From nobody Mon Apr 6 09:41:24 2026 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 54C27C4332F for ; Mon, 7 Nov 2022 07:29:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231519AbiKGH3S (ORCPT ); Mon, 7 Nov 2022 02:29:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40498 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231514AbiKGH3B (ORCPT ); Mon, 7 Nov 2022 02:29:01 -0500 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89E1C140F6 for ; Sun, 6 Nov 2022 23:28:00 -0800 (PST) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-368e6c449f2so101090637b3.5 for ; Sun, 06 Nov 2022 23:28:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=UZIa3TPodu5p4r3EQIwk/znAe98Z3Rc479m8woaBUnA=; b=aEZzUeFpa53BR08+bOZCPAJp68yJPGO5DYXJaFjDC+eK3wbOJd/13AecPzXdUbvVrs M2AyNgf9LIupmkjImHuk4oIu9jcmStSYc7EaoOL4VuSTRsT3z3s1PFACXjmzBMrQI48v 3rIuZ0wm5Tcc8UFVMfhF6AsW+DxTh+tTTQT4i+ZJ1yHinLbw2ISFllk/ldwcJWHiO4yQ 7PLbNNtcrQWQ7m6C7z7i+MtfYtvSGZKEWpxJwh98T7CYSMpTWyiaJjwyyIRMHVUSRIwI iYazraq5PDyCRJnjyz1hrMgGZqBUoX4DgVUL/+hs3u/1/ub80dwR+p/XvGcATp/kzwd+ lSkQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=UZIa3TPodu5p4r3EQIwk/znAe98Z3Rc479m8woaBUnA=; b=tlPxLmnBDdL+O1WrxZ6f8mCH3ormCUcdfrdFu1A6DJl/wIxSwObSJzMTC0u6hpI3KV pphwrCnxr3bWfmKUrSa9Ee6XOq28A85k0jdNhx/z8G4KBbugUaTgWznLmbyn79/3rBcE OTxMzdkFcIBgTCbmNYwEikQFsRdFNC9BNfQY3yHUMYmfRw157QGXQLIEcp10OBh2RQ5c cb+ObAgNdwcZINnKa6Ui8EDwuX2bsMej/qvgOP0+Z2fCa9SBTYYcwwmlDGYrZefPDT4o Zki7l69t8i0NvZ6vUzDj+3UN31MQLlIwEt22cH1dUG4T3Ls7VWowr61mdYrkUwoRM2Nj lc6w== X-Gm-Message-State: ACrzQf2xqU/mDh/pe3LIETs1O0q8kIy6IFWktzDH9WfJ4CFCSp0HJi1V cE3cqzHDgd6YtFRVfIPT6gz8NibBqFs= X-Google-Smtp-Source: AMsMyM6NT1BnynqufCzLVkZCmh7tZAfIYYrUmNaM8lkfWYxzxvUJnMs7cyuWsW2mdYEknS42bGjdynlQ8n8= X-Received: from raychi.tao.corp.google.com ([2401:fa00:fc:202:f4f4:86d8:c505:8643]) (user=raychi job=sendgmr) by 2002:a25:d491:0:b0:6cf:e8f1:df9b with SMTP id m139-20020a25d491000000b006cfe8f1df9bmr523202ybf.355.1667806079793; Sun, 06 Nov 2022 23:27:59 -0800 (PST) Date: Mon, 7 Nov 2022 15:27:54 +0800 Mime-Version: 1.0 X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog Message-ID: <20221107072754.3336357-1-raychi@google.com> Subject: [Patch v5] usb: core: stop USB enumeration if too many retries From: Ray Chi To: stern@rowland.harvard.edu, gregkh@linuxfoundation.org, m.grzeschik@pengutronix.de Cc: albertccwang@google.com, pumahsu@google.com, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, Ray Chi Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When a broken USB accessory connects to a USB host, usbcore might keep doing enumeration retries. If the host has a watchdog mechanism, the kernel panic will happen on the host. This patch provides an attribute early_stop to limit the numbers of retries for each port of a hub. If a port was marked with early_stop attribute, unsuccessful connection attempts will fail quickly. In addition, if an early_stop port has failed to initialize, it will ignore all future connection events until early_stop attribute is clear. Signed-off-by: Ray Chi Reviewed-by: Alan Stern --- Changes since v4: - change the location of calling hub_port_stop_enumerate() - modify if statement in hub_port_stop_enumerate() - modify if statement in port_event() Changes since v3: - rename the attribute from quick_init to early_stop - rename the variable of port_dev from ignore_connect to ignore_event - modify changelog, documentation - add more comments for hub_port_stop_enumerate() Changes since v2: - replace the quirk with the attribute - Document the attribute - modify hub_port_stop_enumerate() position in port_event() - modify the changelog Changes since v1: - remove usb_hub_set_port_power() - add a variable ignore_connect into struct port_dev - modify hub_port_stop_enumerate() and set ignore_connect in this function - avoid calling hub_port_connect_change() in port_event() --- Documentation/ABI/testing/sysfs-bus-usb | 11 +++++ drivers/usb/core/hub.c | 60 +++++++++++++++++++++++++ drivers/usb/core/hub.h | 4 ++ drivers/usb/core/port.c | 27 +++++++++++ 4 files changed, 102 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/te= sting/sysfs-bus-usb index 568103d3376e..545c2dd97ed0 100644 --- a/Documentation/ABI/testing/sysfs-bus-usb +++ b/Documentation/ABI/testing/sysfs-bus-usb @@ -264,6 +264,17 @@ Description: attached to the port will not be detected, initialized, or enumerated. =20 +What: /sys/bus/usb/devices/...