[PATCH net-next 0/2] Add selftests helper to get N unique ports

[PATCH net-next 0/2] Add selftests helper to get N unique ports

[Dimitri Daskalakis]

The rss_ctx.py tests would occasionally flake. I found that the successive
calls to rand_port would occasionally return duplicate ports, breaking the
tests invariants.

Add a new helper that guarantees generated ports are unique.

Dimitri Daskalakis (2):
  selftests: net: py: Add rand_ports helper method
  selftests: drv-net: rss: Generate unique ports for RSS context tests

 .../drivers/net/hw/lib/py/__init__.py         |  5 ++--
 .../selftests/drivers/net/hw/rss_ctx.py       | 13 +++++-----
 .../selftests/drivers/net/lib/py/__init__.py  |  4 ++--
 .../testing/selftests/net/lib/py/__init__.py  |  5 ++--
 tools/testing/selftests/net/lib/py/utils.py   | 24 ++++++++++++++++---
 5 files changed, 35 insertions(+), 16 deletions(-)

-- 
2.47.3

[PATCH net-next 1/2] selftests: net: py: Add rand_ports helper method

[Dimitri Daskalakis]

Certain tests need a unique set of ports. Successive calls to the
existing rand_port method may return a duplicate port, resulting in test
flakiness. The new helper keeps sockets open while building a list of
ephemeral ports, thus the kernel enforces their uniqueness.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Dimitri Daskalakis <dimitri.daskalakis1@gmail.com>
---
 .../drivers/net/hw/lib/py/__init__.py         |  5 ++--
 .../selftests/drivers/net/lib/py/__init__.py  |  4 ++--
 .../testing/selftests/net/lib/py/__init__.py  |  5 ++--
 tools/testing/selftests/net/lib/py/utils.py   | 24 ++++++++++++++++---
 4 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/drivers/net/hw/lib/py/__init__.py b/tools/testing/selftests/drivers/net/hw/lib/py/__init__.py
index d5d247eca6b7..1971577d47e9 100644
--- a/tools/testing/selftests/drivers/net/hw/lib/py/__init__.py
+++ b/tools/testing/selftests/drivers/net/hw/lib/py/__init__.py
@@ -22,7 +22,8 @@ try:
         NlError, RtnlFamily, DevlinkFamily, PSPFamily
     from net.lib.py import CmdExitFailure
     from net.lib.py import bkg, cmd, bpftool, bpftrace, defer, ethtool, \
-        fd_read_timeout, ip, rand_port, wait_port_listen, wait_file, tool
+        fd_read_timeout, ip, rand_port, rand_ports, wait_port_listen, \
+        wait_file, tool
     from net.lib.py import KsftSkipEx, KsftFailEx, KsftXfailEx
     from net.lib.py import ksft_disruptive, ksft_exit, ksft_pr, ksft_run, \
         ksft_setup, ksft_variants, KsftNamedVariant
@@ -36,7 +37,7 @@ try:
                "NlError", "RtnlFamily", "DevlinkFamily", "PSPFamily",
                "CmdExitFailure",
                "bkg", "cmd", "bpftool", "bpftrace", "defer", "ethtool",
-               "fd_read_timeout", "ip", "rand_port",
+               "fd_read_timeout", "ip", "rand_port", "rand_ports",
                "wait_port_listen", "wait_file", "tool",
                "KsftSkipEx", "KsftFailEx", "KsftXfailEx",
                "ksft_disruptive", "ksft_exit", "ksft_pr", "ksft_run",
diff --git a/tools/testing/selftests/drivers/net/lib/py/__init__.py b/tools/testing/selftests/drivers/net/lib/py/__init__.py
index 8b75faa9af6d..5872d114f142 100644
--- a/tools/testing/selftests/drivers/net/lib/py/__init__.py
+++ b/tools/testing/selftests/drivers/net/lib/py/__init__.py
@@ -22,7 +22,7 @@ try:
         NlError, RtnlFamily, DevlinkFamily, PSPFamily
     from net.lib.py import CmdExitFailure
     from net.lib.py import bkg, cmd, bpftool, bpftrace, defer, ethtool, \
-        fd_read_timeout, ip, rand_port, wait_port_listen, wait_file
+        fd_read_timeout, ip, rand_port, rand_ports, wait_port_listen, wait_file
     from net.lib.py import KsftSkipEx, KsftFailEx, KsftXfailEx
     from net.lib.py import ksft_disruptive, ksft_exit, ksft_pr, ksft_run, \
         ksft_setup, ksft_variants, KsftNamedVariant
@@ -34,7 +34,7 @@ try:
                "NlError", "RtnlFamily", "DevlinkFamily", "PSPFamily",
                "CmdExitFailure",
                "bkg", "cmd", "bpftool", "bpftrace", "defer", "ethtool",
-               "fd_read_timeout", "ip", "rand_port",
+               "fd_read_timeout", "ip", "rand_port", "rand_ports",
                "wait_port_listen", "wait_file",
                "KsftSkipEx", "KsftFailEx", "KsftXfailEx",
                "ksft_disruptive", "ksft_exit", "ksft_pr", "ksft_run",
diff --git a/tools/testing/selftests/net/lib/py/__init__.py b/tools/testing/selftests/net/lib/py/__init__.py
index f528b67639de..a584e7f806a4 100644
--- a/tools/testing/selftests/net/lib/py/__init__.py
+++ b/tools/testing/selftests/net/lib/py/__init__.py
@@ -13,7 +13,8 @@ from .ksft import KsftFailEx, KsftSkipEx, KsftXfailEx, ksft_pr, ksft_eq, \
 from .netns import NetNS, NetNSEnter
 from .nsim import NetdevSim, NetdevSimDev
 from .utils import CmdExitFailure, fd_read_timeout, cmd, bkg, defer, \
-    bpftool, ip, ethtool, bpftrace, rand_port, wait_port_listen, wait_file, tool
+    bpftool, ip, ethtool, bpftrace, rand_port, rand_ports, wait_port_listen, \
+    wait_file, tool
 from .ynl import NlError, YnlFamily, EthtoolFamily, NetdevFamily, RtnlFamily, RtnlAddrFamily
 from .ynl import NetshaperFamily, DevlinkFamily, PSPFamily
 
