[ovs-dev] [PATCH] cfm: Implement "demand mode".

[Ben Pfaff]

On Mon, May 20, 2013 at 03:57:56PM -0700, Ethan Jackson wrote:
> The new CFM "demand mode" (named after BFD's demand mode) uses
> data traffic to indicate interface liveness.  It's helpful on
> heavily congested networks where CCMs may be dropped.
> 
> Signed-off-by: Ethan Jackson <ethan at nicira.com>

Ugh, another CFM extension.  At least the end is in sight now that BFD
is in-tree.

Shall we add a NEWS entry?

The implementation is straightforward and seems correct to me.

I'm nervous about having cfm mess with a netdev owned by the
higher-level module.  Similar tricks caused hard-to-find bugs in the
past.  I sent out a commit to add a "netdev_ref()" function that would
allow cfm to own its own netdev reference instead.

Looking at cfm_configure(), I don't see any way that cfm->demand can
ever be set to false, if it is once set to true.