## Description: Fix "Message truncated" issue with many VF's
## Origin/Author: Jan Gutter <[email protected]>
## Bug: https://bugs.launchpad.net/ubuntu/+source/iproute2/+bug/1720126
Index: iproute2/lib/libnetlink.c
===================================================================
--- iproute2.orig/lib/libnetlink.c 2017-10-13 14:29:12.313074855 +0200
+++ iproute2/lib/libnetlink.c 2017-10-13 14:29:12.309074887 +0200
@@ -193,7 +193,7 @@
.msg_iov = &iov,
.msg_iovlen = 1,
};
- char buf[16384];
+ char buf[65536];
int dump_intr = 0;
iov.iov_base = buf;
--
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https://bugs.launchpad.net/bugs/1720126
Title:
[ip link] Message truncated error for large number of passthrough VFs
Status in iproute2 package in Ubuntu:
Fix Released
Status in iproute2 source package in Trusty:
New
Status in iproute2 source package in Xenial:
Confirmed
Status in iproute2 source package in Zesty:
Fix Released
Status in iproute2 package in CentOS:
Unknown
Bug description:
[Impact]
When querying a Physical Function netdev with a large amount of VF's
(more than 30), the resulting return message can overflow the 16K
netlink message buffer.
This can be fixed by enabling message peeking on the socket and
resizing the buffer on receive, or by simply enlarging the receive
buffer.
Since there's an upper limit to the number of VF's per PF, it's
relatively sane to just enlarge the receive buffer. Please see the
attached patch.
[Test Case]
# Set up 60 VF's on an SR-IOV device
ip link show > /dev/null
Observe the following:
Message truncated
Message truncated
Message truncated
[Regression Potential]
1) Applications relying on the broken behaviour will need to be updated, but
it would be a really dubious use case.
2) Increasing the rx buffer size increases the memory footprint (but
realistically, this is tiny).
3) Extra processing time is now needed to parse the larger buffer, in the
case that a call to "ip link" is on the critical time path of an application,
(called multiple times in a tight loop, for example), it would affect load.
[Other Info]
Observed on Ubuntu kernel 4.4.0-93-generic on both 14.04 and 16.04
=====================================================================================================
Ubuntu16 system
stack@cluster04:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.3 LTS
Release: 16.04
Codename: xenial
stack@cluster04:~$ uname -r
4.4.0-93-generic
stack@cluster04:~$ apt-cache policy iproute2
iproute2:
Installed: 4.3.0-1ubuntu3.16.04.1
Version table:
*** 4.3.0-1ubuntu3.16.04.1 500
500 http://us.archive.ubuntu.com/ubuntu xenial-updates/main amd64
Packages
=================================================================================================
Ubuntu14 system:
root@boomslang:~# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 14.04.3 LTS
Release: 14.04
Codename: trusty
root@boomslang:~# uname -r
4.4.0-96-generic
root@boomslang:~# apt-cache policy iproute2
iproute2:
Installed: 3.12.0-2ubuntu1
Version table:
*** 3.12.0-2ubuntu1 0
500 http://za.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64
Packages
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