@@ -25,7 +26,7 @@ __all__ = ["KSRC",
            "ksft_run", "ksft_exit", "ksft_variants", "KsftNamedVariant",
            "NetNS", "NetNSEnter",
            "CmdExitFailure", "fd_read_timeout", "cmd", "bkg", "defer",
-           "bpftool", "ip", "ethtool", "bpftrace", "rand_port",
+           "bpftool", "ip", "ethtool", "bpftrace", "rand_port", "rand_ports",
            "wait_port_listen", "wait_file", "tool",
            "NetdevSim", "NetdevSimDev",
            "NetshaperFamily", "DevlinkFamily", "PSPFamily", "NlError",
diff --git a/tools/testing/selftests/net/lib/py/utils.py b/tools/testing/selftests/net/lib/py/utils.py
index 85884f3e827b..487350fb957c 100644
--- a/tools/testing/selftests/net/lib/py/utils.py
+++ b/tools/testing/selftests/net/lib/py/utils.py
@@ -263,9 +263,27 @@ def rand_port(stype=socket.SOCK_STREAM):
     """
     Get a random unprivileged port.
     """
-    with socket.socket(socket.AF_INET6, stype) as s:
-        s.bind(("", 0))
-        return s.getsockname()[1]
+    return rand_ports(1, stype)[0]
+
+
+def rand_ports(count, stype=socket.SOCK_STREAM):
+    """
+    Get a unique set of random unprivileged ports.
+    """
+    sockets = []
+    ports = []
+
+    try:
+        for _ in range(count):
+            s = socket.socket(socket.AF_INET6, stype)
+            sockets.append(s)
+            s.bind(("", 0))
+            ports.append(s.getsockname()[1])
+    finally:
+        for s in sockets:
+            s.close()
+
+    return ports
 
 
 def wait_port_listen(port, proto="tcp", ns=None, host=None, sleep=0.005, deadline=5):
-- 
2.47.3

[PATCH net-next 2/2] selftests: drv-net: rss: Generate unique ports for RSS context tests

[Dimitri Daskalakis]

The RSS ctx tests rely on NFC rules with unique ports to steer packets
to the correct ctx. This updates the test to use the new rand_ports()
helper to guarantee the ports are unique.

