From a6ec437be3d70e9ba85fb34941a96577dcbb8414 Mon Sep 17 00:00:00 2001 From: Vlad Yasevich Date: Tue, 19 Nov 2013 20:47:15 -0500 Subject: [PATCH] net: core: Always propagate flag changes to interfaces [ Upstream commit d2615bf450694c1302d86b9cc8a8958edfe4c3a4 ] The following commit: b6c40d68ff6498b7f63ddf97cf0aa818d748dee7 net: only invoke dev->change_rx_flags when device is UP tried to fix a problem with VLAN devices and promiscuouse flag setting. The issue was that VLAN device was setting a flag on an interface that was down, thus resulting in bad promiscuity count. This commit blocked flag propagation to any device that is currently down. A later commit: deede2fabe24e00bd7e246eb81cd5767dc6fcfc7 vlan: Don't propagate flag changes on down interfaces fixed VLAN code to only propagate flags when the VLAN interface is up, thus fixing the same issue as above, only localized to VLAN. The problem we have now is that if we have create a complex stack involving multiple software devices like bridges, bonds, and vlans, then it is possible that the flags would not propagate properly to the physical devices. A simple examle of the scenario is the following: eth0----> bond0 ----> bridge0 ---> vlan50 If bond0 or eth0 happen to be down at the time bond0 is added to the bridge, then eth0 will never have promisc mode set which is currently required for operation as part of the bridge. As a result, packets with vlan50 will be dropped by the interface. The only 2 devices that implement the special flag handling are VLAN and DSA and they both have required code to prevent incorrect flag propagation. As a result we can remove the generic solution introduced in b6c40d68ff6498b7f63ddf97cf0aa818d748dee7 and leave it to the individual devices to decide whether they will block flag propagation or not. Reported-by: Stefan Priebe Suggested-by: Veaceslav Falico Signed-off-by: Vlad Yasevich Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/core/dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/dev.c b/net/core/dev.c index 2afc521..3d13874 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4815,7 +4815,7 @@ static void dev_change_rx_flags(struct net_device *dev, int flags) { const struct net_device_ops *ops = dev->netdev_ops; - if ((dev->flags & IFF_UP) && ops->ndo_change_rx_flags) + if (ops->ndo_change_rx_flags) ops->ndo_change_rx_flags(dev, flags); } -- 2.7.4