--- libaitio/src/bpf.c	2013/06/25 08:53:22	1.1.2.8
+++ libaitio/src/bpf.c	2013/06/25 08:55:02	1.1.2.9
@@ -226,7 +226,8 @@ nextZCbuf(void ** __restrict zcache, struct bpf_zbuf *
 			if (buf)
 				buf = ((caddr_t) *zcache) + sizeof(struct bpf_zbuf_header);
 			ackZCbuf(bzh);
-		}
+		} else
+			io_SetErr(EAGAIN, "kernel owns the buffer");
 	} else if (*zcache == zbuf->bz_bufa) {
 		bzh = (struct bpf_zbuf_header *) zbuf->bz_bufb;
 		if (chkZCbuf(bzh)) {
@@ -235,7 +236,8 @@ nextZCbuf(void ** __restrict zcache, struct bpf_zbuf *
 			if (buf)
 				buf = ((caddr_t) *zcache) + sizeof(struct bpf_zbuf_header);
 			ackZCbuf(bzh);
-		}
+		} else
+			io_SetErr(EAGAIN, "kernel owns the buffer");
 	}
 
 	return rlen;