[PATCH net-next v2 0/3] gtp: ynl spec for the GTP netlink family, a reply-command fix, and a selftest

[PATCH net-next v2 0/3] gtp: ynl spec for the GTP netlink family, a reply-command fix, and a selftest

[Anil Kaushik]

This respins the RFC "netlink: specs: add genetlink-legacy spec for GTP"
(netdev, 2026-10-01) as a patch, and adds a driver fix the spec exposed
plus a selftest that uses it.

While writing a ynl-based selftest for the existing gtp family I found
that the GET and dump replies put the genl family id in the command
field instead of a GTP_CMD_* value. libgtpnl ignores the command so it
never mattered, but ynl rejects the reply as an unknown command and
drops it. Patch 1 fixes the driver; patches 2 and 3 then describe and
test the family.

The turnaround on the respin was slower than I would have liked: most
of the time went into pinning down the reply-command bug in patch 1
once the selftest surfaced it.

Patch 1 sets a valid command (GTP_CMD_GETPDP) in the get and dump
replies.

Patch 2 adds a genetlink-legacy ynl spec for the gtp family
(NEWPDP/DELPDP/GETPDP/ECHOREQ). Description only, no uapi change.

Patch 3 adds a selftest built on the spec: it creates a gtp device, adds
a PDP context with newpdp, checks getpdp lists it and delpdp removes it.
It skips when the kernel or iproute2 lack GTP support.

The 5G PDU Session Container / QFI work that first motivated the spec is
not part of this series; I have no mainline userspace consumer for it (my
5G user plane uses an OVS datapath, not the kernel gtp driver), so per the
discussion with Harald Welte it is parked.

Anil Kaushik (3):
  gtp: set a valid genl command in PDP context get and dump replies
  netlink: specs: add genetlink-legacy spec for GTP
  selftests: net: add a test for the gtp netlink family

 Documentation/netlink/specs/gtp.yaml          | 170 ++++++++++++++++++
 MAINTAINERS                                   |   2 +
 drivers/net/gtp.c                             |   4 +-
 tools/testing/selftests/net/Makefile          |   1 +
 tools/testing/selftests/net/gtp.py            |  77 ++++++++
 .../testing/selftests/net/lib/py/__init__.py  |   5 +-
 tools/testing/selftests/net/lib/py/ynl.py     |   8 +-
 7 files changed, 262 insertions(+), 5 deletions(-)
 create mode 100644 Documentation/netlink/specs/gtp.yaml
 create mode 100644 tools/testing/selftests/net/gtp.py

-- 
2.25.1

[PATCH net-next v2 1/3] gtp: set a valid genl command in PDP context get and dump replies

[Anil Kaushik]

gtp_genl_fill_info() stamps the reply with the command its callers pass
in. gtp_genl_get_pdp() and gtp_genl_dump_pdp() pass nlmsg_type, which in
a genl message is the dynamically assigned family id rather than a
GTP_CMD_* value, so replies to a PDP context get or dump carry a
meaningless command number.

libgtpnl ignores the command and is unaffected, but parsers that check
it (for example the ynl tooling) treat the reply as an unknown command
and discard it. Pass GTP_CMD_GETPDP, as gtp_tunnel_notify() already
passes a real command on the notification path. No uapi change.

Fixes: 459aa660eb1d ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)")
Signed-off-by: Anil Kaushik <anilkaushikwireless@gmail.com>
---
 drivers/net/gtp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index 4aff23bcf..99836b773 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -2279,7 +2279,7 @@ static int gtp_genl_get_pdp(struct sk_buff *skb, struct genl_info *info)
 	}
 
 	err = gtp_genl_fill_info(skb2, NETLINK_CB(skb).portid, info->snd_seq,
-				 0, info->nlhdr->nlmsg_type, pctx);
+				 0, GTP_CMD_GETPDP, pctx);
 	if (err < 0)
 		goto err_unlock_free;
 
@@ -2326,7 +2326,7 @@ static int gtp_genl_dump_pdp(struct sk_buff *skb,
 					    NETLINK_CB(cb->skb).portid,
 					    cb->nlh->nlmsg_seq,
 					    NLM_F_MULTI,
-					    cb->nlh->nlmsg_type, pctx)) {
+					    GTP_CMD_GETPDP, pctx)) {
 					cb->args[0] = i;
 					cb->args[1] = j;
 					cb->args[2] = (unsigned long)gtp;
-- 
2.25.1

[PATCH net-next v2 2/3] netlink: specs: add genetlink-legacy spec for GTP

[Anil Kaushik]

The GTP (GPRS Tunnelling Protocol, user plane) generic netlink family
has no YAML specification under Documentation/netlink/specs/, so it
cannot be consumed by the ynl tooling used for user-space clients,
documentation and selftests.