//port/early_stop +Date: Sep 2022 +Contact: Ray Chi +Description: + Some USB hosts have some watchdog mechanisms so that the device + may enter ramdump if it takes a long time during port initialization. + This attribute allows each port just has two attempts so that the + port initialization will be failed quickly. In addition, if a port + which is marked with early_stop has failed to initialize, it will ignore + all future connections until this attribute is clear. + What: /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout Date: May 2013 Contact: Mathias Nyman diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index bbab424b0d55..77e73fc8d673 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -3081,6 +3081,48 @@ static int hub_port_reset(struct usb_hub *hub, int p= ort1, return status; } =20 +/* + * hub_port_stop_enumerate - stop USB enumeration or ignore port events + * @hub: target hub + * @port1: port num of the port + * @retries: port retries number of hub_port_init() + * + * Return: + * true: ignore port actions/events or give up connection attempts. + * false: keep original behavior. + * + * This function will be based on retries to check whether the port which = is + * marked with early_stop attribute would stop enumeration or ignore event= s. + * + * Note: + * This function didn't change anything if early_stop is not set, and it w= ill + * prevent all connection attempts when early_stop is set and the attempts= of + * the port are more than 1. + */ +static bool hub_port_stop_enumerate(struct usb_hub *hub, int port1, int re= tries) +{ + struct usb_port *port_dev =3D hub->ports[port1 - 1]; + + if (port_dev->early_stop) { + if (port_dev->ignore_event) + return true; + + /* + * We want unsuccessful attempts to fail quickly. + * Since some devices may need one failure during + * port initialization, we allow two tries but no + * more. + */ + if (retries < 2) + return false; + + port_dev->ignore_event =3D 1; + } else + port_dev->ignore_event =3D 0; + + return port_dev->ignore_event; +} + /* Check if a port is power on */ int usb_port_is_power_on(struct usb_hub *hub, unsigned int portstatus) { @@ -4796,6 +4838,11 @@ hub_port_init(struct usb_hub *hub, struct usb_device= *udev, int port1, do_new_scheme =3D use_new_scheme(udev, retry_counter, port_dev); =20 for (retries =3D 0; retries < GET_DESCRIPTOR_TRIES; (++retries, msleep(10= 0))) { + if (hub_port_stop_enumerate(hub, port1, retries)) { + retval =3D -ENODEV; + break; + } + if (do_new_scheme) { struct usb_device_descriptor *buf; int r =3D 0; @@ -5246,6 +5293,11 @@ static void hub_port_connect(struct usb_hub *hub, in= t port1, u16 portstatus, status =3D 0; =20 for (i =3D 0; i < PORT_INIT_TRIES; i++) { + if (hub_port_stop_enumerate(hub, port1, i)) { + status =3D -ENODEV; + break; + } + usb_lock_port(port_dev); mutex_lock(hcd->address0_mutex); retry_locked =3D true; @@ -5614,6 +5666,10 @@ static void port_event(struct usb_hub *hub, int port= 1) if (!pm_runtime_active(&port_dev->dev)) return; =20 + /* skip port actions if ignore_event and early_stop are true */ + if (port_dev->ignore_event && port_dev->early_stop) + return; + if (hub_handle_remote_wakeup(hub, port1, portstatus, portchange)) connect_change =3D 1; =20 @@ -5927,6 +5983,10 @@ static int usb_reset_and_verify_device(struct usb_de= vice *udev) mutex_lock(hcd->address0_mutex); =20 for (i =3D 0; i < PORT_INIT_TRIES; ++i) { + if (hub_port_stop_enumerate(parent_hub, port1, i)) { + ret =3D -ENODEV; + break; + } =20 /* ep0 maxpacket size may change; let the HCD know about it. * Other endpoints will be handled by re-enumeration. */ diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h index b2925856b4cb..e23833562e4f 100644 --- a/drivers/usb/core/hub.h +++ b/drivers/usb/core/hub.h @@ -90,6 +90,8 @@ struct usb_hub { * @is_superspeed cache super-speed status * @usb3_lpm_u1_permit: whether USB3 U1 LPM is permitted. * @usb3_lpm_u2_permit: whether USB3 U2 LPM is permitted. + * @early_stop: whether port initialization will be stopped earlier. + * @ignore_event: whether events of the port are ignored. */ struct usb_port { struct usb_device *child; @@ -103,6 +105,8 @@ struct usb_port { u32 over_current_count; u8 portnum; u32 quirks; + unsigned int early_stop:1; + unsigned int ignore_event:1; unsigned int is_superspeed:1; unsigned int usb3_lpm_u1_permit:1; unsigned int usb3_lpm_u2_permit:1; diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c index 015204fc67a1..06a8f1f84f6f 100644 --- a/drivers/usb/core/port.c +++ b/drivers/usb/core/port.c @@ -18,6 +18,32 @@ static int usb_port_block_power_off; =20 static const struct attribute_group *port_dev_group[]; =20 +static ssize_t early_stop_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct usb_port *port_dev =3D to_usb_port(dev); + + return sysfs_emit(buf, "%s\n", port_dev->early_stop ? "yes" : "no"); +} + +static ssize_t early_stop_store(struct device *dev, struct device_attribut= e *attr, + const char *buf, size_t count) +{ + struct usb_port *port_dev =3D to_usb_port(dev); + bool value; + + if (kstrtobool(buf, &value)) + return -EINVAL; + + if (value) + port_dev->early_stop =3D 1; + else + port_dev->early_stop =3D 0; + + return count; +} +static DEVICE_ATTR_RW(early_stop); + static ssize_t disable_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -237,6 +263,7 @@ static struct attribute *port_dev_attrs[] =3D { &dev_attr_quirks.attr, &dev_attr_over_current_count.attr, &dev_attr_disable.attr, + &dev_attr_early_stop.attr, NULL, }; =20 --=20 2.38.1.431.g37b22c650d-goog