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coresight: syscfg: Update load API for config loadable modules

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CoreSight configurations and features can be added as kernel loadable
modules. This patch updates the load owner API to ensure that the module
cannot be unloaded either:
1) if the config it supplies is in use
2) if the module is not the last in the load order list.

Signed-off-by: Mike Leach <mike.leach@linaro.org>
Link: https://lore.kernel.org/r/20211124200038.28662-4-mike.leach@linaro.org
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
This commit is contained in:
Mike Leach 2021-11-24 20:00:35 +00:00 committed by Mathieu Poirier
parent 02bd588e12
commit eb2ec49606
2 changed files with 39 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
drivers/hwtracing/coresight/coresight-syscfg.c
View File

@ -368,6 +368,26 @@ int cscfg_update_feat_param_val(struct cscfg_feature_desc *feat_desc,
return err;
}
/*
* Conditionally up reference count on owner to prevent unload.
*
* module loaded configs need to be locked in to prevent premature unload.
*/
static int cscfg_owner_get(struct cscfg_load_owner_info *owner_info)
{
if ((owner_info->type == CSCFG_OWNER_MODULE) &&
(!try_module_get(owner_info->owner_handle)))
return -EINVAL;
return 0;
}
/* conditionally lower ref count on an owner */
static void cscfg_owner_put(struct cscfg_load_owner_info *owner_info)
{
if (owner_info->type == CSCFG_OWNER_MODULE)
module_put(owner_info->owner_handle);
}
static void cscfg_remove_owned_csdev_configs(struct coresight_device *csdev, void *load_owner)
{
struct cscfg_config_csdev *config_csdev, *tmp;
@ -497,6 +517,14 @@ int cscfg_load_config_sets(struct cscfg_config_desc **config_descs,
/* add the load owner to the load order list */
list_add_tail(&owner_info->item, &cscfg_mgr->load_order_list);
if (!list_is_singular(&cscfg_mgr->load_order_list)) {
/* lock previous item in load order list */
err = cscfg_owner_get(list_prev_entry(owner_info, item));
if (err) {
cscfg_unload_owned_cfgs_feats(owner_info);
list_del(&owner_info->item);
}
}
exit_unlock:
mutex_unlock(&cscfg_mutex);
@ -547,7 +575,11 @@ int cscfg_unload_config_sets(struct cscfg_load_owner_info *owner_info)
cscfg_unload_owned_cfgs_feats(owner_info);
/* remove from load order list */
list_del(&load_list_item->item);
if (!list_is_singular(&cscfg_mgr->load_order_list)) {
/* unlock previous item in load order list */
cscfg_owner_put(list_prev_entry(owner_info, item));
}
list_del(&owner_info->item);
exit_unlock:
mutex_unlock(&cscfg_mutex);
@ -739,6 +771,10 @@ int cscfg_activate_config(unsigned long cfg_hash)
list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) {
if ((unsigned long)config_desc->event_ea->var == cfg_hash) {
/* must ensure that config cannot be unloaded in use */
err = cscfg_owner_get(config_desc->load_owner);
if (err)
break;
/*
* increment the global active count - control changes to
* active configurations
@ -779,6 +815,7 @@ void cscfg_deactivate_config(unsigned long cfg_hash)
if ((unsigned long)config_desc->event_ea->var == cfg_hash) {
atomic_dec(&config_desc->active_cnt);
atomic_dec(&cscfg_mgr->sys_active_cnt);
cscfg_owner_put(config_desc->load_owner);
dev_dbg(cscfg_device(), "Deactivate config %s.\n", config_desc->name);
break;
}

1
drivers/hwtracing/coresight/coresight-syscfg.h
View File

@ -61,6 +61,7 @@ struct cscfg_registered_csdev {
/* owner types for loading and unloading of config and feature sets */
enum cscfg_load_owner_type {
CSCFG_OWNER_PRELOAD,
CSCFG_OWNER_MODULE,
};
/**