Differential D5675
dhclient: add support for interface-mtu (26) Authored by novel on Mar 18 2016, 6:19 PM. Tags None Referenced Files
Details
Make dhclient set interface MTU if it was provided. This version implements MTU setting in dhclient itself before it runs dhclient-script. Also, to be able to test this with devd, I've modified if_vtnet(4) to send LINK_(UP|DOWN) (inl. the case when MTU is being changed): https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=209427 So far it works well in my setup...
Diff Detail
Event Timeline
Comment Actions When I tested similar patch I found the problem described here https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=206721 Comment Actions Hm... I'm testing this with vtnet(4). It looks something like this: Mar 30 10:35:52 host-10-20-0-5 dhclient: New MTU (vtnet0): 1458 Mar 30 10:35:52 host-10-20-0-5 dhclient: New IP Address (vtnet0): 10.20.0.5 Mar 30 10:35:52 host-10-20-0-5 dhclient: New Subnet Mask (vtnet0): 255.255.255.0 Mar 30 10:35:52 host-10-20-0-5 dhclient: New Broadcast Address (vtnet0): 10.20.0.255 Mar 30 10:35:52 host-10-20-0-5 dhclient: New Routers (vtnet0): 10.20.0.1 Mar 30 10:35:52 host-10-20-0-5 dhclient: New Classless Static Routes (vtnet0): 169.254.169.254/32 10.20.0.1 default 10.20.0.1 I do see interface going up and down for a moment, however it does not cause dhclient restart. E.g., you can see that pids are the same: $ date Wed Mar 30 10:41:43 UTC 2016 $ ps aux|grep dhclient|grep -v grep root 45306 0.0 0.0 10588 2480 - Ss 10:35 0:00.06 dhclient: vtnet0 [priv] (dhclient) _dhcp 45328 0.0 0.0 10588 2660 - Ss 10:35 0:00.01 dhclient: vtnet0 (dhclient) $ date Wed Mar 30 10:42:59 UTC 2016 $ ps aux|grep dhclient|grep -v grep root 45306 0.0 0.0 10588 2480 - Is 10:35 0:00.07 dhclient: vtnet0 [priv] (dhclient) _dhcp 45328 0.0 0.0 10588 2660 - Is 10:35 0:00.01 dhclient: vtnet0 (dhclient) $ I don't see new records in logs either. I run it either like "dhclient -d vtnet0" or "dhclient vtnet0". Maybe some additional steps are required to reproduce that? Comment Actions I think this is specific to each network driver. if_em(4) does hardware reset on SIOCSIFMTU. As I can see, ixgbe(4) also does the same and changing MTU initiates link state change. Mar 30 15:16:46 test25 devd: Processing event '!system=IFNET subsystem=ix0 type=LINK_DOWN' Mar 30 15:16:46 test25 devd: Pushing table Mar 30 15:16:46 test25 devd: Processing notify event Mar 30 15:16:46 test25 devd: Popping table Mar 30 15:16:46 test25 devd: Processing event '!system=IFNET subsystem=ix0 type=LINK_UP' Comment Actions Hm, yes, I don't see events like that from devd, though I can see ping interrupts for a moment: 64 bytes from 10.20.0.1: icmp_seq=2 ttl=64 time=0.435 ms 64 bytes from 10.20.0.1: icmp_seq=3 ttl=64 time=0.453 ms ping: sendto: No route to host ping: sendto: No route to host 64 bytes from 10.20.0.1: icmp_seq=6 ttl=64 time=0.467 ms 64 bytes from 10.20.0.1: icmp_seq=7 ttl=64 time=0.352 ms BTW, I'm wondering if the issue you're seeing is caused by dhclient alone or because devd contains the dhclient start rule when interface goes up? Anyway, I need to find some way to reproduce it myself... On a related note, I'm wondering if vtnet(4) should spawn LINK_(UP|DOWN) events? Comment Actions Ignore the mismerge comments. I think phabricator is just confused by the lack of context. For reference, phabricator does better with full context (diff -U999999999). Comment Actions @ae could you please test the latest patch in your environment? I've tested it, but I only can test it with vtnet, and also I have to use additional patch to make it send devctl events (https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=209427). Comment Actions Now when HEAD appears to be open, this change could probably go in. However, as I don't have src commit bit, it seems that I either need to get a explicit approval or somebody else committing this. Anyway, now when bhyve got e1000 support, I can test thing change not only with my patches virtio-net, so I'll try to test it to re-confirm it addresses concerns outlined by @ae. Comment Actions e1000 support went in yesterday: https://svnweb.freebsd.org/base?view=revision&revision=302504 Comment Actions yeah, that's what I'm planning to use to test the devctl thing, because I had to patch virtio to send these events (https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=209427), but that's probably not the best testing environment... Comment Actions I can commit it for you, but I'd like wider review (i.e. someone other than me signing off on it) before I do so. Comment Actions Hi, This is something I'm just looking into again now. I have been after this since the ixv driver started working on AWS EC2 If testing by me would help get this in for 11, please let me know. Regards Jarrod Comment Actions I think the issues ae@ was referring to were resolved by having dhclient not drop the interface's configuration when the link goes down. Thus, during a link flap the interface remains configured and continues to work. (See r239564) Comment Actions I think we've missed the boat on 11.0. 12 is the current branch I would land this in. It could be MFCed for 11.1 by somebody interested. I'd still like someone else's Approval to commit, though :-). | ||||||||||||||||||||||||||||||||||||||||||||||