* [PATCH net-next] netlink: specs: Add a spec for nexthops in rtnetlink
@ 2026-10-19 6:35 Demos Ra via B4 Relay
2026-10-21 2:50 ` patchwork-bot+netdevbpf
2026-10-21 21:38 ` netdev-bot+sashiko
0 siblings, 2 replies; 3+ messages in thread
From: Demos Ra via B4 Relay @ 2026-10-19 6:35 UTC (permalink / raw)
To: David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni,
Donald Hunter, David Ahern, Ido Schimmel
Cc: Simon Horman, netdev, Demos Ra
From: Demos Ra <demosthenes.ra@gmail.com>
Add a YNL spec for nexthop objects and nexthop buckets in rtnetlink.
./tools/net/ynl/pyynl/cli.py \
--spec Documentation/netlink/specs/rt-nexthop.yaml \
--dump getnexthop
Exclude newnexthopbucket-ntf from the C code generation. ynl_gen_c.py
looks up a classic notification by the request of the same message
type, and no request uses RTM_NEWNEXTHOPBUCKET. The spec keeps the
notification, so the Python tools can still subscribe to it.
Signed-off-by: Demos Ra <demosthenes.ra@gmail.com>
---
Tested with tools/net/ynl/pyynl/cli.py on a 7.0 kernel: each
operation's replies match ip nexthop, and the create and delete
notifications are received. rt-nexthop-user.o builds with no warnings.
newnexthopbucket-ntf is left out of the C generation with
--exclude-op, as ethtool does for stats-get. If you would rather
have ynl_gen_c.py handle a notification with no matching request,
I can do that instead.
---
Documentation/netlink/specs/rt-nexthop.yaml | 761 ++++++++++++++++++++++++++++
MAINTAINERS | 1 +
tools/net/ynl/Makefile.deps | 9 +
tools/net/ynl/generated/Makefile | 1 +
4 files changed, 772 insertions(+)
diff --git a/Documentation/netlink/specs/rt-nexthop.yaml b/Documentation/netlink/specs/rt-nexthop.yaml
new file mode 100644
index 000000000..06c28fa7d
--- /dev/null
+++ b/Documentation/netlink/specs/rt-nexthop.yaml
@@ -0,0 +1,761 @@
+# SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+---
+name: rt-nexthop
+protocol: netlink-raw
+uapi-header: linux/nexthop.h
+protonum: 0
+
+doc: >-
+ Nexthop object management over rtnetlink.
+
+definitions:
+ -
+ name: nhmsg
+ type: struct
+ members:
+ -
+ name: nh-family
+ type: u8
+ -
+ name: nh-scope
+ type: u8
+ -
+ name: nh-protocol
+ type: u8
+ -
+ name: resvd
+ type: pad
+ len: 1
+ -
+ name: nh-flags
+ type: u32
+ enum: rtnh-f
+ -
+ name: rtnh-f
+ type: flags
+ name-prefix: rtnh-f-
+ enum-name:
+ entries:
+ - dead
+ - pervasive
+ - onlink
+ - offload
+ - linkdown
+ - unresolved
+ - trap
+ -
+ name: nexthop-grp
+ type: struct
+ members:
+ -
+ name: id
+ type: u32
+ -
+ name: weight
+ type: u8
+ -
+ name: weight-high
+ type: u8
+ -
+ name: resvd2
+ type: pad
+ len: 2
+ -
+ name: nexthop-grp-type
+ type: enum
+ name-prefix: nexthop-grp-type-
+ enum-name:
+ entries:
+ - mpath
+ - res
+ -
+ name: encap-type
+ type: enum
