1 files changed, 86 insertions, 51 deletions

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 0948905..5b889d4 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -381,6 +381,63 @@ get_pred_parent(struct filter_pred *pred, struct filter_pred *preds,
 	return pred;
 }
 
+enum walk_return {
+	WALK_PRED_ABORT,
+	WALK_PRED_PARENT,
+	WALK_PRED_DEFAULT,
+};
+
+typedef int (*filter_pred_walkcb_t) (enum move_type move,
+				     struct filter_pred *pred,
+				     int *err, void *data);
+
+static int walk_pred_tree(struct filter_pred *preds,
+			  struct filter_pred *root,
+			  filter_pred_walkcb_t cb, void *data)
+{
+	struct filter_pred *pred = root;
+	enum move_type move = MOVE_DOWN;
+	int done = 0;
+
+	if  (!preds)
+		return -EINVAL;
+
+	do {
+		int err = 0, ret;
+
+		ret = cb(move, pred, &err, data);
+		if (ret == WALK_PRED_ABORT)
+			return err;
+		if (ret == WALK_PRED_PARENT)
+			goto get_parent;
+
+		switch (move) {
+		case MOVE_DOWN:
+			if (pred->left != FILTER_PRED_INVALID) {
+				pred = &preds[pred->left];
+				continue;
+			}
+			goto get_parent;
+		case MOVE_UP_FROM_LEFT:
+			pred = &preds[pred->right];
+			move = MOVE_DOWN;
+			continue;
+		case MOVE_UP_FROM_RIGHT:
+ get_parent:
+			if (pred == root)
+				break;
+			pred = get_pred_parent(pred, preds,
+					       pred->parent,
+					       &move);
+			continue;
+		}
+		done = 1;
+	} while (!done);
+
+	/* We are fine. */
+	return 0;
+}
+
 /*
  * A series of AND or ORs where found together. Instead of
  * climbing up and down the tree branches, an array of the
@@ -1321,6 +1378,23 @@ static int count_preds(struct filter_parse_state *ps)
 	return n_preds;
 }
 
+struct check_pred_data {
+	int count;
+	int max;
+};
+
+static int check_pred_tree_cb(enum move_type move, struct filter_pred *pred,
+			      int *err, void *data)
+{
+	struct check_pred_data *d = data;
+
+	if (WARN_ON(d->count++ > d->max)) {
+		*err = -EINVAL;
+		return WALK_PRED_ABORT;
+	}
+	return WALK_PRED_DEFAULT;
+}
+
 /*
  * The tree is walked at filtering of an event. If the tree is not correctly
  * built, it may cause an infinite loop. Check here that the tree does
@@ -1329,58 +1403,19 @@ static int count_preds(struct filter_parse_state *ps)
 static int check_pred_tree(struct event_filter *filter,
 			   struct filter_pred *root)
 {
-	struct filter_pred *preds;
-	struct filter_pred *pred;
-	enum move_type move = MOVE_DOWN;
-	int count = 0;
-	int done = 0;
-	int max;
-
-	/*
-	 * The max that we can hit a node is three times.
-	 * Once going down, once coming up from left, and
-	 * once coming up from right. This is more than enough
-	 * since leafs are only hit a single time.
-	 */
-	max = 3 * filter->n_preds;
-
-	preds = filter->preds;
-	if  (!preds)
-		return -EINVAL;
-	pred = root;
-
-	do {
-		if (WARN_ON(count++ > max))
-			return -EINVAL;
-
-		switch (move) {
-		case MOVE_DOWN:
-			if (pred->left != FILTER_PRED_INVALID) {
-				pred = &preds[pred->left];
-				continue;
-			}
-			/* A leaf at the root is just a leaf in the tree */
-			if (pred == root)
-				break;
-			pred = get_pred_parent(pred, preds,
-					       pred->parent, &move);
-			continue;
-		case MOVE_UP_FROM_LEFT:
-			pred = &preds[pred->right];
-			move = MOVE_DOWN;
-			continue;
-		case MOVE_UP_FROM_RIGHT:
-			if (pred == root)
-				break;
-			pred = get_pred_parent(pred, preds,
-					       pred->parent, &move);
-			continue;
-		}
-		done = 1;
-	} while (!done);
+	struct check_pred_data data = {
+		/*
+		 * The max that we can hit a node is three times.
+		 * Once going down, once coming up from left, and
+		 * once coming up from right. This is more than enough
+		 * since leafs are only hit a single time.
+		 */
+		.max   = 3 * filter->n_preds,
+		.count = 0,
+	};
 
-	/* We are fine. */
-	return 0;
+	return walk_pred_tree(filter->preds, root,
+			      check_pred_tree_cb, &data);
 }
 
 static int count_leafs(struct filter_pred *preds, struct filter_pred *root)