Skip checks on pointers and work lists when at VSL_ENDMARKER

Safe a couple of needless calls to vslc_vsm_check when we know that
there are no new records and this no need to check shm references /
the next cursor.

lib/libvarnishapi/vsl_cursor.c

@@ -125,18 +125,6 @@ vslc_vsm_next(const struct VSL_cursor *cursor)
 	assert(&c->cursor == cursor);
 	CHECK_OBJ_NOTNULL(c->vsm, VSM_MAGIC);
 
-	i = vslc_vsm_check(&c->cursor, &c->next);
-	if (i <= 0)
-		/* Overrun */
-		return (-3);
-
-	/* Check VSL fantom and abandonment */
-	if (*(volatile const uint32_t *)c->next.ptr == VSL_ENDMARKER) {
-		if (VSM_invalid == VSM_StillValid(c->vsm, &c->vf) ||
-		    VSM_Abandoned(c->vsm))
-			return (-2);
-	}
-
 	while (1) {
 		t = *(volatile const uint32_t *)c->next.ptr;
 		AN(t);
@@ -151,13 +139,18 @@ vslc_vsm_next(const struct VSL_cursor *cursor)
 		}
 
 		if (t == VSL_ENDMARKER) {
+			if (VSM_invalid == VSM_StillValid(c->vsm, &c->vf) ||
+			    VSM_Abandoned(c->vsm))
+				return (-2); /* VSL abandoned */
 			if (c->options & VSL_COPT_TAILSTOP)
-				/* EOF */
-				return (-1);
-			else
-				return (0);
+				return (-1); /* EOF */
+			return (0);	/* No new records available */
 		}
 
+		i = vslc_vsm_check(&c->cursor, &c->next);
+		if (i <= 0)
+			return (-3); /* Overrun */
+
 		c->cursor.rec = c->next;
 		c->next.ptr = VSL_NEXT(c->next.ptr);
 

lib/libvarnishapi/vsl_dispatch.c

@@ -1320,18 +1320,18 @@ VSLQ_Dispatch(struct VSLQ *vslq, VSLQ_dispatch_f *func, void *priv)
 	if (vslq->grouping == VSL_g_raw)
 		return (vslq_raw(vslq, func, priv));
 
+	/* Process next cursor input */
+	i = vslq_next(vslq);
+	if (i <= 0)
+		/* At end of log or cursor reports error condition */
+		return (i);
+
 	/* Check shmref list and buffer if necessary */
 	r = vslq_shmref_check(vslq);
 	if (r)
 		/* Buffering of shm ref failed */
 		return (r);
 
-	/* Process next cursor input */
-	i = vslq_next(vslq);
-	if (i < 0)
-		/* Cursor reports error condition */
-		return (i);
-
 	/* Check vtx timeout */
 	now = VTIM_mono();
 	while (!VTAILQ_EMPTY(&vslq->incomplete)) {