linux-kernel - [PATCH] xhci: stop polling roothubs after shutdown

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Message-ID: <20220401115916.104527-1-henryl@nvidia.com>
Date:   Fri, 1 Apr 2022 19:59:15 +0800
From:   Henry Lin <henryl@...dia.com>
To:     Mathias Nyman <mathias.nyman@...el.com>
CC:     Henry Lin <henryl@...dia.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] xhci: stop polling roothubs after shutdown

While rebooting, XHCI controller and its bus device will be shut down
in order by .shutdown callback. Stopping roothubs polling in
xhci_shutdown() can prevent XHCI driver from accessing port status
after its bus device shutdown.

Take PCIe XHCI controller as example, if XHCI driver doesn't stop roothubs
polling, XHCI driver may access PCIe BAR register for port status after
parent PCIe root port driver is shutdown and cause PCIe bus error.

Signed-off-by: Henry Lin <henryl@...dia.com>
---
 drivers/usb/host/xhci.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 2d378543bc3a..e7ae6766220e 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -780,6 +780,14 @@ void xhci_shutdown(struct usb_hcd *hcd)
 	if (xhci->quirks & XHCI_SPURIOUS_REBOOT)
 		usb_disable_xhci_ports(to_pci_dev(hcd->self.sysdev));
 
+	/* Don't poll the roothubs after shutdown. */
+	xhci_dbg(xhci, "%s: stopping usb%d port polling.\n",
+			__func__, hcd->self.busnum);
+	clear_bit(HCD_FLAG_POLL_RH, &hcd->flags);
+	del_timer_sync(&hcd->rh_timer);
+	clear_bit(HCD_FLAG_POLL_RH, &xhci->shared_hcd->flags);
+	del_timer_sync(&xhci->shared_hcd->rh_timer);
+
 	spin_lock_irq(&xhci->lock);
 	xhci_halt(xhci);
 	/* Workaround for spurious wakeups at shutdown with HSW */
-- 
2.17.1