lib: objagg: implement optimization hints assembly and use hints for object creation

Implement simple greedy algo to find more optimized root-delta tree for
a given objagg instance. This "hints" can be used by a driver to:
1) check if the hints are better (driver's choice) than the original
   objagg tree. Driver does comparison of objagg stats and hints stats.
2) use the hints to create a new objagg instance which will construct
   the root-delta tree according to the passed hints. Currently, only a
   simple greedy algorithm is implemented. Basically it finds the roots
   according to the maximal possible user count including deltas.

Signed-off-by: Jiri Pirko <[email protected]>
Signed-off-by: Ido Schimmel <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: jpirko

drivers/net/ethernet/mellanox/mlxsw/spectrum_acl_erp.c

@@ -1200,6 +1200,32 @@ mlxsw_sp_acl_erp_delta_fill(const struct mlxsw_sp_acl_erp_key *parent_key,
 	return 0;
 }
 
+static bool mlxsw_sp_acl_erp_delta_check(void *priv, const void *parent_obj,
+					 const void *obj)
+{
+	const struct mlxsw_sp_acl_erp_key *parent_key = parent_obj;
+	const struct mlxsw_sp_acl_erp_key *key = obj;
+	u16 delta_start;
+	u8 delta_mask;
+	int err;
+
+	err = mlxsw_sp_acl_erp_delta_fill(parent_key, key,
+					  &delta_start, &delta_mask);
+	return err ? false : true;
+}
+
+static int mlxsw_sp_acl_erp_hints_obj_cmp(const void *obj1, const void *obj2)
+{
+	const struct mlxsw_sp_acl_erp_key *key1 = obj1;
+	const struct mlxsw_sp_acl_erp_key *key2 = obj2;
+
+	/* For hints purposes, two objects are considered equal
+	 * in case the masks are the same. Does not matter what
+	 * the "ctcam" value is.
+	 */
+	return memcmp(key1->mask, key2->mask, sizeof(key1->mask));
+}
+
 static void *mlxsw_sp_acl_erp_delta_create(void *priv, void *parent_obj,
 					   void *obj)
 {
@@ -1254,12 +1280,17 @@ static void mlxsw_sp_acl_erp_delta_destroy(void *priv, void *delta_priv)
 	kfree(delta);
 }
 
-static void *mlxsw_sp_acl_erp_root_create(void *priv, void *obj)
+static void *mlxsw_sp_acl_erp_root_create(void *priv, void *obj,
+					  unsigned int root_id)
 {
 	struct mlxsw_sp_acl_atcam_region *aregion = priv;
 	struct mlxsw_sp_acl_erp_table *erp_table = aregion->erp_table;
 	struct mlxsw_sp_acl_erp_key *key = obj;
 
+	if (!key->ctcam &&
+	    root_id != OBJAGG_OBJ_ROOT_ID_INVALID &&
+	    root_id >= MLXSW_SP_ACL_ERP_MAX_PER_REGION)
+		return ERR_PTR(-ENOBUFS);
 	return erp_table->ops->erp_create(erp_table, key);
 }
 
@@ -1273,6 +1304,8 @@ static void mlxsw_sp_acl_erp_root_destroy(void *priv, void *root_priv)
 
 static const struct objagg_ops mlxsw_sp_acl_erp_objagg_ops = {
 	.obj_size = sizeof(struct mlxsw_sp_acl_erp_key),
+	.delta_check = mlxsw_sp_acl_erp_delta_check,
+	.hints_obj_cmp = mlxsw_sp_acl_erp_hints_obj_cmp,
 	.delta_create = mlxsw_sp_acl_erp_delta_create,
 	.delta_destroy = mlxsw_sp_acl_erp_delta_destroy,
 	.root_create = mlxsw_sp_acl_erp_root_create,
@@ -1290,7 +1323,7 @@ mlxsw_sp_acl_erp_table_create(struct mlxsw_sp_acl_atcam_region *aregion)
 		return ERR_PTR(-ENOMEM);
 
 	erp_table->objagg = objagg_create(&mlxsw_sp_acl_erp_objagg_ops,
-					  aregion);
+					  NULL, aregion);
 	if (IS_ERR(erp_table->objagg)) {
 		err = PTR_ERR(erp_table->objagg);
 		goto err_objagg_create;

include/linux/objagg.h

@@ -6,22 +6,28 @@
 
 struct objagg_ops {
 	size_t obj_size;
+	bool (*delta_check)(void *priv, const void *parent_obj,
+			    const void *obj);
+	int (*hints_obj_cmp)(const void *obj1, const void *obj2);
 	void * (*delta_create)(void *priv, void *parent_obj, void *obj);
 	void (*delta_destroy)(void *priv, void *delta_priv);
-	void * (*root_create)(void *priv, void *obj);
+	void * (*root_create)(void *priv, void *obj, unsigned int root_id);
+#define OBJAGG_OBJ_ROOT_ID_INVALID UINT_MAX
 	void (*root_destroy)(void *priv, void *root_priv);
 };
 
 struct objagg;
 struct objagg_obj;
+struct objagg_hints;
 
 const void *objagg_obj_root_priv(const struct objagg_obj *objagg_obj);
 const void *objagg_obj_delta_priv(const struct objagg_obj *objagg_obj);
 const void *objagg_obj_raw(const struct objagg_obj *objagg_obj);
 
 struct objagg_obj *objagg_obj_get(struct objagg *objagg, void *obj);
 void objagg_obj_put(struct objagg *objagg, struct objagg_obj *objagg_obj);
-struct objagg *objagg_create(const struct objagg_ops *ops, void *priv);
+struct objagg *objagg_create(const struct objagg_ops *ops,
+			     struct objagg_hints *hints, void *priv);
 void objagg_destroy(struct objagg *objagg);
 
 struct objagg_obj_stats {
@@ -43,4 +49,14 @@ struct objagg_stats {
 const struct objagg_stats *objagg_stats_get(struct objagg *objagg);
 void objagg_stats_put(const struct objagg_stats *objagg_stats);
 
+enum objagg_opt_algo_type {
+	OBJAGG_OPT_ALGO_SIMPLE_GREEDY,
+};
+
+struct objagg_hints *objagg_hints_get(struct objagg *objagg,
+				      enum objagg_opt_algo_type opt_algo_type);
+void objagg_hints_put(struct objagg_hints *objagg_hints);
+const struct objagg_stats *
+objagg_hints_stats_get(struct objagg_hints *objagg_hints);
+
 #endif