[efi] Do not attempt EFI_USB_IO_PROTOCOL transfers during shutdown

On at least some platforms (observed with a Raspberry Pi), any attempt to perform USB transfers via EFI_USB_IO_PROTOCOL during EFI shutdown will lock up the system. This is quite probably due to the already documented failure of all EFI timers when ExitBootServices() is called: see e.g. commit 5cf5ffe "[efi] Work around temporal anomaly encountered during ExitBootServices()". Work around this problem by refusing to poll endpoints if shutdown is in progress, and by immediately failing any attempts to enqueue new transfers. Signed-off-by: Michael Brown <mcb30@ipxe.org>
ipxe · Sep 15, 2019 · 41a9a5c · 41a9a5c
1 parent 4c87213
commit 41a9a5c
Showing 1 changed file with 8 additions and 0 deletions.
diff --git a/src/drivers/usb/usbio.c b/src/drivers/usb/usbio.c
@@ -972,6 +972,10 @@ static int usbio_endpoint_enqueue ( struct usb_endpoint *ep,
 	unsigned int fill;
 	unsigned int index;
 
+	/* Fail if shutdown is in progress */
+	if ( efi_shutdown_in_progress )
+		return -ECANCELED;
+
 	/* Fail if transfer ring is full */
 	fill = ( endpoint->prod - endpoint->cons );
 	if ( fill >= USBIO_RING_COUNT )
@@ -1026,6 +1030,10 @@ static int usbio_endpoint_stream ( struct usb_endpoint *ep,
  */
 static void usbio_endpoint_poll ( struct usbio_endpoint *endpoint ) {
 
+	/* Do nothing if shutdown is in progress */
+	if ( efi_shutdown_in_progress )
+		return;
+
 	/* Poll endpoint */
 	endpoint->op->poll ( endpoint );
 }