Re: [PATCH v8 36/43] dyndbg: resolve "protection" of class'd pr_debug

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 93a5a481c8b8c..a5d813ad323a1 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c

+static inline bool ddebug_class_has_param(const struct ddebug_class_map *map)
+{
+	return !!(map->controlling_param);
+}
+
+/* re-framed as a policy choice */
+#define ddebug_class_wants_protection(map) (ddebug_class_has_param(map))
+
 /*
  * Search the tables for _ddebug's which match the given `query' and
  * apply the `flags' and `mask' to them.  Returns number of matching

@@ -256,7 +299,28 @@ static bool ddebug_match_desc(const struct ddebug_query *query,
 	    dp->lineno > query->last_lineno)
 		return false;
 
-	return true;
+	/*
+	 * above are all satisfied, so we can make final decisions:
+	 * 1- class FOO or implied class __DEFAULT__
+	 * 2- site.is_classed or not
+	 */
+	if (query->class_string) {
+		/* class FOO given, exact match required */
+		return (dp->class_id == selected_class);
+	}
+	/* query class __DEFAULT__ by omission. */
+	if (dp->class_id == _DPRINTK_CLASS_DFLT) {
+		/* un-classed site */
+		return true;
+	}
+	/* site is class'd */
+	site_map = ddebug_find_map_by_class_id(di, dp->class_id);
+	if (!site_map) {
+		WARN_ONCE(1, "unknown class_id %d, check %s's CLASSMAP definitions", dp->class_id, di->mod_name);
+		return false;
+	}
+	/* module(-param) decides protection */
+	return !ddebug_class_wants_protection(site_map);
 }

@@ -1298,16 +1359,25 @@ static void ddebug_sync_classbits(const struct kernel_param *kp, const char *mod
 	}
 }
 
-static void ddebug_match_apply_kparam(const struct kernel_param *kp,
-				      const struct ddebug_class_map *map,
-				      const char *mod_name)
+static struct ddebug_class_param *
+ddebug_get_classmap_kparam(const struct kernel_param *kp,
+			   const struct ddebug_class_map *map)
 {
 	struct ddebug_class_param *dcp;
 
 	if (kp->ops != &param_ops_dyndbg_classes)
-		return;
+		return NULL;
 
 	dcp = (struct ddebug_class_param *)kp->arg;
+	return (map == dcp->map)
+		? dcp : (struct ddebug_class_param *)NULL;
+}
+
+static void ddebug_match_apply_kparam(const struct kernel_param *kp,
+				      struct ddebug_class_map *map,
+				      const char *mod_name)
+{
+	struct ddebug_class_param *dcp = ddebug_get_classmap_kparam(kp, map);
 
 	if (dcp && dcp->map == map) {
 		v2pr_info(" kp:%s.%s =0x%x", mod_name, kp->name, *dcp->bits);
 		vpr_cm_info(map, " %s maps ", mod_name);
 		ddebug_sync_classbits(kp, mod_name);
 	}
 }

@@ -1339,6 +1409,26 @@ static void ddebug_apply_params(const struct ddebug_class_map *cm, const char *m
 	}
 }
 
+#if 0
+/*
+ * called from add_module, ie early. it can find controlling kparams,
+ * which can/does? enable protection of this classmap from class-less
+ * queries, on the grounds that the user created the kparam, means to
+ * use it, and expects it to reflect reality.  We should oblige him,
+ * and protect those classmaps from classless "-p" changes.
+ */
+static void ddebug_apply_class_maps(const struct _ddebug_info *di)
+{
+	struct ddebug_class_map *cm;
+	int i;
+
+	for_subvec(i, cm, di, maps)
+		ddebug_apply_params(cm, cm->mod_name);
+
+	v2pr_di_info(di, "attached %d class-maps to ", i);
+}
+#endif
+
 static void ddebug_apply_class_users(const struct _ddebug_info *di)
 {