+ name-prefix: lwtunnel-encap-
+ enum-name:
+ entries:
+ - none
+ - mpls
+ - ip
+ - ila
+ - ip6
+ - seg6
+ - bpf
+ - seg6-local
+ - rpl
+ - ioam6
+ - xfrm
+ -
+ name: seg6-local-actions
+ type: enum
+ name-prefix: seg6-local-action-
+ enum-name:
+ entries:
+ - unspec
+ - end
+ - end-x
+ - end-t
+ - end-dx2
+ - end-dx6
+ - end-dx4
+ - end-dt6
+ - end-dt4
+ - end-b6
+ - end-b6-encap
+ - end-bm
+ - end-s
+ - end-as
+ - end-am
+ - end-bpf
+ - end-dt46
+ -
+ name: seg6-local-flv-ops
+ type: enum
+ name-prefix: seg6-local-flv-op-
+ enum-name:
+ entries:
+ -
+ name: unspec
+ -
+ name: psp
+ -
+ name: usp
+ -
+ name: usd
+ -
+ name: next-csid
+ -
+ name: nha-op-flag
+ type: flags
+ name-prefix: nha-op-flag-
+ enum-name:
+ entries:
+ - dump-stats
+ - dump-hw-stats
+ -
+ name: nha-op-flag-resp-grp-resvd-0
+ type: const
+ value: 2147483648
+
+sub-messages:
+ -
+ name: encap-data
+ formats:
+ -
+ value: mpls
+ attribute-set: mpls-iptunnel
+ -
+ value: ip
+ attribute-set: lwtunnel-ip
+ -
+ value: ila
+ attribute-set: ila-attrs
+ -
+ value: ip6
+ attribute-set: lwtunnel-ip6
+ -
+ value: seg6
+ attribute-set: seg6-iptunnel
+ -
+ value: bpf
+ attribute-set: lwt-bpf
+ -
+ value: seg6-local
+ attribute-set: seg6-local
+ -
+ value: rpl
+ attribute-set: rpl-iptunnel
+ -
+ value: ioam6
+ attribute-set: ioam6-iptunnel
+ -
+ value: xfrm
+ attribute-set: lwt-xfrm
+
+attribute-sets:
+ -
+ name: nexthop-attrs
+ name-prefix: nha-
+ attributes:
+ -
+ name: id
+ type: u32
+ -
+ name: group
+ type: binary # array of struct: nexthop-grp
+ -
+ name: group-type
+ type: u16
+ enum: nexthop-grp-type
+ -
+ name: blackhole
+ type: flag
+ -
+ name: oif
+ type: u32
+ -
+ name: gateway
+ type: binary
+ display-hint: ipv4-or-v6
+ -
+ name: encap-type
+ type: u16
+ enum: encap-type
+ -
+ name: encap
+ type: sub-message
+ sub-message: encap-data
+ selector: encap-type
+ -
+ name: groups
+ type: flag
+ -
+ name: master
+ type: u32
+ -
+ name: fdb
+ type: flag
+ -
+ name: res-group
+ type: nest
+ nested-attributes: res-group-attrs
+ -
+ name: res-bucket
+ type: nest
+ nested-attributes: res-bucket-attrs
+ -
+ name: op-flags
+ type: u32
+ checks:
+ flags-mask: nha-op-flag
+ -
+ name: group-stats
+ type: nest
+ nested-attributes: group-stats-attrs
+ -
+ name: hw-stats-enable
+ type: u32
+ checks:
+ max: 1
+ -
+ name: hw-stats-used
+ type: u32
+ -
+ name: dst-port
+ type: u16
+ byte-order: big-endian
+ checks:
+ min: 1
+ -
+ name: mpls-iptunnel
+ name-prefix: mpls-iptunnel-
+ header: linux/mpls_iptunnel.h
+ attributes:
+ -
+ name: dst
+ type: binary
+ -
+ name: ttl
+ type: u8
+ -
+ name: lwtunnel-ip
+ name-prefix: lwtunnel-ip-
+ header: linux/lwtunnel.h
+ attributes:
+ -
+ name: id
+ type: u64
+ byte-order: big-endian
+ -
+ name: dst
+ type: u32
+ byte-order: big-endian
+ display-hint: ipv4
