From 097a155f05e88dc71184ceb93ad1aab1a13d1e41 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 20 May 2014 18:09:20 -0700 Subject: [PATCH] usb: synchronize port poweroff and khubd 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) (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 Signed-off-by: Dan Williams Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/hub.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 782ce2e31c7f..988f227e796f 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -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 */