usb: synchronize port poweroff and khubd (097a155f) · Commits · 戴 / test

If a port is powered-off, or in the process of being powered-off, prevent khubd from operating on it. Otherwise, the following sequence of events leading to an unintended disconnect may occur: Events: (0) <set pm_qos_no_poweroff to '0' for port1> (1) hub 2-2:1.0: hub_resume (2) hub 2-2:1.0: port 1: status 0301 change 0000 (3) hub 2-2:1.0: state 7 ports 4 chg 0002 evt 0000 (4) hub 2-2:1.0: port 1, power off status 0000, change 0000, 12 Mb/s (5) usb 2-2.1: USB disconnect, device number 5 Description: (1) hub is resumed before sending a ClearPortFeature request (2) hub_activate() notices the port is connected and sets hub->change_bits for the port (3) hub_events() starts, but at the same time the port suspends (4) hub_connect_change() sees the disabled port and triggers disconnect Acked-by:

Alan Stern <stern@rowland.harvard.edu> Signed-off-by:

Dan Williams <dan.j.williams@intel.com> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/hub.c

+20 −1

Original line number	Diff line number	Diff line
		@@ -4784,6 +4784,10 @@ static void port_event(struct usb_hub *hub, int port1)
		USB_PORT_FEAT_C_PORT_CONFIG_ERROR);
		}

		/* skip port actions that require the port to be powered on */
		if (!pm_runtime_active(&port_dev->dev))
		return;

		if (hub_handle_remote_wakeup(hub, port1, portstatus, portchange))
		connect_change = 1;

		@@ -4910,11 +4914,26 @@ static void hub_events(void)

		/* deal with port status changes */
		for (i = 1; i <= hdev->maxchild; i++) {
		struct usb_port *port_dev = hub->ports[i - 1];

		if (!test_bit(i, hub->busy_bits)
		&& (test_bit(i, hub->event_bits)
		\|\| test_bit(i, hub->change_bits)
		\|\| test_bit(i, hub->wakeup_bits)))
		\|\| test_bit(i, hub->wakeup_bits))) {
		/*
		* The get_noresume and barrier ensure that if
		* the port was in the process of resuming, we
		* flush that work and keep the port active for
		* the duration of the port_event(). However,
		* if the port is runtime pm suspended
		* (powered-off), we leave it in that state, run
		* an abbreviated port_event(), and move on.
		*/
		pm_runtime_get_noresume(&port_dev->dev);
		pm_runtime_barrier(&port_dev->dev);
		port_event(hub, i);
		pm_runtime_put_sync(&port_dev->dev);
		}
		}

		/* deal with hub status changes */

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