Signed-off-by: Pradeep Vincent <pradeepv@amazon.com>

diff --git a/drivers/xen/blkback/blkback.c b/drivers/xen/blkback/blkback.c
--- a/drivers/xen/blkback/blkback.c
+++ b/drivers/xen/blkback/blkback.c
@@ -315,6 +315,7 @@ static int do_block_io_op(blkif_t *blkif)
 	pending_req_t *pending_req;
 	RING_IDX rc, rp;
 	int more_to_do = 0;
+	unsigned long     flags;
 
 	rc = blk_rings->common.req_cons;
 	rp = blk_rings->common.sring->req_prod;
@@ -383,6 +384,15 @@ static int do_block_io_op(blkif_t *blkif)
 		cond_resched();
 	}
 
+	/* If blkback might go to sleep (i.e. more_to_do == 0) then we better
+	   let blkfront know about it (by setting req_event appropriately) so that
+	   blkfront will bother to wake us up (via interrupt) when it submits a 
+	   new I/O */
+	if (!more_to_do){
+		spin_lock_irqsave(&blkif->blk_ring_lock, flags);
+		RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do);
+		spin_unlock_irqrestore(&blkif->blk_ring_lock, flags);
+	}
 	return more_to_do;
 }