It is not enough to set ifnet->if_mtu to change the interface MTU. System saves the MTU for route in the radix tree, and route cache keeps the interface MTU as well. Since addition of the multicast group causes recalculation of MTU, even bringing the interface up changes MTU from 4042 to 1500, which makes the system configuration inconsistent. Worse, ip_output() prefers route MTU over interface MTU, so large packets are not fragmented and dropped on floor. Fix it for ipoib(4) using the same approach (or hack) as was applied for it_tun/if_tap in r339012. Thanks to bz@ for giving the hint. Submitted by: kib@ Approved by: hselasky (mentor) MFC after: 1 week Sponsored by: Mellanox Technologies |
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drivers/infiniband | ||
include |