coresight: configuration: Update API to introduce load owner concept

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2055405

commit da7000e
Author: Mike Leach <mike.leach@linaro.org>
Date:   Wed Nov 24 20:00:33 2021 +0000

    coresight: configuration: Update API to introduce load owner concept

    Update the existing load API to introduce a "load owner" concept.

    This allows the tracking of the loaded configurations and features against
    the loading owner type, to allow later unload according to owner.

    A list of loaded configurations by owner is created.

    The load owner infrastructure will be used in following patches
    to implement dynanic load and unload, alongside dependency tracking.

    Signed-off-by: Mike Leach <mike.leach@linaro.org>
    Link: https://lore.kernel.org/r/20211124200038.28662-2-mike.leach@linaro.org
    Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

Signed-off-by: Jeremy Linton <jlinton@redhat.com>

Author: jlinton

drivers/hwtracing/coresight/coresight-cfg-preload.c

@@ -24,8 +24,13 @@ static struct cscfg_config_desc *preload_cfgs[] = {
 	NULL
 };
 
+static struct cscfg_load_owner_info preload_owner = {
+	.type = CSCFG_OWNER_PRELOAD,
+};
+
 /* preload called on initialisation */
-int cscfg_preload(void)
+int cscfg_preload(void *owner_handle)
 {
-	return cscfg_load_config_sets(preload_cfgs, preload_feats);
+	preload_owner.owner_handle = owner_handle;
+	return cscfg_load_config_sets(preload_cfgs, preload_feats, &preload_owner);
 }

drivers/hwtracing/coresight/coresight-config.h

@@ -97,6 +97,7 @@ struct cscfg_regval_desc {
  * @params_desc: array of parameters used.
  * @nr_regs:	 number of registers used.
  * @regs_desc:	 array of registers used.
+ * @load_owner:	 handle to load owner for dynamic load and unload of features.
  */
 struct cscfg_feature_desc {
 	const char *name;
@@ -107,6 +108,7 @@ struct cscfg_feature_desc {
 	struct cscfg_parameter_desc *params_desc;
 	int nr_regs;
 	struct cscfg_regval_desc *regs_desc;
+	void *load_owner;
 };
 
 /**
@@ -128,7 +130,7 @@ struct cscfg_feature_desc {
  * @presets:		Array of preset values.
  * @event_ea:		Extended attribute for perf event value
  * @active_cnt:		ref count for activate on this configuration.
- *
+ * @load_owner:		handle to load owner for dynamic load and unload of configs.
  */
 struct cscfg_config_desc {
 	const char *name;
@@ -141,6 +143,7 @@ struct cscfg_config_desc {
 	const u64 *presets; /* nr_presets * nr_total_params */
 	struct dev_ext_attribute *event_ea;
 	atomic_t active_cnt;
+	void *load_owner;
 };
 
 /**

drivers/hwtracing/coresight/coresight-syscfg.c

@@ -361,13 +361,22 @@ int cscfg_update_feat_param_val(struct cscfg_feature_desc *feat_desc,
  * descriptors and load into the system.
  * Features are loaded first to ensure configuration dependencies can be met.
  *
+ * To facilitate dynamic loading and unloading, features and configurations
+ * have a "load_owner", to allow later unload by the same owner. An owner may
+ * be a loadable module or configuration dynamically created via configfs.
+ * As later loaded configurations can use earlier loaded features, creating load
+ * dependencies, a load order list is maintained. Unload is strictly in the
+ * reverse order to load.
+ *
  * @config_descs: 0 terminated array of configuration descriptors.
  * @feat_descs:   0 terminated array of feature descriptors.
+ * @owner_info:	  Information on the owner of this set.
  */
 int cscfg_load_config_sets(struct cscfg_config_desc **config_descs,
-			   struct cscfg_feature_desc **feat_descs)
+			   struct cscfg_feature_desc **feat_descs,
+			   struct cscfg_load_owner_info *owner_info)
 {
-	int err, i = 0;
+	int err = 0, i = 0;
 
 	mutex_lock(&cscfg_mutex);
 