Add a genetlink-legacy spec describing the existing family: the PDP
context management commands (NEWPDP, DELPDP, GETPDP) and the GTP-U echo
request (ECHOREQ), the GTPA_* attribute set, and the "gtp" multicast
group. The spec is derived directly from include/uapi/linux/gtp.h and
the gtp_genl_policy / gtp_genl_ops tables in drivers/net/gtp.c; command
and attribute values match the existing uapi one-to-one.

This only adds the description; there is no kernel code or uapi change.

Signed-off-by: Anil Kaushik <anilkaushikwireless@gmail.com>
---
 Documentation/netlink/specs/gtp.yaml | 170 +++++++++++++++++++++++++++
 MAINTAINERS                          |   1 +
 2 files changed, 171 insertions(+)
 create mode 100644 Documentation/netlink/specs/gtp.yaml

diff --git a/Documentation/netlink/specs/gtp.yaml b/Documentation/netlink/specs/gtp.yaml
new file mode 100644
index 000000000..7193f5e53
--- /dev/null
+++ b/Documentation/netlink/specs/gtp.yaml
@@ -0,0 +1,170 @@
+# SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+---
+name: gtp
+
+protocol: genetlink-legacy
+
+doc: |
+  GPRS Tunnelling Protocol, user plane (GTP-U).
+
+  The gtp netdevice encapsulates and decapsulates user plane packets in
+  GTP-U tunnels (GTPv0 and GTPv1-U, see 3GPP TS 29.060 and TS 29.281).
+  This family manages the PDP contexts that describe the tunnels and
+  triggers GTP-U echo requests. It is driven by user space control planes
+  such as those built on libgtpnl.
+
+kernel-policy: global
+
+attribute-sets:
+  -
+    name: gtp
+    name-prefix: gtpa-
+    attributes:
+      -
+        name: link
+        type: u32
+        doc: ifindex of the gtp netdevice the context is attached to.
+      -
+        name: version
+        type: u32
+        doc: GTP version of the context, 0 for GTPv0 or 1 for GTPv1-U.
+      -
+        name: tid
+        type: u64
+        doc: Tunnel identifier, GTPv0 only.
+      -
+        name: peer-address
+        type: u32
+        byte-order: big-endian
+        display-hint: ipv4
+        doc: |
+          IPv4 address of the remote GSN peer (GGSN or SGSN). Also known
+          as GTPA_SGSN_ADDRESS, kept for legacy user space.
+      -
+        name: ms-address
+        type: u32
+        byte-order: big-endian
+        display-hint: ipv4
+        doc: IPv4 address of the mobile subscriber served by the context.
+      -
+        name: flow
+        type: u16
+        doc: Flow label, GTPv0 only.
+      -
+        name: net-ns-fd
+        type: u32
+        doc: File descriptor of the network namespace of the gtp netdevice.
+      -
+        name: i-tei
+        type: u32
+        doc: Ingress Tunnel Endpoint Identifier, GTPv1-U only.
+      -
+        name: o-tei
+        type: u32
+        doc: Egress Tunnel Endpoint Identifier, GTPv1-U only.
+      -
+        name: pad
+        type: pad
+      -
+        name: peer-addr6
+        type: binary
+        checks:
+          exact-len: 16
+        byte-order: big-endian
+        display-hint: ipv6
+        doc: IPv6 address of the remote GSN peer (GGSN or SGSN).
+      -
+        name: ms-addr6
+        type: binary
+        checks:
+          exact-len: 16
+        byte-order: big-endian
+        display-hint: ipv6
+        doc: IPv6 address of the mobile subscriber served by the context.
+      -
+        name: family
+        type: u8
+        doc: Address family (AF_INET or AF_INET6) of the context addresses.
+
+operations:
+  list:
+    -
+      name: newpdp
+      doc: Create or update a PDP context.
+      attribute-set: gtp
+      value: 0
+      dont-validate: [strict, dump]
+      flags: [admin-perm]
+      do:
+        request: &pdp-attrs
+          attributes:
+            - link
+            - version
+            - tid
+            - peer-address
+            - peer-addr6
+            - ms-address
+            - ms-addr6
+            - flow
+            - i-tei
+            - o-tei
+            - family
+            - net-ns-fd
+    -
+      name: delpdp
+      doc: Delete a PDP context.
+      attribute-set: gtp
+      dont-validate: [strict, dump]
+      flags: [admin-perm]
+      do:
+        request: *pdp-attrs
+    -
+      name: getpdp
+      doc: Get or dump one or more PDP contexts.
+      attribute-set: gtp
+      dont-validate: [strict, dump]
+      flags: [admin-perm]
+      do:
+        request:
+          attributes:
+            - link
+            - version
+            - tid
+            - ms-address
+            - ms-addr6
+            - i-tei
+            - family
+            - net-ns-fd
+        reply: &pdp-reply
+          attributes:
+            - version
+            - tid
+            - peer-address
+            - peer-addr6
+            - ms-address
+            - ms-addr6
+            - flow
+            - i-tei
+            - o-tei
+            - family
+      dump:
+        reply: *pdp-reply
+    -
+      name: echoreq
+      doc: Send a GTP-U echo request to a peer.
+      attribute-set: gtp
+      dont-validate: [strict, dump]
+      flags: [admin-perm]
+      do:
+        request:
+          attributes:
+            - link
+            - version
+            - peer-address
+            - peer-addr6
+            - family
+
+mcast-groups:
+  list:
+    -
+      name: gtp
diff --git a/MAINTAINERS b/MAINTAINERS
index 51873349b..a6e43995e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11421,6 +11421,7 @@ M:	Harald Welte <laforge@gnumonks.org>
 L:	osmocom-net-gprs@lists.osmocom.org
 S:	Maintained
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/pablo/gtp.git
+F:	Documentation/netlink/specs/gtp.yaml
 F:	drivers/net/gtp.c
 
