tweak socket shutdown to eliminate race

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@2694 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/switch_rtp.c

@@ -553,8 +553,11 @@ SWITCH_DECLARE(void) switch_rtp_kill_socket(switch_rtp_t *rtp_session)
 {
 	assert(rtp_session != NULL);
 	switch_mutex_lock(rtp_session->flag_mutex);
-	apr_socket_shutdown(rtp_session->sock, APR_SHUTDOWN_READWRITE);
-	switch_clear_flag(rtp_session, SWITCH_RTP_FLAG_IO);
+	if (switch_test_flag(rtp_session, SWITCH_RTP_FLAG_IO)) {
+		assert(rtp_session->sock != NULL);
+		apr_socket_shutdown(rtp_session->sock, APR_SHUTDOWN_READWRITE);
+		switch_clear_flag(rtp_session, SWITCH_RTP_FLAG_IO);
+	}
 	switch_mutex_unlock(rtp_session->flag_mutex);
 }