Panic dump H2 rxbuf

bin/varnishd/http2/cache_http2_panic.c

@@ -88,6 +88,15 @@ h2_sess_panic(struct vsb *vsb, const struct sess *sp)
 		VSB_printf(vsb, "t_window = %jd, r_window = %jd,\n",
 		    r2->t_window, r2->r_window);
 
+		if (!PAN_dump_struct(vsb, r2->rxbuf, H2_RXBUF_MAGIC, "rxbuf")) {
+			VSB_printf(vsb, "stvbuf = %p,\n", r2->rxbuf->stvbuf);
+			VSB_printf(vsb,
+			    "{size, tail, head} = {%u, %ju, %ju},\n",
+			    r2->rxbuf->size, r2->rxbuf->tail, r2->rxbuf->head);
+			VSB_indent(vsb, -2);
+			VSB_cat(vsb, "},\n");
+		}
+
 		VSB_indent(vsb, -2);
 		VSB_cat(vsb, "},\n");
 	}