net-core-always-propagate-flag-changes.patch

   1 From d2615bf450694c1302d86b9cc8a8958edfe4c3a4 Mon Sep 17 00:00:00 2001
   2 From: Vlad Yasevich <vyasevic@redhat.com>
   3 Date: Wed, 20 Nov 2013 01:47:15 +0000
   4 Subject: net: core: Always propagate flag changes to interfaces
   5
   6 The following commit:
   7     b6c40d68ff6498b7f63ddf97cf0aa818d748dee7
   8     net: only invoke dev->change_rx_flags when device is UP
   9
  10 tried to fix a problem with VLAN devices and promiscuouse flag setting.
  11 The issue was that VLAN device was setting a flag on an interface that
  12 was down, thus resulting in bad promiscuity count.
  13 This commit blocked flag propagation to any device that is currently
  14 down.
  15
  16 A later commit:
  17     deede2fabe24e00bd7e246eb81cd5767dc6fcfc7
  18     vlan: Don't propagate flag changes on down interfaces
  19
  20 fixed VLAN code to only propagate flags when the VLAN interface is up,
  21 thus fixing the same issue as above, only localized to VLAN.
  22
  23 The problem we have now is that if we have create a complex stack
  24 involving multiple software devices like bridges, bonds, and vlans,
  25 then it is possible that the flags would not propagate properly to
  26 the physical devices.  A simple examle of the scenario is the
  27 following:
  28
  29   eth0----> bond0 ----> bridge0 ---> vlan50
  30
  31 If bond0 or eth0 happen to be down at the time bond0 is added to
  32 the bridge, then eth0 will never have promisc mode set which is
  33 currently required for operation as part of the bridge.  As a
  34 result, packets with vlan50 will be dropped by the interface.
  35
  36 The only 2 devices that implement the special flag handling are
  37 VLAN and DSA and they both have required code to prevent incorrect
  38 flag propagation.  As a result we can remove the generic solution
  39 introduced in b6c40d68ff6498b7f63ddf97cf0aa818d748dee7 and leave
  40 it to the individual devices to decide whether they will block
  41 flag propagation or not.
  42
  43 Reported-by: Stefan Priebe <s.priebe@profihost.ag>
  44 Suggested-by: Veaceslav Falico <vfalico@redhat.com>
  45 Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
  46 Signed-off-by: David S. Miller <davem@davemloft.net>
  47 ---
  48 (limited to 'net/core/dev.c')
  49
  50 diff --git a/net/core/dev.c b/net/core/dev.c
  51 index 7e00a73..ba3b7ea 100644
  52 --- a/net/core/dev.c
  53 +++ b/net/core/dev.c
  54 @@ -4996,7 +4996,7 @@ static void dev_change_rx_flags(struct net_device *dev, int flags)
  55  {
  56         const struct net_device_ops *ops = dev->netdev_ops;
  57
  58 -       if ((dev->flags & IFF_UP) && ops->ndo_change_rx_flags)
  59 +       if (ops->ndo_change_rx_flags)
  60                 ops->ndo_change_rx_flags(dev, flags);
  61  }
  62
  63 --
  64 cgit v0.9.2