xhci: Don't check if the event ring is valid before every event TRB

Check if the event ring exists and is valid once when the event handler
is called, not before every individual event TRB.

At this point the interrupter is valid, so no need to check that.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
Link: https://lore.kernel.org/r/20240217001017.29969-9-quic_wcheng@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-ring.c

@@ -2972,12 +2972,6 @@ static int xhci_handle_event(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
 	union xhci_trb *event;
 	u32 trb_type;
 
-	/* Event ring hasn't been allocated yet. */
-	if (!ir || !ir->event_ring || !ir->event_ring->dequeue) {
-		xhci_err(xhci, "ERROR interrupter not ready\n");
-		return -ENOMEM;
-	}
-
 	event = ir->event_ring->dequeue;
 
 	if (!unhandled_event_trb(ir->event_ring))
@@ -3081,6 +3075,12 @@ static int xhci_handle_events(struct xhci_hcd *xhci, struct xhci_interrupter *ir
 
 	xhci_clear_interrupt_pending(xhci, ir);
 
+	/* Event ring hasn't been allocated yet. */
+	if (!ir->event_ring || !ir->event_ring->dequeue) {
+		xhci_err(xhci, "ERROR interrupter event ring not ready\n");
+		return -ENOMEM;
+	}
+
 	if (xhci->xhc_state & XHCI_STATE_DYING ||
 	    xhci->xhc_state & XHCI_STATE_HALTED) {
 		xhci_dbg(xhci, "xHCI dying, ignoring interrupt. Shouldn't IRQs be disabled?\n");