+ -
+ name: src
+ type: u32
+ byte-order: big-endian
+ display-hint: ipv4
+ -
+ name: ttl
+ type: u8
+ -
+ name: tos
+ type: u8
+ -
+ name: flags
+ type: u16
+ byte-order: big-endian
+ -
+ name: pad
+ type: pad
+ -
+ name: opts
+ type: nest
+ nested-attributes: lwtunnel-ip-opts
+ -
+ name: ila-attrs
+ name-prefix: ila-attr-
+ header: linux/ila.h
+ attributes:
+ -
+ name: locator
+ type: u64
+ byte-order: big-endian
+ -
+ name: identifier
+ type: u64
+ -
+ name: locator-match
+ type: u64
+ byte-order: big-endian
+ -
+ name: ifindex
+ type: s32
+ -
+ name: dir
+ type: u32
+ -
+ name: pad
+ type: pad
+ -
+ name: csum-mode
+ type: u8
+ -
+ name: ident-type
+ type: u8
+ -
+ name: hook-type
+ type: u8
+ -
+ name: lwtunnel-ip6
+ name-prefix: lwtunnel-ip6-
+ header: linux/lwtunnel.h
+ attributes:
+ -
+ name: id
+ type: u64
+ byte-order: big-endian
+ -
+ name: dst
+ type: binary
+ display-hint: ipv6
+ -
+ name: src
+ type: binary
+ display-hint: ipv6
+ -
+ name: hoplimit
+ type: u8
+ -
+ name: tc
+ type: u8
+ -
+ name: flags
+ type: u16
+ byte-order: big-endian
+ -
+ name: pad
+ type: pad
+ -
+ name: opts
+ type: nest
+ nested-attributes: lwtunnel-ip-opts
+ -
+ name: seg6-iptunnel
+ name-prefix: seg6-iptunnel-
+ header: linux/seg6_iptunnel.h
+ attributes:
+ -
+ name: srh
+ type: binary
+ -
+ name: src
+ type: binary
+ display-hint: ipv6
+ -
+ name: table
+ type: u32
+ -
+ name: lwt-bpf
+ name-prefix: lwt-bpf-
+ header: linux/lwtunnel.h
+ attributes:
+ -
+ name: in
+ type: nest
+ nested-attributes: lwt-bpf-prog
+ -
+ name: out
+ type: nest
+ nested-attributes: lwt-bpf-prog
+ -
+ name: xmit
+ type: nest
+ nested-attributes: lwt-bpf-prog
+ -
+ name: xmit-headroom
+ type: u32
+ -
+ name: seg6-local
+ name-prefix: seg6-local-
+ header: linux/seg6_local.h
+ attributes:
+ -
+ name: action
+ type: u32
+ enum: seg6-local-actions
+ -
+ name: srh
+ type: binary
+ -
+ name: table
+ type: u32
+ -
+ name: nh4
+ type: u32
+ byte-order: big-endian
+ display-hint: ipv4
+ -
+ name: nh6
+ type: binary
+ display-hint: ipv6
+ -
+ name: iif
+ type: u32
+ -
+ name: oif
+ type: u32
+ -
+ name: bpf
+ type: nest
+ nested-attributes: seg6-local-bpf
+ -
+ name: vrftable
+ type: u32
+ -
+ name: counters
+ type: nest
+ nested-attributes: seg6-local-cnt
+ -
+ name: flavors
+ type: nest
+ nested-attributes: seg6-local-flv
+ -
+ name: rpl-iptunnel
+ name-prefix: rpl-iptunnel-
+ header: linux/rpl_iptunnel.h
+ attributes:
+ -
+ name: srh
+ type: binary
+ -
+ name: ioam6-iptunnel
+ name-prefix: ioam6-iptunnel-
+ header: linux/ioam6_iptunnel.h
+ attributes:
+ -
+ name: mode
+ type: u8
+ -
+ name: dst
+ type: binary
+ display-hint: ipv6
+ -
+ name: trace
+ type: binary
+ -
+ name: freq-k
+ type: u32
+ -
+ name: freq-n
+ type: u32
+ -
+ name: src
+ type: binary
