From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0000ECAAD5 for ; Fri, 26 Aug 2022 14:55:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239753AbiHZOzs (ORCPT ); Fri, 26 Aug 2022 10:55:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43482 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235525AbiHZOzo (ORCPT ); Fri, 26 Aug 2022 10:55:44 -0400 Received: from netrider.rowland.org (netrider.rowland.org [192.131.102.5]) by lindbergh.monkeyblade.net (Postfix) with SMTP id 7488CA2232 for ; Fri, 26 Aug 2022 07:55:42 -0700 (PDT) Received: (qmail 40232 invoked by uid 1000); 26 Aug 2022 10:55:41 -0400 Date: Fri, 26 Aug 2022 10:55:41 -0400 From: Alan Stern To: Ray Chi Cc: gregkh@linuxfoundation.org, mathias.nyman@linux.intel.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, albertccwang@google.com, badhri@google.com, pumahsu@google.com Subject: Re: [PATCH] usb: core: stop USB enumeration if too many retries Message-ID: References: <20220826075839.292615-1-raychi@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220826075839.292615-1-raychi@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 26, 2022 at 03:58:39PM +0800, Ray Chi wrote: > If a broken accessory connected to a USB host, usbcore might > keep doing enumeration retries and it will take a long time to > cause system unstable. > > This patch provides a quirk to specific USB ports of the hub to > stop USB enumeration if needed. Why only to specific ports? > Signed-off-by: Ray Chi > --- > drivers/usb/core/hub.c | 33 +++++++++++++++++++++++++++++++++ > include/linux/usb.h | 3 +++ > 2 files changed, 36 insertions(+) > > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c > index 2633acde7ac1..0f4097440ffb 100644 > --- a/drivers/usb/core/hub.c > +++ b/drivers/usb/core/hub.c > @@ -3081,6 +3081,28 @@ static int hub_port_reset(struct usb_hub *hub, int port1, > return status; > } > > +/* Stop enumerate if the port met errors and quirk is set */ > +static bool hub_port_stop_enumerate(struct usb_hub *hub, int port1, int retries) > +{ > + struct usb_port *port_dev = hub->ports[port1 - 1]; > + struct usb_device *hdev = hub->hdev; > + > + if (retries < (PORT_INIT_TRIES - 1) / 2) > + return false; > + > + /* > + * Some USB hosts can't take a long time to keep doing enumeration > + * retry. After doing half of the retries, we would turn off the port > + * power to stop enumeration if the quirk is set. > + */ > + if (port_dev->quirks & USB_PORT_QUIRK_STOP_ENUM) { > + usb_hub_set_port_power(hdev, hub, port1, false); Why turn the port power off? Aren't there better ways to stop the enumeration attempts? When will the power ever get turned back on? Why not use the initial_descriptor_timeout module parameter for this purpose? That's the sort of thing it was meant for. Alan Stern