Merge branch 'vlan_features'

Michal Kubecek says:

====================
net: device features handling fixes

> I think we need to think more about what exact behavior is desired in
> mixed csum feature set cases.  Probably whatever csum offload type is
> the most prevelant should be the one advertised by the master.  It
> means we will do that software checksum fixup for the oddball slaves,
> but it seems the best we can do.

I've been thinking about it some more and I believe what I proposed is
correct: features that are or-ed (ONE_FOR_ALL) should start with 0,
those which are and-ed (ALL_FOR_ALL) with 1.

But once we do that, we have to fix another problem in vlan module:
features of a vlan device are mostly computed as bitwise AND of features
and vlan_features of its underlying device. The problem is checksumming
features don't really behave like independent flags as their main
purpose is to be used in can_checksum_protocol() whose logic is that
HW_CSUM (GEN_CSUM) means "can checksum everything" so that it kind of
contains IP(V6)_CSUM functionality. Therefore intersection of HW_CSUM
and IP(V6)_CSUM should result in the latter.

An alternative approach would be to always set IP(V6)_CSUM once HW_CSUM
(any of GEN_CSUM) is set but as for long time people were taught not to
do that and we even have a warning for it, switching to the exact
opposite could cause a lot of problems.

> Also, like Jay, I agree that whatever we do in bonding needs to be
> done in team too and I'd like the bug fixed at the same time in both
> places.

Agreed. Added a similar patch for teaming driver.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 0 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 2dea98cbbdba..f4ad247fd324 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3153,6 +3153,20 @@ const char *netdev_drivername(const struct net_device *dev);
 
 void linkwatch_run_queue(void);
 
+static inline netdev_features_t netdev_intersect_features(netdev_features_t f1,
+							  netdev_features_t f2)
+{
+	if (f1 & NETIF_F_GEN_CSUM)
+		f1 |= (NETIF_F_ALL_CSUM & ~NETIF_F_GEN_CSUM);
+	if (f2 & NETIF_F_GEN_CSUM)
+		f2 |= (NETIF_F_ALL_CSUM & ~NETIF_F_GEN_CSUM);
+	f1 &= f2;
+	if (f1 & NETIF_F_GEN_CSUM)
+		f1 &= ~(NETIF_F_ALL_CSUM & ~NETIF_F_GEN_CSUM);
+
+	return f1;
+}
+
 static inline netdev_features_t netdev_get_wanted_features(
 	struct net_device *dev)
 {