Re: [PATCH net-next 2/2] bonding: make hard-coded defines configurable at build

On Tue, Jul 15, 2014 at 9:18 AM, Veaceslav Falico [off-list ref] wrote:

On Tue, Jul 15, 2014 at 08:48:01AM -0700, Alexei Starovoitov wrote:

quoted

On Tue, Jul 15, 2014 at 3:15 AM, Veaceslav Falico [off-list ref]
wrote:

quoted

+
+config BOND_MAX_VLAN_ENCAP
+       int "Maximum number of stacked vlans on top of bonding"
+       default "2"
+

I don't think we should allow changing these defaults so easily.
Not a single HW supports 3 vlan tags. There is no standard for it either.
Why you would ever change this?

There have been discussions about vlan nestings for bonding, and the
outcome was that more than 2 are possible. Also, iirc, no standard limits
it to only 2.

standard doesn't say that the maximum is 2, but it doesn't specify what
should be done in such case, so all vlan-aware switches that I know will
be just dropping packets with 3 vlans.
Therefore for bond driver there is no reason to accept such packets
in the first place from user space, since they won't go too far in the network.

These defaults are scalable by their nature, and there are people
maintaining their own patches to change them. So making them available to
be configured at compile time is a good thing to do, I think.

people keep a patch to support 3 vlans? what's the use case?