[PATCH 3.16 096/245] xhci: make sure interrupts are restored to correct state

[Ben Hutchings]

3.16.83-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>

commit bd82873f23c9a6ad834348f8b83f3b6a5bca2c65 upstream.

spin_unlock_irqrestore() might be called with stale flags after
reading port status, possibly restoring interrupts to a incorrect
state.

If a usb2 port just finished resuming while the port status is read
the spin lock will be temporary released and re-acquired in a separate
function. The flags parameter is passed as value instead of a pointer,
not updating flags properly before the final spin_unlock_irqrestore()
is called.

Fixes: 8b3d45705e54 ("usb: Fix xHCI host issues on remote wakeup.")
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20191211142007.8847-7-mathias.nyman@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/usb/host/xhci-hub.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -580,7 +580,7 @@ static u32 xhci_get_port_status(struct u
 		struct xhci_bus_state *bus_state,
 		__le32 __iomem **port_array,
 		u16 wIndex, u32 raw_port_status,
-		unsigned long flags)
+		unsigned long *flags)
 	__releases(&xhci->lock)
 	__acquires(&xhci->lock)
 {
@@ -670,12 +670,12 @@ static u32 xhci_get_port_status(struct u
 			xhci_set_link_state(xhci, port_array, wIndex,
 					XDEV_U0);
 
-			spin_unlock_irqrestore(&xhci->lock, flags);
+			spin_unlock_irqrestore(&xhci->lock, *flags);
 			time_left = wait_for_completion_timeout(
 					&bus_state->rexit_done[wIndex],
 					msecs_to_jiffies(
 						XHCI_MAX_REXIT_TIMEOUT_MS));
-			spin_lock_irqsave(&xhci->lock, flags);
+			spin_lock_irqsave(&xhci->lock, *flags);
 
 			if (time_left) {
 				slot_id = xhci_find_slot_id_by_port(hcd,
@@ -834,7 +834,7 @@ int xhci_hub_control(struct usb_hcd *hcd
 			break;
 		}
 		status = xhci_get_port_status(hcd, bus_state, port_array,
-				wIndex, temp, flags);
+				wIndex, temp, &flags);
 		if (status == 0xffffffff)
 			goto error;