Can someone can remember why?

1) Following code is added in rev. 1.42.  What was the possible
   deadlocks?  I'd like to know if there is some sample scinario.

+	/*
+	 * Mark fp non-blocking, to avoid problems from possible deadlocks.
+	 */
+
+	fp->f_flag |= FNONBLOCK;
+	(*fp->f_ops->fo_ioctl)(fp, FIONBIO, (caddr_t)&one, curp);

2) In rev. 1.39, struct ktrace_header was changed to allocated on
   stack rather than malloc.  Is this just for efficiency, or is there
   any other reason?

enami.