 GUID PARTITION TABLE (GPT)
-- 
2.25.1

[PATCH net-next v2 3/3] selftests: net: add a test for the gtp netlink family

[Anil Kaushik]

Exercise the gtp generic netlink family through its ynl spec: create a
gtp device, add a PDP context with newpdp, check getpdp lists it and
delpdp removes it. Two more cases check that two contexts are dumped and
that deleting an unknown context fails.

Add a GtpFamily ynl wrapper and register the test.

Signed-off-by: Anil Kaushik <anilkaushikwireless@gmail.com>
---
 MAINTAINERS                                   |  1 +
 tools/testing/selftests/net/Makefile          |  1 +
 tools/testing/selftests/net/gtp.py            | 77 +++++++++++++++++++
 .../testing/selftests/net/lib/py/__init__.py  |  5 +-
 tools/testing/selftests/net/lib/py/ynl.py     |  8 +-
 5 files changed, 89 insertions(+), 3 deletions(-)
 create mode 100644 tools/testing/selftests/net/gtp.py

diff --git a/MAINTAINERS b/MAINTAINERS
index a6e43995e..8ac817a78 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11423,6 +11423,7 @@ S:	Maintained
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/pablo/gtp.git
 F:	Documentation/netlink/specs/gtp.yaml
 F:	drivers/net/gtp.c
+F:	tools/testing/selftests/net/gtp.py
 
