Em 25-08-2015 14:35, John Nielsen escreveu:
After updating the kernel on a KVM host, I discovered yesterday that I can no
longer use more than one vxlan interface on a single multicast group/address.
The interfaces can be created but only the first one may be brought up:
# ip link add vx100 type vxlan id 100 group 239.0.0.1 dev eth0
# ip link add vx200 type vxlan id 200 group 239.0.0.1 dev eth0
# ip link set up dev vx100
# ip link set up dev vx200
RTNETLINK answers: Address already in use
Using unique group addresses (one VNI per group) still works as expected. The
problem is not present in kernel 4.0.5 but it is in kernel 4.1.0.
I suspect (but have not verified) that the regression was caused by this commit:
vxlan: Move socket initialization to within rtnl scope
56ef9c909b40483d2c8cb63fcbf83865f162d5ec
https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/drivers/net/vxlan.c?id=56ef9c909b40483d2c8cb63fcbf83865f162d5ec
I am working to verify that that is the culprit but I thought I’d see in the
mean time if anyone else has encountered and/or fixed this, or can at least
shed more light on the problem.
Yes that commit is the culprit. Previously it was ignoring igmp_join
errors, and now it's not but at the same time, it's trying to double
join that group on the socket that is reused.
Will try to cook a patch here, thanks for the report!
If you need a hack for now, just ignore vxlan_igmp_join() return value
at vxlan_open() and it should be fine.
Marcelo
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