Re: [PATCH v2] vhci_hcd: USB port can get stuck in the disabled state

From: Shuah Khan
Date: Thu Jul 22 2021 - 00:02:17 EST


On 7/21/21 5:55 PM, Michael Broadfoot wrote:
When a remote usb device is attached to the local Virtual USB
Host Controller Root Hub port, the bound device driver may send a
port reset command. For example to initialize firmware (eg. btusb does this).
This port reset command can be sent at any time, however the VHCI hcd
root hub is only expecting reset to occur before the device receives
SET_ADDRESS. The USB port should always be enabled after a reset
(because the port is virtual and there is no possibility of hardware errors)



Signed-off-by: Michael Broadfoot <msbroadf@xxxxxxxxx>
---
drivers/usb/usbip/vhci_hcd.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/drivers/usb/usbip/vhci_hcd.c b/drivers/usb/usbip/vhci_hcd.c
index 4ba6bcdaa8e9..d3cda1b2c15a 100644
--- a/drivers/usb/usbip/vhci_hcd.c
+++ b/drivers/usb/usbip/vhci_hcd.c
@@ -455,15 +455,10 @@ static int vhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
vhci_hcd->port_status[rhport] &= ~(1 << USB_PORT_FEAT_RESET);
vhci_hcd->re_timeout = 0;
- if (vhci_hcd->vdev[rhport].ud.status ==
- VDEV_ST_NOTASSIGNED) {
- usbip_dbg_vhci_rh(
- " enable rhport %d (status %u)\n",
- rhport,
- vhci_hcd->vdev[rhport].ud.status);
- vhci_hcd->port_status[rhport] |=
- USB_PORT_STAT_ENABLE;
- }

VDEV_ST_NOTASSIGNED status indicates that the vdev is in use without
address assigned - in other words port is initializing.

This is part of the attach request handling when user requests to
attach to a remote device. attach_store() will change the status
to VDEV_ST_NOTASSIGNED and then initiate port_connect sequence.

We don't want to touch the vdev when it is in other states.
+ usbip_dbg_vhci_rh(" enable rhport %d (status %u)\n",
+ rhport,
+ vhci_hcd->vdev[rhport].ud.status);
+ vhci_hcd->port_status[rhport] |= USB_PORT_STAT_ENABLE;
if (hcd->speed < HCD_USB3) {
switch (vhci_hcd->vdev[rhport].speed) {


How did you find this problem? Does the port get into stuck state
while attaching to a remote usbip device on the host?

thanks,
-- Shuah