 3 insertions(+), 2 deletions(-)