[PATCH v1] usb: xhci: Check return value of wait for TRB_TRANSFER event

[Minda Chen]

xhci_wait_for_event() waiting TRB_TRANSFER event may return
NULL. Checking the return value to avoid crash.

Signed-off-by: Minda Chen <minda.c...@starfivetech.com>
---
 drivers/usb/host/xhci-ring.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index c8260cbdf9..5f02ff0769 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -544,6 +544,8 @@ static void abort_td(struct usb_device *udev, int ep_index)
        xhci_queue_command(ctrl, 0, udev->slot_id, ep_index, TRB_STOP_RING);
 
        event = xhci_wait_for_event(ctrl, TRB_TRANSFER);
+       if (!event)
+               return;
        field = le32_to_cpu(event->trans_event.flags);
        BUG_ON(TRB_TO_SLOT_ID(field) != udev->slot_id);
        BUG_ON(TRB_TO_EP_INDEX(field) != ep_index);
-- 
2.17.1