xhci: Fix Link TRB DMA in command ring stopped completion event

During the aborting of a command, the software receives a command
completion event for the command ring stopped, with the TRB pointing
to the next TRB after the aborted command.

If the command we abort is located just before the Link TRB in the
command ring, then during the 'command ring stopped' completion event,
the xHC gives the Link TRB in the event's cmd DMA, which causes a
mismatch in handling command completion event.

To address this situation, move the 'command ring stopped' completion
event check slightly earlier, since the specific command it stopped
on isn't of significant concern.

Fixes: 7f84eef ("USB: xhci: No-op command queueing and irq handler.")
Cc: [email protected]
Signed-off-by: Faisal Hassan <[email protected]>
Acked-by: Mathias Nyman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Faisal Hassan

drivers/usb/host/xhci-ring.c

@@ -1718,6 +1718,14 @@ static void handle_cmd_completion(struct xhci_hcd *xhci,
 
 	trace_xhci_handle_command(xhci->cmd_ring, &cmd_trb->generic);
 
+	cmd_comp_code = GET_COMP_CODE(le32_to_cpu(event->status));
+
+	/* If CMD ring stopped we own the trbs between enqueue and dequeue */
+	if (cmd_comp_code == COMP_COMMAND_RING_STOPPED) {
+		complete_all(&xhci->cmd_ring_stop_completion);
+		return;
+	}
+
 	cmd_dequeue_dma = xhci_trb_virt_to_dma(xhci->cmd_ring->deq_seg,
 			cmd_trb);
 	/*
@@ -1734,14 +1742,6 @@ static void handle_cmd_completion(struct xhci_hcd *xhci,
 
 	cancel_delayed_work(&xhci->cmd_timer);
 
-	cmd_comp_code = GET_COMP_CODE(le32_to_cpu(event->status));
-
-	/* If CMD ring stopped we own the trbs between enqueue and dequeue */
-	if (cmd_comp_code == COMP_COMMAND_RING_STOPPED) {
-		complete_all(&xhci->cmd_ring_stop_completion);
-		return;
-	}
-
 	if (cmd->command_trb != xhci->cmd_ring->dequeue) {
 		xhci_err(xhci,
 			 "Command completion event does not match command\n");