+ display-hint: ipv6
+ -
+ name: lwt-xfrm
+ name-prefix: lwt-xfrm-
+ header: linux/lwtunnel.h
+ attributes:
+ -
+ name: if-id
+ type: u32
+ -
+ name: link
+ type: u32
+ -
+ name: lwtunnel-ip-opts
+ name-prefix: lwtunnel-ip-opts-
+ attributes:
+ -
+ name: geneve
+ type: binary
+ -
+ name: vxlan
+ type: nest
+ nested-attributes: lwtunnel-ip-opt-vxlan
+ -
+ name: erspan
+ type: nest
+ nested-attributes: lwtunnel-ip-opt-erspan
+ -
+ name: lwtunnel-ip-opt-vxlan
+ name-prefix: lwtunnel-ip-opt-vxlan-
+ attributes:
+ -
+ name: gbp
+ type: u32
+ -
+ name: lwtunnel-ip-opt-erspan
+ name-prefix: lwtunnel-ip-opt-erspan-
+ attributes:
+ -
+ name: ver
+ type: u8
+ -
+ name: index
+ type: u32
+ byte-order: big-endian
+ -
+ name: dir
+ type: u8
+ -
+ name: hwid
+ type: u8
+ -
+ name: lwt-bpf-prog
+ name-prefix: lwt-bpf-prog-
+ attributes:
+ -
+ name: fd
+ type: u32
+ -
+ name: name
+ type: string
+ checks:
+ max-len: 256
+ -
+ name: seg6-local-bpf
+ name-prefix: seg6-local-bpf-
+ attr-max-name: seg6-local-bpf-prog-max
+ attributes:
+ -
+ name: prog
+ type: u32
+ -
+ name: prog-name
+ type: string
+ checks:
+ max-len: 256
+ -
+ name: seg6-local-cnt
+ name-prefix: seg6-local-cnt-
+ attributes:
+ -
+ name: pad
+ type: pad
+ -
+ name: packets
+ type: u64
+ -
+ name: bytes
+ type: u64
+ -
+ name: errors
+ type: u64
+ -
+ name: seg6-local-flv
+ name-prefix: seg6-local-flv-
+ attributes:
+ -
+ name: operation
+ type: u32
+ enum: seg6-local-flv-ops
+ enum-as-flags: true
+ -
+ name: lcblock-bits
+ type: u8
+ -
+ name: lcnode-fn-bits
+ type: u8
+ -
+ name: res-group-attrs
+ name-prefix: nha-res-group-
+ attributes:
+ -
+ name: pad
+ type: pad
+ value: 0
+ -
+ name: buckets
+ type: u16
+ -
+ name: idle-timer
+ type: u32
+ -
+ name: unbalanced-timer
+ type: u32
+ -
+ name: unbalanced-time
+ type: u64
+ -
+ name: res-bucket-attrs
+ name-prefix: nha-res-bucket-
+ attributes:
+ -
+ name: pad
+ type: pad
+ value: 0
+ -
+ name: index
+ type: u16
+ -
+ name: idle-time
+ type: u64
+ -
+ name: nh-id
+ type: u32
+ -
+ name: group-stats-attrs
+ name-prefix: nha-group-stats-
+ attributes:
+ -
+ name: entry
+ type: nest
+ nested-attributes: group-stats-entry-attrs
+ multi-attr: true
+ -
+ name: group-stats-entry-attrs
+ name-prefix: nha-group-stats-entry-
+ attributes:
+ -
+ name: id
+ type: u32
+ -
+ name: packets
+ type: uint
+ -
+ name: packets-hw
+ type: uint
+
+operations:
+ enum-model: directional
+ fixed-header: nhmsg
+ name-prefix: rtm-
+ list:
+ -
+ name: newnexthop
+ doc: Add new nexthop entry
+ attribute-set: nexthop-attrs
+ do:
+ request:
+ value: 104
+ attributes:
+ - id
+ - group
+ - group-type
+ - blackhole
+ - oif
+ - gateway
+ - encap-type
+ - encap
+ - fdb
+ - res-group
+ - hw-stats-enable
+ - dst-port
+ -
+ name: delnexthop
+ doc: Delete nexthop with given id.