 GUID PARTITION TABLE (GPT)
 M:	Davidlohr Bueso <dave@stgolabs.net>
diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index d4ca82fec..5366de878 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -44,6 +44,7 @@ TEST_PROGS := \
 	fin_ack_lat.sh \
 	fou_mcast_encap.sh \
 	fq_band_pktlimit.sh \
+	gtp.py \
 	gre_gso.sh \
 	gre_ipv6_lladdr.sh \
 	icmp.sh \
diff --git a/tools/testing/selftests/net/gtp.py b/tools/testing/selftests/net/gtp.py
new file mode 100644
index 000000000..984c626b7
--- /dev/null
+++ b/tools/testing/selftests/net/gtp.py
@@ -0,0 +1,77 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+"""Tests for the gtp netlink family."""
+
+from lib.py import ksft_run, ksft_exit
+from lib.py import ksft_eq, ksft_in, ksft_not_in, ksft_raises
+from lib.py import KsftSkipEx
+from lib.py import NetNS, NetNSEnter
+from lib.py import GtpFamily, NlError
+from lib.py import CmdExitFailure
+from lib.py import ip, defer
+
+
+def _add_gtp_dev(ns):
+    try:
+        ip("link add gtp0 type gtp role ggsn", ns=str(ns))
+    except CmdExitFailure:
+        raise KsftSkipEx("no gtp support (CONFIG_GTP, iproute2)")
+    defer(ip, "link del gtp0", ns=str(ns))
+    ip("link set gtp0 up", ns=str(ns))
+    return ip("-d link show gtp0", ns=str(ns), json=True)[0]["ifindex"]
+
+
+def _iteis(contexts):
+    return [c.get("i-tei") for c in contexts]
+
+
+def add_del_pdp(gtp, ns) -> None:
+    link = _add_gtp_dev(ns)
+
+    gtp.newpdp({"link": link, "version": 1,
+                "i-tei": 0x100, "o-tei": 0x200,
+                "ms-address": "10.0.0.1", "peer-address": "192.0.2.1"})
+
+    pdp = [c for c in gtp.getpdp({}, dump=True) if c.get("i-tei") == 0x100]
+    ksft_eq(len(pdp), 1)
+    ksft_eq(pdp[0]["o-tei"], 0x200)
+    ksft_eq(pdp[0]["ms-address"], "10.0.0.1")
+    ksft_eq(pdp[0]["peer-address"], "192.0.2.1")
+
+    gtp.delpdp({"link": link, "version": 1,
+                "i-tei": 0x100, "ms-address": "10.0.0.1"})
+    ksft_not_in(0x100, _iteis(gtp.getpdp({}, dump=True)))
+
+
+def add_two_pdp(gtp, ns) -> None:
+    link = _add_gtp_dev(ns)
+
+    for i_tei, o_tei, ms in ((0x111, 0x211, "10.0.1.1"),
+                             (0x112, 0x212, "10.0.1.2")):
+        gtp.newpdp({"link": link, "version": 1,
+                    "i-tei": i_tei, "o-tei": o_tei,
+                    "ms-address": ms, "peer-address": "192.0.2.5"})
+
+    iteis = _iteis(gtp.getpdp({}, dump=True))
+    ksft_in(0x111, iteis)
+    ksft_in(0x112, iteis)
+
+
+def del_unknown_pdp(gtp, ns) -> None:
+    link = _add_gtp_dev(ns)
+    with ksft_raises(NlError):
+        gtp.delpdp({"link": link, "version": 1,
+                    "i-tei": 0x999, "ms-address": "10.9.9.9"})
+
+
+def main() -> None:
+    with NetNS() as ns:
+        with NetNSEnter(str(ns)):
+            gtp = GtpFamily()
+        ksft_run([add_del_pdp, add_two_pdp, del_unknown_pdp], args=(gtp, ns))
+    ksft_exit()
+
+
+if __name__ == "__main__":
+    main()
diff --git a/tools/testing/selftests/net/lib/py/__init__.py b/tools/testing/selftests/net/lib/py/__init__.py
index 71df5880b..8d34f2659 100644
--- a/tools/testing/selftests/net/lib/py/__init__.py
+++ b/tools/testing/selftests/net/lib/py/__init__.py
@@ -18,7 +18,7 @@ from .utils import CmdExitFailure, fd_read_timeout, cmd, bkg, defer, \
 from .bpf import bpf_map_set, bpf_map_dump, bpf_prog_map_ids
 from .ynl import NlError, NlctrlFamily, YnlFamily, \
     EthtoolFamily, NetdevFamily, RtnlFamily, RtnlAddrFamily, RtnlRouteFamily
-from .ynl import NetshaperFamily, DevlinkFamily, PSPFamily, Netlink
+from .ynl import NetshaperFamily, DevlinkFamily, PSPFamily, GtpFamily, Netlink
 
 __all__ = ["KSRC",
            "KsftFailEx", "KsftSkipEx", "KsftXfailEx", "ksft_pr", "ksft_eq",
@@ -32,6 +32,7 @@ __all__ = ["KSRC",
            "wait_port_listen", "ctl_file_write", "wait_file", "tool", "tc",
            "bpf_map_set", "bpf_map_dump", "bpf_prog_map_ids",
            "NetdevSim", "NetdevSimDev",
-           "NetshaperFamily", "DevlinkFamily", "PSPFamily", "NlError",
+           "NetshaperFamily", "DevlinkFamily", "PSPFamily", "GtpFamily",
+           "NlError",
            "YnlFamily", "EthtoolFamily", "NetdevFamily", "RtnlFamily",
            "NlctrlFamily", "RtnlAddrFamily", "RtnlRouteFamily", "Netlink"]
diff --git a/tools/testing/selftests/net/lib/py/ynl.py b/tools/testing/selftests/net/lib/py/ynl.py
index 08deff756..492994812 100644
--- a/tools/testing/selftests/net/lib/py/ynl.py
+++ b/tools/testing/selftests/net/lib/py/ynl.py
@@ -31,7 +31,7 @@ __all__ = [
     "NlError", "NlPolicy", "Netlink", "YnlFamily", "SPEC_PATH",
     "EthtoolFamily", "RtnlFamily", "RtnlAddrFamily", "RtnlRouteFamily",
     "NetdevFamily", "NetshaperFamily", "NlctrlFamily", "DevlinkFamily",
-    "PSPFamily",
+    "PSPFamily", "GtpFamily",
 ]
 
