tests: Make FST config tests more robust and easier to debug

It looks like it is possible for the separate started wpa_supplicant
process to remain running after a test case like fst_sta_config_default.
This would result in failures to run any following test case that uses
the wlan5 interface. Try to kill the process more thoroughly by waiting
for the PID file to show up and write more details into the logs to make
it easier to debug issues in this area.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

tests/hwsim/test_fst_config.py

@@ -162,7 +162,7 @@ class FstLauncher:
                            'alt-hostapd/hostapd/hostapd')
         if not os.path.exists(prg):
             prg = '../../hostapd/hostapd'
-        cmd = [ prg, '-B', '-ddd',
+        cmd = [ prg, '-B', '-dddt',
                 '-P', pidfile, '-f', mylogfile, '-g', self.hapd_fst_global]
         for i in range(0, len(self.cfgs_to_run)):
             cfg = self.cfgs_to_run[i]
@@ -189,7 +189,7 @@ class FstLauncher:
                            'alt-wpa_supplicant/wpa_supplicant/wpa_supplicant')
         if not os.path.exists(prg):
             prg = '../../wpa_supplicant/wpa_supplicant'
-        cmd = [ prg, '-B', '-ddd',
+        cmd = [ prg, '-B', '-dddt',
                 '-P' + pidfile, '-f', mylogfile, '-g', self.wsup_fst_global ]
         sta_no = 0
         for i in range(0, len(self.cfgs_to_run)):
@@ -212,18 +212,26 @@ class FstLauncher:
         """Terminates hostapd/wpa_supplicant processes previously launched with
         run_hostapd/run_wpa_supplicant"""
         pidfile = self.fst_logpath + '/' + 'myhostapd.pid'
-        self.kill_pid(pidfile)
+        self.kill_pid(pidfile, self.nof_aps > 0)
         pidfile = self.fst_logpath + '/' + 'mywpa_supplicant.pid'
-        self.kill_pid(pidfile)
+        self.kill_pid(pidfile, self.nof_stas > 0)
         self.reg_ctrl.stop()
         while len(self.cfgs_to_run) != 0:
             cfg = self.cfgs_to_run[0]
             self.remove_cfg(cfg)
 
-    def kill_pid(self, pidfile):
+    def kill_pid(self, pidfile, try_again=False):
         """Kills process by PID file"""
         if not os.path.exists(pidfile):
-            return
+            if not try_again:
+                return
+            # It might take some time for the process to write the PID file,
+            # so wait a bit longer before giving up.
+            self.logger.info("kill_pid: pidfile %s does not exist - try again after a second" % pidfile)
+            time.sleep(1)
+            if not os.path.exists(pidfile):
+                self.logger.info("kill_pid: pidfile %s does not exist - could not kill the process" % pidfile)
+                return
         pid = -1
         try:
             pf = file(pidfile, 'r')