+ attribute-set: nexthop-attrs
+ do:
+ request:
+ value: 105
+ attributes:
+ - id
+ -
+ name: getnexthop
+ doc: Get or dump nexthop entries
+ attribute-set: nexthop-attrs
+ do:
+ request:
+ value: 106
+ attributes:
+ - id
+ - op-flags
+ reply:
+ value: 104
+ attributes: &nexthop-all-attrs
+ - id
+ - group
+ - group-type
+ - blackhole
+ - oif
+ - gateway
+ - encap-type
+ - encap
+ - fdb
+ - res-group
+ - op-flags
+ - group-stats
+ - hw-stats-enable
+ - hw-stats-used
+ - dst-port
+ dump:
+ request:
+ value: 106
+ attributes:
+ - oif
+ - groups
+ - master
+ - fdb
+ - op-flags
+ reply:
+ value: 104
+ attributes: *nexthop-all-attrs
+ -
+ name: newnexthop-ntf
+ doc: Notification about a created nexthop.
+ value: 104
+ notify: getnexthop
+ -
+ name: delnexthop-ntf
+ doc: Notification about a deleted nexthop.
+ value: 105
+ notify: getnexthop
+ -
+ name: getnexthopbucket
+ doc: Get or dump nexthop buckets
+ attribute-set: nexthop-attrs
+ do:
+ request:
+ value: 118
+ attributes: &nexthop-bucket-all-attrs
+ - id
+ - res-bucket
+ reply:
+ value: 116
+ attributes: *nexthop-bucket-all-attrs
+ dump:
+ request:
+ value: 118
+ attributes:
+ - id
+ - oif
+ - master
+ - res-bucket
+ reply:
+ value: 116
+ attributes: *nexthop-bucket-all-attrs
+ -
+ name: newnexthopbucket-ntf
+ doc: Notification about a created nexthop bucket.
+ value: 116
+ notify: getnexthopbucket
+
+mcast-groups:
+ list:
+ -
+ name: rtnlgrp-nexthop
+ value: 32
diff --git a/MAINTAINERS b/MAINTAINERS
index 23e919448..6a5062f02 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19144,6 +19144,7 @@ L: netdev@vger.kernel.org
S: Maintained
F: Documentation/netlink/specs/rt-addr.yaml
F: Documentation/netlink/specs/rt-neigh.yaml
+F: Documentation/netlink/specs/rt-nexthop.yaml
F: Documentation/netlink/specs/rt-route.yaml
F: Documentation/netlink/specs/rt-rule.yaml
F: include/linux/inetdevice.h
diff --git a/tools/net/ynl/Makefile.deps b/tools/net/ynl/Makefile.deps
index 3eee34e0e..9389f3752 100644
--- a/tools/net/ynl/Makefile.deps
+++ b/tools/net/ynl/Makefile.deps
@@ -45,6 +45,15 @@ CFLAGS_rt-link:=$(call get_hdr_inc,__LINUX_RTNETLINK_H,rtnetlink.h) \
$(call get_hdr_inc,_LINUX_IF_LINK_H,if_link.h)
CFLAGS_rt-neigh:=$(call get_hdr_inc,__LINUX_RTNETLINK_H,rtnetlink.h) \
$(call get_hdr_inc,__LINUX_NEIGHBOUR_H,neighbour.h)
+CFLAGS_rt-nexthop:=$(call get_hdr_inc,__LINUX_RTNETLINK_H,rtnetlink.h) \
+ $(call get_hdr_inc,_LINUX_NEXTHOP_H,nexthop.h) \
+ $(call get_hdr_inc,_LINUX_ILA_H,ila.h) \
+ $(call get_hdr_inc,_LINUX_IOAM6_IPTUNNEL_H,ioam6_iptunnel.h) \
+ $(call get_hdr_inc,_LINUX_MPLS_IPTUNNEL_H,mpls_iptunnel.h) \
+ $(call get_hdr_inc,_LINUX_RPL_IPTUNNEL_H,rpl_iptunnel.h) \
+ $(call get_hdr_inc,_LINUX_SEG6_IPTUNNEL_H,seg6_iptunnel.h) \
+ $(call get_hdr_inc,_LINUX_SEG6_LOCAL_H,seg6_local.h) \
+ $(call get_hdr_inc,_LWTUNNEL_H_,lwtunnel.h)
CFLAGS_rt-route:=$(call get_hdr_inc,_LINUX_ILA_H,ila.h) \
$(call get_hdr_inc,_LINUX_IOAM6_IPTUNNEL_H,ioam6_iptunnel.h) \
$(call get_hdr_inc,_LINUX_MPLS_IPTUNNEL_H,mpls_iptunnel.h) \