 #
@@ -85,3 +85,9 @@ class PSPFamily(YnlFamily):
     def __init__(self, recv_size=0):
         super().__init__((SPEC_PATH / Path('psp.yaml')).as_posix(),
                          schema='', recv_size=recv_size)
+
+
+class GtpFamily(YnlFamily):
+    def __init__(self, recv_size=0):
+        super().__init__((SPEC_PATH / Path('gtp.yaml')).as_posix(),
+                         schema='', recv_size=recv_size)
-- 
2.25.1

Re: [PATCH net-next v2 3/3] selftests: net: add a test for the gtp netlink family

[Jakub Kicinski]

On Thu,  8 Oct 2026 18:10:31 +0000 Anil Kaushik wrote:
> Exercise the gtp generic netlink family through its ynl spec: create a
> gtp device, add a PDP context with newpdp, check getpdp lists it and
> delpdp removes it. Two more cases check that two contexts are dumped and
> that deleting an unknown context fails.
> 
> Add a GtpFamily ynl wrapper and register the test.
> 
> Signed-off-by: Anil Kaushik <anilkaushikwireless@gmail.com>
> ---
>  MAINTAINERS                                   |  1 +
>  tools/testing/selftests/net/Makefile          |  1 +
>  tools/testing/selftests/net/gtp.py            | 77 +++++++++++++++++++
>  .../testing/selftests/net/lib/py/__init__.py  |  5 +-
>  tools/testing/selftests/net/lib/py/ynl.py     |  8 +-
>  5 files changed, 89 insertions(+), 3 deletions(-)
>  create mode 100644 tools/testing/selftests/net/gtp.py

You need to add GTP to the config (please not that configs are sorted)

> diff --git a/MAINTAINERS b/MAINTAINERS
> index a6e43995e..8ac817a78 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -11423,6 +11423,7 @@ S:	Maintained
>  T:	git git://git.kernel.org/pub/scm/linux/kernel/git/pablo/gtp.git
>  F:	Documentation/netlink/specs/gtp.yaml
>  F:	drivers/net/gtp.c
> +F:	tools/testing/selftests/net/gtp.py
>  
>  GUID PARTITION TABLE (GPT)
>  M:	Davidlohr Bueso <dave@stgolabs.net>
> diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
> index d4ca82fec..5366de878 100644
> --- a/tools/testing/selftests/net/Makefile
> +++ b/tools/testing/selftests/net/Makefile
> @@ -44,6 +44,7 @@ TEST_PROGS := \
>  	fin_ack_lat.sh \
>  	fou_mcast_encap.sh \
>  	fq_band_pktlimit.sh \
> +	gtp.py \
>  	gre_gso.sh \
>  	gre_ipv6_lladdr.sh \

this is not the correct alphabetical order

>  	icmp.sh \
> diff --git a/tools/testing/selftests/net/gtp.py b/tools/testing/selftests/net/gtp.py
> new file mode 100644
> index 000000000..984c626b7
> --- /dev/null
> +++ b/tools/testing/selftests/net/gtp.py
> @@ -0,0 +1,77 @@
> +#!/usr/bin/env python3
> +# SPDX-License-Identifier: GPL-2.0
> +
> +"""Tests for the gtp netlink family."""
> +
> +from lib.py import ksft_run, ksft_exit
> +from lib.py import ksft_eq, ksft_in, ksft_not_in, ksft_raises
> +from lib.py import KsftSkipEx
> +from lib.py import NetNS, NetNSEnter
> +from lib.py import GtpFamily, NlError
> +from lib.py import CmdExitFailure
> +from lib.py import ip, defer
> +
> +
> +def _add_gtp_dev(ns):
> +    try:
> +        ip("link add gtp0 type gtp role ggsn", ns=str(ns))
> +    except CmdExitFailure:
> +        raise KsftSkipEx("no gtp support (CONFIG_GTP, iproute2)")
> +    defer(ip, "link del gtp0", ns=str(ns))
> +    ip("link set gtp0 up", ns=str(ns))
> +    return ip("-d link show gtp0", ns=str(ns), json=True)[0]["ifindex"]
> +
> +
> +def _iteis(contexts):
> +    return [c.get("i-tei") for c in contexts]
> +
> +
> +def add_del_pdp(gtp, ns) -> None:

