On Sat, Oct 22, 2016 at 09:46:24AM +0200, Sven Eckelmann wrote:
The maximum MTU is defined via the slave devices of an batman-adv interface. Thus it is not possible to calculate the max_mtu during the creation of the batman-adv device when no slave devices are attached. Doing so would for example break non-fragmentation setups which then (incorrectly) allow an MTU of 1500 even when underlying device cannot transport 1500 bytes + batman-adv headers.
Checking the dynamically calculated max_mtu via the minimum of the slave devices MTU during .ndo_change_mtu is also used by the bridge interface.
Cc: Jarod Wilson jarod@redhat.com Fixes: b3e3893e1253 ("net: use core MTU range checking in misc drivers") Signed-off-by: Sven Eckelmann sven@narfation.org
Original patch + my comment: https://patchwork.ozlabs.org/patch/684722/
I just got informed about this patch when it was already applied in net-next. So I can only ask for an revet of the batman-adv parts
Apologies, I tried to cc everyone I could find in MAINTAINERS, but your name wasn't one of the three listed for batman devices. You're going to need more than just this revert though, since batman-adv calls ether_setup, which will set min_mtu = 68, max_mtu = 1500, unless batadv_hardif_min_mtu() always returns something 1500 or less. Actually, looking at that, you could omit the mtu < 68 bit from batadv_interface_change_mtu() too, since that'll already get done in the core, but I have no clue what you need for max_mtu.