Index: sys/kern/kern_thread.c
===================================================================
--- sys/kern/kern_thread.c
+++ sys/kern/kern_thread.c
@@ -865,7 +865,7 @@
  *
  * Such locations include userret().
  * If the "return_instead" argument is non zero, the thread must be able to
- * accept 0 (caller may continue), or 1 (caller must abort) as a result.
+ * accept 0 (caller may continue), or non-zero (caller must abort) as a result.
  *
  * The 'return_instead' argument tells the function if it may do a
  * thread_exit() or suspend, or whether the caller must abort and back
@@ -877,11 +877,11 @@
  *
  * P_SINGLE_EXIT | return_instead == 0| return_instead != 0
  *---------------+--------------------+---------------------
- *       0       | returns 0          |   returns 0 or 1
+ *       0       | returns 0          |   returns
  *               | when ST ends       |   immediately
  *---------------+--------------------+---------------------
- *       1       | thread exits       |   returns 1
- *               |                    |  immediately
+ *       1       | thread exits       |   returns
+ *               |                    |   immediately
  * 0 = thread_exit() or suspension ok,
  * other = return error instead of stopping the thread.
  *
@@ -915,14 +915,6 @@
 			if (p->p_singlethread == td)
 				return (0);	/* Exempt from stopping. */
 		}
-		if ((p->p_flag & P_SINGLE_EXIT) && return_instead)
-			return (EINTR);
-
-		/* Should we goto user boundary if we didn't come from there? */
-		if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE &&
-		    (p->p_flag & P_SINGLE_BOUNDARY) && return_instead)
-			return (ERESTART);
-
 		/*
 		 * Ignore suspend requests if they are deferred.
 		 */
@@ -935,6 +927,9 @@
 			return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0);
 		}
 
+		if (return_instead)
+			return (ERESTART);
+
 		/*
 		 * If the process is waiting for us to exit,
 		 * this thread should just suicide.