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
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/usb/core/hub.c | 21 ++++++++++++++++++++-
1 files changed, 20 insertions(+), 1 deletions(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 9632ed15d03d..ceea83350438 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4776,6 +4776,10 @@ 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;
@@ -4902,11 +4906,26 @@ 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_and_clear_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 */
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
