linux-kernel - [PATCH 5.4 020/475] xhci: fix runtime PM imbalance in USB2 resume

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Message-Id: <20220414110855.719092898@linuxfoundation.org>
Date:   Thu, 14 Apr 2022 15:06:45 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Henry Lin <henryl@...dia.com>,
        Mathias Nyman <mathias.nyman@...ux.intel.com>
Subject: [PATCH 5.4 020/475] xhci: fix runtime PM imbalance in USB2 resume

From: Henry Lin <henryl@...dia.com>

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@...r.kernel.org
Signed-off-by: Henry Lin <henryl@...dia.com>
Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Link: https://lore.kernel.org/r/20220303110903.1662404-5-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 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
@@ -1000,6 +1000,9 @@ 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)) {