Re: [PATCH v2 1/5] coresight: syscfg: Update API to allow dynamic load and unload

Good morning Mike,

On Tue, Oct 19, 2021 at 08:13:47PM +0100, Mike Leach wrote:

Update the load API to permit the runtime loading and unloading of new configurations and features.

On load, configurations and features are tagged with a "load owner" that is used to determine sets that were loaded together in a given API call.

To unload the API uses the load owner to unload all elements previously loaded by that owner.

The API also records the order in which different owners loaded their elements into the system. Later loading configurations can use previously loaded features, creating load dependencies. Therefore unload is enforced strictly in the reverse order to load.

A load owner will be an additional loadable module, or a configuration created or loaded via configfs.

Signed-off-by: Mike Leach mike.leach@linaro.org Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org

I couldn't remember the patchset so I started reviewing it again from scratch.

I didn't find any flaws in the code. On the flip side I think there is two things happening here: 1) the addition of the owner concept and 2) the enhancement of the API to add/remove configurations/features.

Please consider splitting in two different patches. More comments tomorrow...

Thanks, Mathieu

---

.../coresight/coresight-cfg-preload.c | 9 +- .../hwtracing/coresight/coresight-config.h | 9 +- .../coresight/coresight-syscfg-configfs.c | 20 +++ .../coresight/coresight-syscfg-configfs.h | 2 + .../hwtracing/coresight/coresight-syscfg.c | 154 +++++++++++++++++- .../hwtracing/coresight/coresight-syscfg.h | 30 +++- 6 files changed, 216 insertions(+), 8 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-cfg-preload.c b/drivers/hwtracing/coresight/coresight-cfg-preload.c index 751af3710d56..e237a4edfa09 100644 --- a/drivers/hwtracing/coresight/coresight-cfg-preload.c +++ b/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);

} diff --git a/drivers/hwtracing/coresight/coresight-config.h b/drivers/hwtracing/coresight/coresight-config.h index 25eb6c632692..9bd44b940add 100644 --- a/drivers/hwtracing/coresight/coresight-config.h +++ b/drivers/hwtracing/coresight/coresight-config.h @@ -97,6 +97,8 @@ 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.
• • @fs_group: reference to configfs group for dynamic unload.
  */

struct cscfg_feature_desc { const char *name; @@ -107,6 +109,8 @@ struct cscfg_feature_desc { struct cscfg_parameter_desc *params_desc; int nr_regs; struct cscfg_regval_desc *regs_desc;

• void *load_owner;
• struct config_group *fs_group;

}; /** @@ -128,7 +132,8 @@ 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.
• • @fs_group: reference to configfs group for dynamic unload.
  */

struct cscfg_config_desc { const char *name; @@ -141,6 +146,8 @@ 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;
• struct config_group *fs_group;

}; /** diff --git a/drivers/hwtracing/coresight/coresight-syscfg-configfs.c b/drivers/hwtracing/coresight/coresight-syscfg-configfs.c index c547816b9000..345a62f1b728 100644 --- a/drivers/hwtracing/coresight/coresight-syscfg-configfs.c +++ b/drivers/hwtracing/coresight/coresight-syscfg-configfs.c @@ -334,9 +334,19 @@ int cscfg_configfs_add_config(struct cscfg_config_desc *config_desc) if (IS_ERR(new_group)) return PTR_ERR(new_group); err = configfs_register_group(&cscfg_configs_grp, new_group);

• if (!err)

• config_desc->fs_group = new_group;
  

  return err;

} +void cscfg_configfs_del_config(struct cscfg_config_desc *config_desc) +{

• if (config_desc->fs_group) {

• configfs_unregister_group(config_desc->fs_group);
  

• config_desc->fs_group = NULL;
  

• }

+}

static struct config_item_type cscfg_features_type = { .ct_owner = THIS_MODULE, }; @@ -358,9 +368,19 @@ int cscfg_configfs_add_feature(struct cscfg_feature_desc *feat_desc) if (IS_ERR(new_group)) return PTR_ERR(new_group); err = configfs_register_group(&cscfg_features_grp, new_group);

• if (!err)

• feat_desc->fs_group = new_group;
  

  return err;

} +void cscfg_configfs_del_feature(struct cscfg_feature_desc *feat_desc) +{

• if (feat_desc->fs_group) {

• configfs_unregister_group(feat_desc->fs_group);
  