We need a sentence or three describing what the test is trying to
validate

> +    link = _add_gtp_dev(ns)
> +
> +    gtp.newpdp({"link": link, "version": 1,
> +                "i-tei": 0x100, "o-tei": 0x200,
> +                "ms-address": "10.0.0.1", "peer-address": "192.0.2.1"})
> +
> +    pdp = [c for c in gtp.getpdp({}, dump=True) if c.get("i-tei") == 0x100]
> +    ksft_eq(len(pdp), 1)
> +    ksft_eq(pdp[0]["o-tei"], 0x200)
> +    ksft_eq(pdp[0]["ms-address"], "10.0.0.1")
> +    ksft_eq(pdp[0]["peer-address"], "192.0.2.1")
> +
> +    gtp.delpdp({"link": link, "version": 1,
> +                "i-tei": 0x100, "ms-address": "10.0.0.1"})
> +    ksft_not_in(0x100, _iteis(gtp.getpdp({}, dump=True)))
> +
> +
> +def add_two_pdp(gtp, ns) -> None:
> +    link = _add_gtp_dev(ns)
> +
> +    for i_tei, o_tei, ms in ((0x111, 0x211, "10.0.1.1"),
> +                             (0x112, 0x212, "10.0.1.2")):
> +        gtp.newpdp({"link": link, "version": 1,
> +                    "i-tei": i_tei, "o-tei": o_tei,
> +                    "ms-address": ms, "peer-address": "192.0.2.5"})
> +
> +    iteis = _iteis(gtp.getpdp({}, dump=True))
> +    ksft_in(0x111, iteis)
> +    ksft_in(0x112, iteis)
> +
> +
> +def del_unknown_pdp(gtp, ns) -> None:
> +    link = _add_gtp_dev(ns)
> +    with ksft_raises(NlError):
> +        gtp.delpdp({"link": link, "version": 1,
> +                    "i-tei": 0x999, "ms-address": "10.9.9.9"})
> +
> +
> +def main() -> None:

add some docstring here too, to avoid pylint warnings
please make sure ruff check is also clean

> +    with NetNS() as ns:
> +        with NetNSEnter(str(ns)):
> +            gtp = GtpFamily()
> +        ksft_run([add_del_pdp, add_two_pdp, del_unknown_pdp], args=(gtp, ns))
> +    ksft_exit()
> +
> +
> +if __name__ == "__main__":
> +    main()
> diff --git a/tools/testing/selftests/net/lib/py/__init__.py b/tools/testing/selftests/net/lib/py/__init__.py
> index 71df5880b..8d34f2659 100644
> --- a/tools/testing/selftests/net/lib/py/__init__.py
> +++ b/tools/testing/selftests/net/lib/py/__init__.py
> @@ -18,7 +18,7 @@ from .utils import CmdExitFailure, fd_read_timeout, cmd, bkg, defer, \
>  from .bpf import bpf_map_set, bpf_map_dump, bpf_prog_map_ids
>  from .ynl import NlError, NlctrlFamily, YnlFamily, \
>      EthtoolFamily, NetdevFamily, RtnlFamily, RtnlAddrFamily, RtnlRouteFamily
> -from .ynl import NetshaperFamily, DevlinkFamily, PSPFamily, Netlink
> +from .ynl import NetshaperFamily, DevlinkFamily, PSPFamily, GtpFamily, Netlink
>  
>  __all__ = ["KSRC",
>             "KsftFailEx", "KsftSkipEx", "KsftXfailEx", "ksft_pr", "ksft_eq",
> @@ -32,6 +32,7 @@ __all__ = ["KSRC",
>             "wait_port_listen", "ctl_file_write", "wait_file", "tool", "tc",
>             "bpf_map_set", "bpf_map_dump", "bpf_prog_map_ids",
>             "NetdevSim", "NetdevSimDev",
> -           "NetshaperFamily", "DevlinkFamily", "PSPFamily", "NlError",
> +           "NetshaperFamily", "DevlinkFamily", "PSPFamily", "GtpFamily",

strange place to insert the GtpFamily, alphabetically would be before
PSP ?