nghttpx: Don't restart SETTINGS timer, and fix log message in HTTP/2 frontend

src/shrpx_http2_upstream.cc

@@ -146,6 +146,9 @@ int Http2Upstream::upgrade_upstream(HttpsUpstream *http) {
 }
 
 void Http2Upstream::start_settings_timer() {
+  if (ev_is_active(&settings_timer_)) {
+    return;
+  }
   ev_timer_start(handler_->get_loop(), &settings_timer_);
 }
 
@@ -930,7 +933,7 @@ int Http2Upstream::on_read() {
     rv = nghttp2_session_mem_recv(session_, rb->pos, rb->rleft());
     if (rv < 0) {
       if (rv != NGHTTP2_ERR_BAD_CLIENT_MAGIC) {
-        ULOG(ERROR, this) << "nghttp2_session_recv() returned error: "
+        ULOG(ERROR, this) << "nghttp2_session_mem_recv() returned error: "
                           << nghttp2_strerror(rv);
       }
       return -1;