• feat_desc->fs_group = NULL;
  

• }

+}

int cscfg_configfs_init(struct cscfg_manager *cscfg_mgr) { struct configfs_subsystem *subsys; diff --git a/drivers/hwtracing/coresight/coresight-syscfg-configfs.h b/drivers/hwtracing/coresight/coresight-syscfg-configfs.h index 7d6ffe35ca4c..ea1e54d29f7f 100644 --- a/drivers/hwtracing/coresight/coresight-syscfg-configfs.h +++ b/drivers/hwtracing/coresight/coresight-syscfg-configfs.h @@ -41,5 +41,7 @@ int cscfg_configfs_init(struct cscfg_manager *cscfg_mgr); void cscfg_configfs_release(struct cscfg_manager *cscfg_mgr); int cscfg_configfs_add_config(struct cscfg_config_desc *config_desc); int cscfg_configfs_add_feature(struct cscfg_feature_desc *feat_desc); +void cscfg_configfs_del_config(struct cscfg_config_desc *config_desc); +void cscfg_configfs_del_feature(struct cscfg_feature_desc *feat_desc); #endif /* CORESIGHT_SYSCFG_CONFIGFS_H */ diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c index fc0760f55c53..9bb0b0913a9a 100644 --- a/drivers/hwtracing/coresight/coresight-syscfg.c +++ b/drivers/hwtracing/coresight/coresight-syscfg.c @@ -249,6 +249,13 @@ static int cscfg_check_feat_for_cfg(struct cscfg_config_desc *config_desc) static int cscfg_load_feat(struct cscfg_feature_desc *feat_desc) { int err;

• struct cscfg_feature_desc *feat_desc_exist;
• /* new feature must have unique name */
• list_for_each_entry(feat_desc_exist, &cscfg_mgr->feat_desc_list, item) {

• if (!strcmp(feat_desc_exist->name, feat_desc->name))
  

• 	return -EEXIST;
  

• }

/* add feature to any matching registered devices */ err = cscfg_add_feat_to_csdevs(feat_desc); @@ -266,6 +273,13 @@ static int cscfg_load_feat(struct cscfg_feature_desc *feat_desc) static int cscfg_load_config(struct cscfg_config_desc *config_desc) { int err;

• struct cscfg_config_desc *config_desc_exist;
• /* new configuration must have a unique name */
• list_for_each_entry(config_desc_exist, &cscfg_mgr->config_desc_list, item) {

• if (!strcmp(config_desc_exist->name, config_desc->name))
  

• 	return -EEXIST;
  

• }

/* validate features are present */ err = cscfg_check_feat_for_cfg(config_desc); @@ -353,6 +367,72 @@ int cscfg_update_feat_param_val(struct cscfg_feature_desc *feat_desc, return err; } +static void cscfg_remove_owned_csdev_configs(struct coresight_device *csdev, void *load_owner) +{

• struct cscfg_config_csdev *config_csdev, *tmp;
• if (list_empty(&csdev->config_csdev_list))

• return;
  

• list_for_each_entry_safe(config_csdev, tmp, &csdev->config_csdev_list, node) {

• if (config_csdev->config_desc->load_owner == load_owner)
  

• 	list_del(&config_csdev->node);
  

• }

+}

+static void cscfg_remove_owned_csdev_features(struct coresight_device *csdev, void *load_owner) +{

• struct cscfg_feature_csdev *feat_csdev, *tmp;
• if (list_empty(&csdev->feature_csdev_list))

• return;
  

• list_for_each_entry_safe(feat_csdev, tmp, &csdev->feature_csdev_list, node) {

• if (feat_csdev->feat_desc->load_owner == load_owner)
  

• 	list_del(&feat_csdev->node);
  

• }

+}

+/*

• • removal is relatively easy - just remove from all lists, anything that
• • matches the owner. Memory for the descriptors will be managed by the owner,
• • memory for the csdev items is devm_ allocated with the individual csdev
• • devices.
• */

+static void cscfg_unload_owned_cfgs_feats(void *load_owner) +{

• struct cscfg_config_desc *config_desc, *cfg_tmp;
• struct cscfg_feature_desc *feat_desc, *feat_tmp;
• struct cscfg_registered_csdev *csdev_item;
• /* remove from each csdev instance feature and config lists */
• list_for_each_entry(csdev_item, &cscfg_mgr->csdev_desc_list, item) {