Manual testing shows that generating 32 ports with the existing method
would result in at least one duplicate 4% of the time.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Dimitri Daskalakis <dimitri.daskalakis1@gmail.com>
---
 tools/testing/selftests/drivers/net/hw/rss_ctx.py | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/drivers/net/hw/rss_ctx.py b/tools/testing/selftests/drivers/net/hw/rss_ctx.py
index ed7e405682f0..cbeb3a38fdfe 100755
--- a/tools/testing/selftests/drivers/net/hw/rss_ctx.py
+++ b/tools/testing/selftests/drivers/net/hw/rss_ctx.py
@@ -9,7 +9,7 @@ from lib.py import ksft_eq, ksft_ne, ksft_ge, ksft_in, ksft_lt, ksft_true, ksft_
 from lib.py import NetDrvEpEnv
 from lib.py import EthtoolFamily, NetdevFamily
 from lib.py import KsftSkipEx, KsftFailEx
-from lib.py import rand_port
+from lib.py import rand_port, rand_ports
 from lib.py import ethtool, ip, defer, GenerateTraffic, CmdExitFailure
 
 
@@ -452,7 +452,7 @@ def test_rss_context(cfg, ctx_cnt=1, create_with_cfg=None):
         except:
             raise KsftSkipEx("Not enough queues for the test")
 
-    ports = []
+    ports = rand_ports(ctx_cnt)
 
     # Use queues 0 and 1 for normal traffic
     ethtool(f"-X {cfg.ifname} equal 2")
@@ -486,7 +486,6 @@ def test_rss_context(cfg, ctx_cnt=1, create_with_cfg=None):
         ksft_eq(min(data['rss-indirection-table']), 2 + i * 2, "Unexpected context cfg: " + str(data))
         ksft_eq(max(data['rss-indirection-table']), 2 + i * 2 + 1, "Unexpected context cfg: " + str(data))
 
-        ports.append(rand_port())
         flow = f"flow-type tcp{cfg.addr_ipver} dst-ip {cfg.addr} dst-port {ports[i]} context {ctx_id}"
         ntuple = ethtool_create(cfg, "-N", flow)
         defer(ethtool, f"-N {cfg.ifname} delete {ntuple}")
@@ -542,7 +541,7 @@ def test_rss_context_out_of_order(cfg, ctx_cnt=4):
 
     ntuple = []
     ctx = []
-    ports = []
+    ports = rand_ports(ctx_cnt)
 
     def remove_ctx(idx):
         ntuple[idx].exec()
@@ -574,7 +573,6 @@ def test_rss_context_out_of_order(cfg, ctx_cnt=4):
         ctx_id = ethtool_create(cfg, "-X", f"context new start {2 + i * 2} equal 2")
         ctx.append(defer(ethtool, f"-X {cfg.ifname} context {ctx_id} delete"))
 
-        ports.append(rand_port())
         flow = f"flow-type tcp{cfg.addr_ipver} dst-ip {cfg.addr} dst-port {ports[i]} context {ctx_id}"
         ntuple_id = ethtool_create(cfg, "-N", flow)
         ntuple.append(defer(ethtool, f"-N {cfg.ifname} delete {ntuple_id}"))
@@ -788,9 +786,10 @@ def test_rss_default_context_rule(cfg):
     ethtool(f"-N {cfg.ifname} {flow_generic}")
     defer(ethtool, f"-N {cfg.ifname} delete 1")
 
+    ports = rand_ports(2)
     # Specific high-priority rule for a random port that should stay on context 0.
     # Assign loc 0 so it is evaluated before the generic rule.
-    port_main = rand_port()
+    port_main = ports[0]
     flow_main = f"flow-type tcp{cfg.addr_ipver} dst-ip {cfg.addr} dst-port {port_main} context 0 loc 0"
     ethtool(f"-N {cfg.ifname} {flow_main}")
     defer(ethtool, f"-N {cfg.ifname} delete 0")
@@ -803,7 +802,7 @@ def test_rss_default_context_rule(cfg):
                           'empty' : (2, 3) })
 