diff --git a/tools/net/ynl/generated/Makefile b/tools/net/ynl/generated/Makefile
index 5a186349b..d76d4ca94 100644
--- a/tools/net/ynl/generated/Makefile
+++ b/tools/net/ynl/generated/Makefile
@@ -18,6 +18,7 @@ include ../Makefile.deps
YNL_GEN_ARG_ethtool:=--user-header linux/ethtool_netlink.h \
--exclude-op stats-get
+YNL_GEN_ARG_rt-nexthop:=--exclude-op newnexthopbucket-ntf
TOOL:=../pyynl/ynl_gen_c.py
TOOL_RST:=../pyynl/ynl_gen_rst.py
---
base-commit: 98c2ad4f5d805dbc1ea436a334ee59311806a48c
change-id: 20261019-rt-nexthop-spec-0fc03a2c9935
Best regards,
--
Demos Ra <demosthenes.ra@gmail.com>
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH net-next] netlink: specs: Add a spec for nexthops in rtnetlink
2026-10-19 6:35 [PATCH net-next] netlink: specs: Add a spec for nexthops in rtnetlink Demos Ra via B4 Relay
@ 2026-10-21 2:50 ` patchwork-bot+netdevbpf
2026-10-21 21:38 ` netdev-bot+sashiko
1 sibling, 0 replies; 3+ messages in thread
From: patchwork-bot+netdevbpf @ 2026-10-21 2:50 UTC (permalink / raw)
To: Demos Ra
Cc: davem, edumazet, kuba, pabeni, donald.hunter, dsahern, idosch,
horms, netdev
Hello:
This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:
On Mon, 19 Oct 2026 13:35:51 +0700 you wrote:
> From: Demos Ra <demosthenes.ra@gmail.com>
>
> Add a YNL spec for nexthop objects and nexthop buckets in rtnetlink.
>
> ./tools/net/ynl/pyynl/cli.py \
> --spec Documentation/netlink/specs/rt-nexthop.yaml \
> --dump getnexthop
>
> [...]
Here is the summary with links:
- [net-next] netlink: specs: Add a spec for nexthops in rtnetlink
https://git.kernel.org/netdev/net-next/c/457dc9fefe9a
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH net-next] netlink: specs: Add a spec for nexthops in rtnetlink
2026-10-19 6:35 [PATCH net-next] netlink: specs: Add a spec for nexthops in rtnetlink Demos Ra via B4 Relay
2026-10-21 2:50 ` patchwork-bot+netdevbpf
@ 2026-10-21 21:38 ` netdev-bot+sashiko
1 sibling, 0 replies; 3+ messages in thread
From: netdev-bot+sashiko @ 2026-10-21 21:38 UTC (permalink / raw)
To: demosthenes.ra
Cc: davem, edumazet, kuba, pabeni, donald.hunter, dsahern, idosch,
horms, netdev
Thank you for your contribution! Sashiko AI review found 1 potential
issue(s) to consider.
Critical: 0 · High: 0 · Medium: 1 · Low: 0
If you believe none of the issues are legitimate, please reply to each
issue of Medium severity or higher and explain why the AI is wrong.
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(one such reply per series is enough).
- [Medium] The patch adds `YNL_GEN_ARG_rt-nexthop:=--exclude-op
newnexthopbucket-ntf` to tools/net/ynl/generated/Makefile.
--
netlink: specs: Add a spec for nexthops in rtnetlink
This commit adds a YNL netlink-raw spec for rtnetlink nexthop objects and
nexthop buckets, adds it to MAINTAINERS, and wires it into the YNL C build.
Because ynl_gen_c.py cannot match newnexthopbucket-ntf to a request, that
notification is left out of the C code generation.