• /*
  

•  * for each csdev, check the loaded lists and remove if
  

•  * referenced descriptor is owned
  

•  */
  

• cscfg_remove_owned_csdev_configs(csdev_item->csdev, load_owner);
  

• cscfg_remove_owned_csdev_features(csdev_item->csdev, load_owner);
  

• }
• /* remove from the config descriptor lists */
• list_for_each_entry_safe(config_desc, cfg_tmp, &cscfg_mgr->config_desc_list, item) {

• if (config_desc->load_owner == load_owner) {
  

• 	cscfg_configfs_del_config(config_desc);
  

• 	etm_perf_del_symlink_cscfg(config_desc);
  

• 	list_del(&config_desc->item);
  

• }
  

• }
• /* remove from the feature descriptor lists */
• list_for_each_entry_safe(feat_desc, feat_tmp, &cscfg_mgr->feat_desc_list, item) {

• if (feat_desc->load_owner == load_owner) {
  

• 	cscfg_configfs_del_feature(feat_desc);
  

• 	list_del(&feat_desc->item);
  

• }
  

• }

+}

/**

• cscfg_load_config_sets - API function to load feature and config sets.

@@ -360,13 +440,22 @@ 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); @@ -379,8 +468,10 @@ int cscfg_load_config_sets(struct cscfg_config_desc **config_descs, if (err) { pr_err("coresight-syscfg: Failed to load feature %s\n", feat_descs[i]->name);

• 		cscfg_unload_owned_cfgs_feats(owner_info);
  	goto exit_unlock;
  }
  

• 	feat_descs[i]->load_owner = owner_info;
  i++;
  

  } }

@@ -395,18 +486,74 @@ int cscfg_load_config_sets(struct cscfg_config_desc **config_descs, if (err) { pr_err("coresight-syscfg: Failed to load configuration %s\n", config_descs[i]->name);

• 		cscfg_unload_owned_cfgs_feats(owner_info);
  	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; } EXPORT_SYMBOL_GPL(cscfg_load_config_sets); +/**

• • cscfg_unload_config_sets - unload a set of configurations by owner.
• • Dynamic unload of configuration and feature sets is done on the basis of
• • the load owner of that set. Later loaded configurations can depend on
• • features loaded earlier.
• • Therefore, unload is only possible if:-
• • 1. no configurations are active.
• • 2. the set being unloaded was the last to be loaded to maintain dependencies.
• • @owner_info: Information on owner for set being unloaded.
• */

+int cscfg_unload_config_sets(struct cscfg_load_owner_info *owner_info) +{

• int err = 0;
• struct cscfg_load_owner_info *load_list_item = NULL;
• mutex_lock(&cscfg_mutex);
• /* cannot unload if anything is active */
• if (atomic_read(&cscfg_mgr->sys_active_cnt)) {

• err = -EBUSY;
  

• goto exit_unlock;
  

• }
• /* cannot unload if not last loaded in load order */
• if (!list_empty(&cscfg_mgr->load_order_list)) {

• load_list_item = list_last_entry(&cscfg_mgr->load_order_list,
  

• 				 struct cscfg_load_owner_info, item);
  

• if (load_list_item != owner_info)
  

• 	load_list_item = NULL;
  

• }
• if (!load_list_item) {

• err = -EINVAL;
  

• goto exit_unlock;
  

• }
• /* unload all belonging to load_owner */
• cscfg_unload_owned_cfgs_feats(owner_info);
• /* remove from load order list */
• list_del(&load_list_item->item);

+exit_unlock:

• mutex_unlock(&cscfg_mutex);
• return err;

+} +EXPORT_SYMBOL_GPL(cscfg_unload_config_sets);

/* Handle coresight device registration and add configs and features to devices */ /* iterate through config lists and load matching configs to device */ @@ -826,10 +973,11 @@ 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;

diff --git a/drivers/hwtracing/coresight/coresight-syscfg.h b/drivers/hwtracing/coresight/coresight-syscfg.h index 8d018efd6ead..e2b2bdab31aa 100644 --- a/drivers/hwtracing/coresight/coresight-syscfg.h +++ b/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;

}; @@ -56,10 +58,32 @@ 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); @@ -67,7 +91,9 @@ int cscfg_update_feat_param_val(struct cscfg_feature_desc *feat_desc, /* 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_unload_config_sets(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); -- 2.17.1