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UPSTREAM: usb: core: stop USB enumeration if too many retries

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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 <raychi@google.com>
Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20221107072754.3336357-1-raychi@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bug: 282876796
Change-Id: I48eff1dbbc341ef893c8abc20953b7e9a62244da
(cherry picked from commit 430d57f53eb1cdbf9ba9bbd397317912b3cd2de5)
Signed-off-by: Ray Chi <raychi@google.com>
(cherry picked from commit 278999b347af30f37e67314d7a198478b89be2dc)
This commit is contained in:
Ray Chi 2022-11-07 15:27:54 +08:00 committed by Treehugger Robot
parent 8b1bd87917
commit acb0728638
4 changed files with 102 additions and 0 deletions
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11
Documentation/ABI/testing/sysfs-bus-usb
View File

@ -264,6 +264,17 @@ Description:
attached to the port will not be detected, initialized,
or enumerated.
What: /sys/bus/usb/devices/.../<hub_interface>/port<X>/early_stop
Date: Sep 2022
Contact: Ray Chi <raychi@google.com>
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/.../<hub_interface>/port<X>/state
Date: June 2023
Contact: Roy Luo <royluo@google.com>

60
drivers/usb/core/hub.c
View File

@ -3098,6 +3098,48 @@ static int hub_port_reset(struct usb_hub *hub, int port1,
return status;
}
/*
* 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 events.
*
* Note:
* This function didn't change anything if early_stop is not set, and it will
* 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 retries)
{
struct usb_port *port_dev = 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 = 1;
} else
port_dev->ignore_event = 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)
{
@ -4813,6 +4855,11 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
do_new_scheme = use_new_scheme(udev, retry_counter, port_dev);
for (retries = 0; retries < GET_DESCRIPTOR_TRIES; (++retries, msleep(100))) {
if (hub_port_stop_enumerate(hub, port1, retries)) {
retval = -ENODEV;
break;
}
if (do_new_scheme) {
struct usb_device_descriptor *buf;
int r = 0;
@ -5263,6 +5310,11 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
status = 0;
for (i = 0; i < PORT_INIT_TRIES; i++) {
if (hub_port_stop_enumerate(hub, port1, i)) {
status = -ENODEV;
break;
}
usb_lock_port(port_dev);
mutex_lock(hcd->address0_mutex);
retry_locked = true;
@ -5631,6 +5683,10 @@ static void port_event(struct usb_hub *hub, int port1)
if (!pm_runtime_active(&port_dev->dev))
return;
/* 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 = 1;
@ -5954,6 +6010,10 @@ static int usb_reset_and_verify_device(struct usb_device *udev)
mutex_lock(hcd->address0_mutex);
for (i = 0; i < PORT_INIT_TRIES; ++i) {
if (hub_port_stop_enumerate(parent_hub, port1, i)) {
ret = -ENODEV;
break;
}
/* ep0 maxpacket size may change; let the HCD know about it.
* Other endpoints will be handled by re-enumeration. */

4
drivers/usb/core/hub.h
View File

@ -92,6 +92,8 @@ 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;
@ -107,6 +109,8 @@ 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;

27
drivers/usb/core/port.c
View File

@ -17,6 +17,32 @@ static int usb_port_block_power_off;
static const struct attribute_group *port_dev_group[];
static ssize_t early_stop_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct usb_port *port_dev = 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_attribute *attr,
const char *buf, size_t count)
{
struct usb_port *port_dev = to_usb_port(dev);
bool value;
if (kstrtobool(buf, &value))
return -EINVAL;
if (value)
port_dev->early_stop = 1;
else
port_dev->early_stop = 0;
return count;
}
static DEVICE_ATTR_RW(early_stop);
static ssize_t disable_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@ -247,6 +273,7 @@ static struct attribute *port_dev_attrs[] = {
&dev_attr_quirks.attr,
&dev_attr_over_current_count.attr,
&dev_attr_disable.attr,
&dev_attr_early_stop.attr,
NULL,
};