[ovs-git] [openvswitch/ovs] 59d18a: ovs-ctl: Don't remember vport-* kernel modules

[GitHub]

  Branch: refs/heads/branch-2.8
  Home:   https://github.com/openvswitch/ovs
  Commit: 59d18a069a10b7bf63ab406650ae7c875ef4d3d3
      https://github.com/openvswitch/ovs/commit/59d18a069a10b7bf63ab406650ae7c875ef4d3d3
  Author: Gurucharan Shetty <guru at ovn.org>
  Date:   2017-11-13 (Mon, 13 Nov 2017)

  Changed paths:
    M utilities/ovs-ctl.in

  Log Message:
  -----------
  ovs-ctl: Don't remember vport-* kernel modules

>From OVS 2.8, ovs-vswitchd, when it starts, will
load the kernel modules for tunnels. It has logic
inside it to choose either upstream kernel module
or vport-* kernel module.

So, when we run 'force-reload-kmod' to upgrade to
OVS 2.8 from a previous version,  we do not need to
remember the vport-* kernel module that was previously
loaded.  It is not really harmful to load vport-* kernel
module though.

On RHEL7.x and OVS 2.8, we use the upstream "geneve" kernel
module for tunnels.

But, on RHEL 7.x we have hit a bug caused by iptables
startup script which tries to remove all kernel modules
related to linux conntrack. It fails to unload openvswitch
kernel module because it has a reference count on it. But it
succeeds in unloading vport-geneve and in turn the upstream
"geneve" kernel module.  This causes the tunnels to go down.

With this patch, we avoid the above situation, by not loading
vport-geneve kernel module.  ovs-vswitchd when it starts will
load upstream geneve. And when "iptables stop" runs, since
"geneve" has nothing to do with conntrack, it spares it.
Ideally, we should fix this by incrementing the refcount
on the kernel modules.

Signed-off-by: Gurucharan Shetty <guru at ovn.org>
Acked-by: William Tu <u9012063 at gmail.com>