xhci: Remove BUG_ON in xhci_get_input_control_ctx.

Fail gracefully, instead of causing the kernel to panic, if the input
control context doesn't have the right type (XHCI_CTX_TYPE_INPUT).  Push
finding the pointer to the input control context up into functions that
can fail.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: John Youn <johnyoun@synopsys.com>

drivers/usb/host/xhci-dbg.c

@@ -553,6 +553,11 @@ void xhci_dbg_ctx(struct xhci_hcd *xhci,
 	if (ctx->type == XHCI_CTX_TYPE_INPUT) {
 		struct xhci_input_control_ctx *ctrl_ctx =
 			xhci_get_input_control_ctx(xhci, ctx);
+		if (!ctrl_ctx) {
+			xhci_warn(xhci, "Could not get input context, bad type.\n");
+			return;
+		}
+
 		xhci_dbg(xhci, "@%p (virt) @%08llx (dma) %#08x - drop flags\n",
 			 &ctrl_ctx->drop_flags, (unsigned long long)dma,
 			 ctrl_ctx->drop_flags);

drivers/usb/host/xhci-mem.c

@@ -389,7 +389,9 @@ static void xhci_free_container_ctx(struct xhci_hcd *xhci,
 struct xhci_input_control_ctx *xhci_get_input_control_ctx(struct xhci_hcd *xhci,
 					      struct xhci_container_ctx *ctx)
 {
-	BUG_ON(ctx->type != XHCI_CTX_TYPE_INPUT);
+	if (ctx->type != XHCI_CTX_TYPE_INPUT)
+		return NULL;
+
 	return (struct xhci_input_control_ctx *)ctx->bytes;
 }
 

drivers/usb/host/xhci-ring.c

@@ -1424,6 +1424,10 @@ static void handle_cmd_completion(struct xhci_hcd *xhci,
 		 */
 		ctrl_ctx = xhci_get_input_control_ctx(xhci,
 				virt_dev->in_ctx);
+		if (!ctrl_ctx) {
+			xhci_warn(xhci, "Could not get input context, bad type.\n");
+			break;
+		}
 		/* Input ctx add_flags are the endpoint index plus one */
 		ep_index = xhci_last_valid_endpoint(le32_to_cpu(ctrl_ctx->add_flags)) - 1;
 		/* A usb_set_interface() call directly after clearing a halted