tests: Make scan_hidden more robust under heavy CPU load

It is possible for the Probe Response frame wait to time out when active
scanning is used under heavy CPU load. Make this test case more robust
by trying multiple times before declaring the scan for a hidden SSID to
have failed.

Signed-off-by: Jouni Malinen <j@w1.fi>

tests/hwsim/test_scan.py

@@ -427,8 +427,16 @@ def test_scan_hidden(dev, apdev):
     if "test-scan" in dev[0].request("SCAN_RESULTS"):
         raise Exception("BSS unexpectedly found in scan")
 
-    check_scan(dev[0], "scan_id=%d,%d,%d freq=2412 use_id=1" % (id1, id2, id3))
-    if "test-scan" not in dev[0].request("SCAN_RESULTS"):
+    # Allow multiple attempts to be more robust under heavy CPU load that can
+    # result in Probe Response frames getting sent only after the station has
+    # already stopped waiting for the response on the channel.
+    found = False
+    for i in range(10):
+        check_scan(dev[0], "scan_id=%d,%d,%d freq=2412 use_id=1" % (id1, id2, id3))
+        if "test-scan" in dev[0].request("SCAN_RESULTS"):
+            found = True
+            break
+    if not found:
         raise Exception("BSS not found in scan")
 
     if "FAIL" not in dev[0].request("SCAN scan_id=1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17"):