diff options
| author | Stephen Worley <sworley@nvidia.com> | 2021-01-27 16:20:22 -0500 |
|---|---|---|
| committer | Stephen Worley <sworley@nvidia.com> | 2021-02-01 13:02:40 -0500 |
| commit | 3d30f6defb5d0c6bc4d016b8eca114c4198acbbe (patch) | |
| tree | eb5a654c1dc05cb368cba5cec5de4bccf75ee4b9 /lib/xref.c | |
| parent | 3d3ed04d39390dc01cdebfc3b6aac523d63b4c5d (diff) | |
zebra: disallow resolution to duplicate nexthops
Disallow the resolution to nexthops that are marked duplicate.
When we are resolving to an ecmp group, it's possible this
group has duplicates.
I found this when I hit a bug where we can have groups resolving
to each other and cause the resolved->next->next pointer to increase
exponentially. Sufficiently large ecmp and zebra will grind to a hault.
Like so:
```
D> 4.4.4.14/32 [150/0] via 1.1.1.1 (recursive), weight 1, 00:00:02
* via 1.1.1.1, dummy1 onlink, weight 1, 00:00:02
via 4.4.4.1 (recursive), weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 4.4.4.2 (recursive), weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 4.4.4.3 (recursive), weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 4.4.4.4 (recursive), weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 4.4.4.5 (recursive), weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 4.4.4.6 (recursive), weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 4.4.4.7 (recursive), weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 4.4.4.8 (recursive), weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 4.4.4.9 (recursive), weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 4.4.4.10 (recursive), weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 4.4.4.11 (recursive), weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 4.4.4.12 (recursive), weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 4.4.4.13 (recursive), weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 4.4.4.15 (recursive), weight 1, 00:00:02
via 1.1.1.1, dummy1 onlink, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1 onlink, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 4.4.4.16 (recursive), weight 1, 00:00:02
via 1.1.1.1, dummy1 onlink, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
via 1.1.1.1, dummy1, weight 1, 00:00:02
D> 4.4.4.15/32 [150/0] via 1.1.1.1 (recursive), weight 1, 00:00:09
* via 1.1.1.1, dummy1 onlink, weight 1, 00:00:09
via 4.4.4.1 (recursive), weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 4.4.4.2 (recursive), weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 4.4.4.3 (recursive), weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 4.4.4.4 (recursive), weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 4.4.4.5 (recursive), weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 4.4.4.6 (recursive), weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 4.4.4.7 (recursive), weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 4.4.4.8 (recursive), weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 4.4.4.9 (recursive), weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 4.4.4.10 (recursive), weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 4.4.4.11 (recursive), weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 4.4.4.12 (recursive), weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 4.4.4.13 (recursive), weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 4.4.4.14 (recursive), weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 4.4.4.16 (recursive), weight 1, 00:00:09
via 1.1.1.1, dummy1 onlink, weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
via 1.1.1.1, dummy1, weight 1, 00:00:09
D> 4.4.4.16/32 [150/0] via 1.1.1.1 (recursive), weight 1, 00:00:19
* via 1.1.1.1, dummy1 onlink, weight 1, 00:00:19
via 4.4.4.1 (recursive), weight 1, 00:00:19
via 1.1.1.1, dummy1, weight 1, 00:00:19
via 4.4.4.2 (recursive), weight 1, 00:00:19
...............
................
and on...
```
You can repro the above via:
```
kernel routes:
1.1.1.1 dev dummy1 scope link
4.4.4.0/24 via 1.1.1.1 dev dummy1
==============================
config:
nexthop-group doof
nexthop 1.1.1.1
nexthop 4.4.4.1
nexthop 4.4.4.10
nexthop 4.4.4.11
nexthop 4.4.4.12
nexthop 4.4.4.13
nexthop 4.4.4.14
nexthop 4.4.4.15
nexthop 4.4.4.16
nexthop 4.4.4.2
nexthop 4.4.4.3
nexthop 4.4.4.4
nexthop 4.4.4.5
nexthop 4.4.4.6
nexthop 4.4.4.7
nexthop 4.4.4.8
nexthop 4.4.4.9
!
===========================
Then use sharpd to install 4.4.4.16 -> 4.4.4.1 pointing to that nexthop
group in decending order.
```
With these changes it prevents the growing ecmp above by disallowing
duplicates to be in the resolution decision. These nexthops are not
installed anyways so why should we be resolving to them?
Signed-off-by: Stephen Worley <sworley@nvidia.com>
Diffstat (limited to 'lib/xref.c')
0 files changed, 0 insertions, 0 deletions