@@ -382,6 +391,7 @@ int cscfg_load_config_sets(struct cscfg_config_desc **config_descs,
 				       feat_descs[i]->name);
 				goto exit_unlock;
 			}
+			feat_descs[i]->load_owner = owner_info;
 			i++;
 		}
 	}
@@ -398,10 +408,14 @@ int cscfg_load_config_sets(struct cscfg_config_desc **config_descs,
 				       config_descs[i]->name);
 				goto exit_unlock;
 			}
+			config_descs[i]->load_owner = owner_info;
 			i++;
 		}
 	}
 
+	/* add the load owner to the load order list */
+	list_add_tail(&owner_info->item, &cscfg_mgr->load_order_list);
+
 exit_unlock:
 	mutex_unlock(&cscfg_mutex);
 	return err;
@@ -827,10 +841,11 @@ int __init cscfg_init(void)
 	INIT_LIST_HEAD(&cscfg_mgr->csdev_desc_list);
 	INIT_LIST_HEAD(&cscfg_mgr->feat_desc_list);
 	INIT_LIST_HEAD(&cscfg_mgr->config_desc_list);
+	INIT_LIST_HEAD(&cscfg_mgr->load_order_list);
 	atomic_set(&cscfg_mgr->sys_active_cnt, 0);
 
 	/* preload built-in configurations */
-	err = cscfg_preload();
+	err = cscfg_preload(THIS_MODULE);
 	if (err)
 		goto exit_err;
 

drivers/hwtracing/coresight/coresight-syscfg.h

@@ -25,6 +25,7 @@
  * @csdev_desc_list:	List of coresight devices registered with the configuration manager.
  * @feat_desc_list:	List of feature descriptors to load into registered devices.
  * @config_desc_list:	List of system configuration descriptors to load into registered devices.
+ * @load_order_list:    Ordered list of owners for dynamically loaded configurations.
  * @sys_active_cnt:	Total number of active config descriptor references.
  * @cfgfs_subsys:	configfs subsystem used to manage configurations.
  */
@@ -33,6 +34,7 @@ struct cscfg_manager {
 	struct list_head csdev_desc_list;
 	struct list_head feat_desc_list;
 	struct list_head config_desc_list;
+	struct list_head load_order_list;
 	atomic_t sys_active_cnt;
 	struct configfs_subsystem cfgfs_subsys;
 };
@@ -56,18 +58,41 @@ struct cscfg_registered_csdev {
 	struct list_head item;
 };
 
+/* owner types for loading and unloading of config and feature sets */
+enum cscfg_load_owner_type {
+	CSCFG_OWNER_PRELOAD,
+};
+
+/**
+ * Load item - item to add to the load order list allowing dynamic load and
+ *             unload of configurations and features. Caller loading a config
+ *	       set provides a context handle for unload. API ensures that
+ *	       items unloaded strictly in reverse order from load to ensure
+ *	       dependencies are respected.
+ *
+ * @item:		list entry for load order list.
+ * @type:		type of owner - allows interpretation of owner_handle.
+ * @owner_handle:	load context - handle for owner of loaded configs.
+ */
+struct cscfg_load_owner_info {
+	struct list_head item;
+	int type;
+	void *owner_handle;
+};
+
 /* internal core operations for cscfg */
 int __init cscfg_init(void);
 void cscfg_exit(void);
-int cscfg_preload(void);
+int cscfg_preload(void *owner_handle);
 const struct cscfg_feature_desc *cscfg_get_named_feat_desc(const char *name);
 int cscfg_update_feat_param_val(struct cscfg_feature_desc *feat_desc,
 				int param_idx, u64 value);
 
 
 /* syscfg manager external API */
 int cscfg_load_config_sets(struct cscfg_config_desc **cfg_descs,
-			   struct cscfg_feature_desc **feat_descs);
+			   struct cscfg_feature_desc **feat_descs,
+			   struct cscfg_load_owner_info *owner_info);
 int cscfg_register_csdev(struct coresight_device *csdev, u32 match_flags,
 			 struct cscfg_csdev_feat_ops *ops);
 void cscfg_unregister_csdev(struct coresight_device *csdev);