lisa._kmod: Make use of kmod VFS to configure features

A previous patch adds support for a virtual file system (VFS)
for the lisa module. This VFS allows to configure the module
features at runtime.
Make use of this VFS to configure the desired features. Features
that have parameters can be configured from a notebook with:
"""
features = {
  "lisa__perf_counter": {
    "generic_counters":
      ["cpu_cycles", "l1d_cache", "inst_retired"]
  }
}
ftrace_coll = FtraceCollector(target, ..., kmod_features=features)
"""

Original-author: Beata Michalska <[email protected]>
Signed-off-by: Pierre Gondois <[email protected]>

lisa/_assets/kmodules/lisa/configs.c

@@ -5,9 +5,6 @@
 #include "configs.h"
 #include "feature_params.h"
 
-/* List of configs. */
-HLIST_HEAD(cfg_list);
-
 void lisa_fs_remove(struct dentry *dentry);
 
 struct lisa_cfg *allocate_lisa_cfg(const char *name)
@@ -29,12 +26,11 @@ struct lisa_cfg *allocate_lisa_cfg(const char *name)
 	return NULL;
 }
 
-int init_lisa_cfg(struct lisa_cfg *cfg, struct hlist_head *cfg_list,
+void init_lisa_cfg(struct lisa_cfg *cfg, struct hlist_head *cfg_list,
 		  struct dentry *dentry)
 {
 	cfg->dentry = dentry;
 	hlist_add_head(&cfg->node, cfg_list);
-	return 0;
 }
 
 void free_lisa_cfg(struct lisa_cfg *cfg)
@@ -61,10 +57,11 @@ void drain_lisa_cfg(struct hlist_head *head)
 		free_lisa_cfg(cfg);
 }
 
-struct lisa_cfg *find_lisa_cfg(const char *name)
+struct lisa_cfg *find_lisa_cfg(struct hlist_head *cfg_list, const char *name)
 {
 	struct lisa_cfg *cfg;
-	hlist_for_each_entry(cfg, &cfg_list, node) {
+
+	hlist_for_each_entry(cfg, cfg_list, node) {
 		if (!strcmp(cfg->name, name))
 			return cfg;
 	}

lisa/_assets/kmodules/lisa/configs.h

@@ -19,14 +19,12 @@ struct lisa_cfg {
 	char *name;
 };
 
-extern struct hlist_head cfg_list;
-
 struct lisa_cfg *allocate_lisa_cfg(const char *name);
-int init_lisa_cfg(struct lisa_cfg *cfg, struct hlist_head *cfg_list,
+void init_lisa_cfg(struct lisa_cfg *cfg, struct hlist_head *cfg_list,
 		  struct dentry *dentry);
 void free_lisa_cfg(struct lisa_cfg *cfg);
 void drain_lisa_cfg(struct hlist_head *head);
-struct lisa_cfg *find_lisa_cfg(const char *name);
+struct lisa_cfg *find_lisa_cfg(struct hlist_head *cfg_list, const char *name);
 int activate_lisa_cfg(struct lisa_cfg *cfg, bool value);
 
 #endif // _CONFIGS_H

lisa/_assets/kmodules/lisa/feature_params.c

@@ -35,6 +35,7 @@ void init_feature_param_entry_value_global(struct feature_param_entry_value *val
 void free_feature_param_entry_value(struct feature_param_entry_value *val)
 {
 	list_del(&val->node);
+	val->entry->param->ops->free_value(val);
 	kfree(val);
 }
 
@@ -340,6 +341,11 @@ feature_param_set_uint(const char *buf, struct feature_param_entry *entry)
 	return val;
 }
 
+static void feature_param_free_value_uint(struct feature_param_entry_value *val)
+{
+	return;
+}
+
 static size_t
 feature_param_stringify_uint(const struct feature_param_entry_value *val,
 			     char *buffer)
@@ -388,6 +394,11 @@ feature_param_set_string(const char *buf, struct feature_param_entry *entry)
 	return val;
 }
 
+static void feature_param_free_value_string(struct feature_param_entry_value *val)
+{
+	kfree(val->data);
+}
+
 static size_t
 feature_param_stringify_string(const struct feature_param_entry_value *val,
 			       char *buf)
@@ -415,13 +426,15 @@ feature_param_copy_string(const struct feature_param_entry_value *src_val,
 
 const struct feature_param_ops feature_param_ops_uint = {
 	.set = feature_param_set_uint,
+	.free_value = feature_param_free_value_uint,
 	.stringify = feature_param_stringify_uint,
 	.is_equal = feature_param_is_equal_uint,
 	.copy = feature_param_copy_uint,
 };
 
 const struct feature_param_ops feature_param_ops_string = {
 	.set = feature_param_set_string,
+	.free_value = feature_param_free_value_string,
 	.stringify = feature_param_stringify_string,
 	.is_equal = feature_param_is_equal_string,
 	.copy = feature_param_copy_string,

lisa/_assets/kmodules/lisa/feature_params.h

@@ -106,6 +106,7 @@ struct feature_param {
 
 struct feature_param_ops {
 	struct feature_param_entry_value *(*set) (const char *, struct feature_param_entry *);
+	void (*free_value) (struct feature_param_entry_value *);
 	size_t (*stringify) (const struct feature_param_entry_value *, char *);
 	int (*is_equal) (const void *, const struct feature_param_entry_value *);
 	int (*copy) (const struct feature_param_entry_value *, struct feature_param_entry_value *);