     # And that traffic for any other port is steered to the new context
-    port_other = rand_port()
+    port_other = ports[1]
     _send_traffic_check(cfg, port_other, f"context {ctx_id}",
                         { 'target': (2, 3),
                           'noise' : (0, 1) })
-- 
2.47.3

Re: [PATCH net-next 2/2] selftests: drv-net: rss: Generate unique ports for RSS context tests: manual merge

[Matthieu Baerts]

Hello,

On 24/02/2026 23:46, Dimitri Daskalakis wrote:
> The RSS ctx tests rely on NFC rules with unique ports to steer packets
> to the correct ctx. This updates the test to use the new rand_ports()
> helper to guarantee the ports are unique.
> 
> Manual testing shows that generating 32 ports with the existing method
> would result in at least one duplicate 4% of the time.
FYI, we got a small conflict when merging 'net' in 'net-next' in the
MPTCP tree due to this patch applied in 'net':

  ce5a0f4612db ("selftests: drv-net: rss_ctx: test RSS contexts persist after ifdown/up")

and this one from 'net-next':

  19c3a2a81d2b ("selftests: drv-net: rss: Generate unique ports for RSS context tests")

----- Generic Message -----
The best is to avoid conflicts between 'net' and 'net-next' trees but if
they cannot be avoided when preparing patches, a note about how to fix
them is much appreciated.

The conflict has been resolved on our side [1] and the resolution we
suggest is attached to this email. Please report any issues linked to
this conflict resolution as it might be used by others. If you worked on
the mentioned patches, don't hesitate to ACK this conflict resolution.
---------------------------

This conflict was in the context: modifying one line here in 'net-next',
and the ones around in 'net'

Rerere cache is available:

 https://github.com/multipath-tcp/mptcp-upstream-rr-cache/commit/8e4747e

Cheers,
Matt

1: https://github.com/multipath-tcp/mptcp_net-next/commit/098b2437f100

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.

--------------------- 8< ---------------------
diff --cc tools/testing/selftests/drivers/net/hw/rss_ctx.py
index b9b7527c2c6b,cbeb3a38fdfe..9a1fba247708
--- a/tools/testing/selftests/drivers/net/hw/rss_ctx.py
+++ b/tools/testing/selftests/drivers/net/hw/rss_ctx.py
@@@ -10,9 -9,8 +10,9 @@@ from lib.py import ksft_eq, ksft_ne, ks
  from lib.py import NetDrvEpEnv
  from lib.py import EthtoolFamily, NetdevFamily
  from lib.py import KsftSkipEx, KsftFailEx
 +from lib.py import ksft_disruptive
- from lib.py import rand_port
+ from lib.py import rand_port, rand_ports
 -from lib.py import ethtool, ip, defer, GenerateTraffic, CmdExitFailure
 +from lib.py import cmd, ethtool, ip, defer, GenerateTraffic, CmdExitFailure, wait_file
  
  
  def _rss_key_str(key):
--------------------- 8< ---------------------

Re: [PATCH net-next 0/2] Add selftests helper to get N unique ports

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Tue, 24 Feb 2026 14:46:57 -0800 you wrote:
> The rss_ctx.py tests would occasionally flake. I found that the successive
> calls to rand_port would occasionally return duplicate ports, breaking the
> tests invariants.
> 
> Add a new helper that guarantees generated ports are unique.
> 
> Dimitri Daskalakis (2):
>   selftests: net: py: Add rand_ports helper method
>   selftests: drv-net: rss: Generate unique ports for RSS context tests
> 
> [...]

Here is the summary with links:
  - [net-next,1/2] selftests: net: py: Add rand_ports helper method
    https://git.kernel.org/netdev/net-next/c/b0249c0d41b3
  - [net-next,2/2] selftests: drv-net: rss: Generate unique ports for RSS context tests
    https://git.kernel.org/netdev/net-next/c/19c3a2a81d2b

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html