> diff --git a/Documentation/netlink/specs/rt-nexthop.yaml b/Documentation/netlink/specs/rt-nexthop.yaml
> new file mode 100644
> index 0000000000000..06c28fa7d2fb6
> --- /dev/null
> +++ b/Documentation/netlink/specs/rt-nexthop.yaml
> @@ -0,0 +1,761 @@
[ ... ]
> + -
> + name: newnexthopbucket-ntf
> + doc: Notification about a created nexthop bucket.
> + value: 116
> + notify: getnexthopbucket
> +
> +mcast-groups:
> + list:
> + -
> + name: rtnlgrp-nexthop
> + value: 32
[ ... ]
> diff --git a/tools/net/ynl/generated/Makefile b/tools/net/ynl/generated/Makefile
> index 5a186349b5a86..d76d4ca946290 100644
> --- a/tools/net/ynl/generated/Makefile
> +++ b/tools/net/ynl/generated/Makefile
> @@ -18,6 +18,7 @@ include ../Makefile.deps
>
> YNL_GEN_ARG_ethtool:=--user-header linux/ethtool_netlink.h \
> --exclude-op stats-get
> +YNL_GEN_ARG_rt-nexthop:=--exclude-op newnexthopbucket-ntf
[Severity: Medium]
Will C users of the generated rt-nexthop family get parse errors when an
RTM_NEWNEXTHOPBUCKET notification arrives?
The rtnlgrp-nexthop group still carries these messages. The kernel sends
them from nexthop_bucket_notify() in net/ipv4/nexthop.c:
net/ipv4/nexthop.c:nexthop_bucket_notify() {
...
err = nh_fill_res_bucket(skb, nh, bucket, bucket_index,
RTM_NEWNEXTHOPBUCKET, 0, 0, NLM_F_REPLACE,
NULL);
...
rtnl_notify(skb, nh->net, 0, RTNLGRP_NEXTHOP, NULL, GFP_KERNEL);
}
This runs whenever notify_nl is set, and that includes the periodic upkeep
work for resilient groups:
nh_res_table_upkeep_dw()
nh_res_table_upkeep(res_table, true, true)
nh_res_bucket_migrate()
nexthop_bucket_notify()
With newnexthopbucket-ntf excluded, render_user_family() only emits
ntf_info entries for RTM_NEWNEXTHOP and RTM_DELNEXTHOP. That makes
ntf_info_size 106, so a type 116 message fails in ynl_ntf_parse():
tools/net/ynl/lib/ynl.c:ynl_ntf_parse() {
...
if (cmd >= ys->family->ntf_info_size)
return YNL_PARSE_CB_ERROR;
...
}
No error message is set. __ynl_sock_read_msgs() then skips the rest of the
receive buffer, and ynl_ntf_check() returns an error.
ynl_check_alien() reaches the same code for classic families:
if (ys->family->is_classic) {
if (nlh->nlmsg_type != rsp_cmd)
return ynl_ntf_parse(ys, nlh);
So a bucket notification that arrives during a getnexthop do or dump on a
subscribed socket would fail the whole request.
Two things limit the impact. ynl_subscribe() doesn't handle classic
families, so a C program has to join RTNLGRP_NEXTHOP by hand with
NETLINK_ADD_MEMBERSHIP on ynl_socket_get_fd(). Also, rt-link.yaml has a
similar gap: it only defines newlink-ntf, but rtnlgrp-link also carries
RTM_DELLINK.
The commit message describes the exclusion only as a codegen workaround:
ynl_gen_c.py looks up a classic notification by the request of the
same message type, and no request uses RTM_NEWNEXTHOPBUCKET.
It doesn't mention this runtime effect.
Would the alternative offered below the --- line avoid the problem? That
is, teach _render_user_ntf_entry() in ynl_gen_c.py to handle a classic
notification with no matching request. The lookup that needs the
exclusion is:
crud_op = ri.family.req_by_value[op.rsp_value]
Handling this case would keep the RTM_NEWNEXTHOPBUCKET entry in the
ntf_info table.
--
Sashiko AI review · https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20261019-rt-nexthop-spec-v1-1-9c586edf86ab%40gmail.com
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