[PATCH 5.10 027/599] xhci: fix runtime PM imbalance in USB2 resume

From: Greg Kroah-Hartman
Date: Tue Apr 05 2022 - 17:24:11 EST

From: Henry Lin <henryl@xxxxxxxxxx>

commit 70c05e4cf63054cd755ca66c1819327b22cb085f upstream.

A race between system resume and device-initiated resume may result in
runtime PM imbalance on USB2 root hub. If a device-initiated resume
starts and system resume xhci_bus_resume() directs U0 before hub driver
sees the resuming device in RESUME state, device-initiated resume will
not be finished in xhci_handle_usb2_port_link_resume(). In this case,
usb_hcd_end_port_resume() call is missing.

This changes calls usb_hcd_end_port_resume() if resuming device reaches
U0 to keep runtime PM balance.

Fixes: a231ec41e6f6 ("xhci: refactor U0 link state handling in get_port_status")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Henry Lin <henryl@xxxxxxxxxx>
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220303110903.1662404-5-mathias.nyman@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
drivers/usb/host/xhci-hub.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1002,6 +1002,9 @@ static void xhci_get_usb2_port_status(st
if (link_state == XDEV_U2)
*status |= USB_PORT_STAT_L1;
if (link_state == XDEV_U0) {
+ if (bus_state->resume_done[portnum])
+ usb_hcd_end_port_resume(&port->rhub->hcd->self,
+ portnum);
bus_state->resume_done[portnum] = 0;
clear_bit(portnum, &bus_state->resuming_ports);
if (bus_state->suspended_ports & (1 << portnum)) {