usb: core: stop USB enumeration if too many retries (430d57f5) · Commits · EulixOS / Software / Kernel

Documentation/ABI/testing/sysfs-bus-usb

+11 −0

Original line number	Diff line number	Diff line
		@@ -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/.../power/usb2_lpm_l1_timeout
		Date: May 2013
		Contact: Mathias Nyman <mathias.nyman@linux.intel.com>

drivers/usb/core/hub.c

+60 −0

Original line number	Diff line number	Diff line
		@@ -3081,6 +3081,48 @@ 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)
		{
		@@ -4796,6 +4838,11 @@ 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;
		@@ -5246,6 +5293,11 @@ 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;
		@@ -5614,6 +5666,10 @@ 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;

		@@ -5927,6 +5983,10 @@ 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. */

drivers/usb/core/hub.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -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;

drivers/usb/core/port.c

+27 −0

Original line number	Diff line number	Diff line
		@@ -18,6 +18,32 @@ 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)
		{
		@@ -237,6 +263,7 @@ 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,
		};