[PATCH net-next v2 3/4] selftests: drv-net: add ability to wait for at least N packets to load gen

[Jakub Kicinski <kuba@kernel.org>]

Teach the load generator how to wait for at least given number
of packets to be received. This will be useful for filtering
where we'll want to send a non-trivial number of packets and
make sure they landed in right queues.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
v2:
 - add comment that pps or pkt_cnt are mutually exclusive (David)
 - rename variables (David)
---
 .../selftests/drivers/net/lib/py/load.py      | 30 ++++++++++++++-----
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/drivers/net/lib/py/load.py b/tools/testing/selftests/drivers/net/lib/py/load.py
index abdb677bdb1c..31f82f1e32c1 100644
--- a/tools/testing/selftests/drivers/net/lib/py/load.py
+++ b/tools/testing/selftests/drivers/net/lib/py/load.py
@@ -18,15 +18,31 @@ from lib.py import ksft_pr, cmd, ip, rand_port, wait_port_listen
                                  background=True, host=env.remote)
 
         # Wait for traffic to ramp up
-        pkt = ip("-s link show dev " + env.ifname, json=True)[0]["stats64"]["rx"]["packets"]
+        if not self._wait_pkts(pps=1000):
+            self.stop(verbose=True)
+            raise Exception("iperf3 traffic did not ramp up")
+
+    def _wait_pkts(self, pkt_cnt=None, pps=None):
+        """
+        Wait until we've seen pkt_cnt or until traffic ramps up to pps.
+        Only one of pkt_cnt or pss can be specified.
+        """
+        pkt_end = ip("-s link show dev " + self.env.ifname, json=True)[0]["stats64"]["rx"]["packets"]
         for _ in range(50):
             time.sleep(0.1)
-            now = ip("-s link show dev " + env.ifname, json=True)[0]["stats64"]["rx"]["packets"]
-            if now - pkt > 1000:
-                return
-            pkt = now
-        self.stop(verbose=True)
-        raise Exception("iperf3 traffic did not ramp up")
+            pkt_start = ip("-s link show dev " + self.env.ifname, json=True)[0]["stats64"]["rx"]["packets"]
+            if pps:
+                if pkt_start - pkt_end > pps / 10:
+                    return True
+                pkt_end = pkt_start
+            elif pkt_cnt:
+                if pkt_start - pkt_end > pkt_cnt:
+                    return True
+        return False
+
+    def wait_pkts_and_stop(self, pkt_cnt):
+        failed = not self._wait_pkts(pkt_cnt=pkt_cnt)
+        self.stop(verbose=failed)
 
     def stop(self, verbose=None):
         self._iperf_client.process(terminate=True)
-- 
2.45.2