On Thu, Jan 28, 2021 at 05:09:31PM +0000, Mike Leach wrote:
> Configurations are first activated, then when any coresight device is
> enabled, the active configurations are checked and any matching
> one is enabled.
>
> This patch provides the activation / enable API.
>
> Signed-off-by: Mike Leach <mike.leach@xxxxxxxxxx>
> ---
> .../hwtracing/coresight/coresight-config.h | 2 +
> .../hwtracing/coresight/coresight-syscfg.c | 127 ++++++++++++++++++
> .../hwtracing/coresight/coresight-syscfg.h | 10 +-
> include/linux/coresight.h | 2 +
> 4 files changed, 140 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-config.h b/drivers/hwtracing/coresight/coresight-config.h
> index 98380b496046..26396b70c826 100644
> --- a/drivers/hwtracing/coresight/coresight-config.h
> +++ b/drivers/hwtracing/coresight/coresight-config.h
> @@ -156,6 +156,7 @@ struct cscfg_config_feat_ref {
> * @presets: Array of preset values.
> * @id_ea: Extended attribute for perf configid value
> * @event_ea: Extended attribute for perf event value
> + * @active_cnt: ref count for activate on this configuration.
> */
> struct cscfg_config_desc {
> const char *name;
> @@ -168,6 +169,7 @@ struct cscfg_config_desc {
> const u64 *presets; /* nr_presets * nr_total_params */
> struct dev_ext_attribute *id_ea;
> struct dev_ext_attribute *event_ea;
> + atomic_t active_cnt;
> };
>
> /**
> diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
> index a070f135eca3..d79cf5b36758 100644
> --- a/drivers/hwtracing/coresight/coresight-syscfg.c
> +++ b/drivers/hwtracing/coresight/coresight-syscfg.c
> @@ -298,6 +298,7 @@ static int cscfg_load_config(struct cscfg_config_desc *cfg_desc)
> return err;
>
> list_add(&cfg_desc->item, &cscfg_mgr->data.config_desc_list);
> + atomic_set(&cfg_desc->active_cnt, 0);
> return 0;
> }
>
> @@ -477,6 +478,131 @@ void cscfg_unregister_csdev(struct coresight_device *csdev)
> }
> EXPORT_SYMBOL_GPL(cscfg_unregister_csdev);
>
> +void cscfg_csdev_reset_feats(struct coresight_device *csdev)
> +{
> + struct cscfg_feature_csdev *feat;
> +
> + mutex_lock(&cscfg_csdev_mutex);
> + if (list_empty(&csdev->feature_csdev_list))
> + goto unlock_exit;
> +
> + list_for_each_entry(feat, &csdev->feature_csdev_list, node)
> + cscfg_reset_feat(feat);
> +
> +unlock_exit:
> + mutex_unlock(&cscfg_csdev_mutex);
> +}
> +EXPORT_SYMBOL_GPL(cscfg_csdev_reset_feats);
> +
> +/**
> + * Mark a config descriptor as active.
> + * This will be seen when csdev devices are activated in the system.
> + *
> + * Selection by hash value - generated from the configuration name when it
> + * was loaded and added to the cs_etm/configurations file system for selection
> + * by perf.
> + *
> + * @cfg_hash: Hash value of the selected configuration name.
> + */
> +int cscfg_activate_config(unsigned long cfg_hash)
> +{
> + struct cscfg_config_desc *curr_item, *match_item = 0;
> +
> + mutex_lock(&cscfg_mutex);
> +
> + list_for_each_entry(curr_item, &cscfg_mgr->data.config_desc_list, item) {
> + if ((unsigned long)curr_item->id_ea->var == cfg_hash) {
> + match_item = curr_item;
> + atomic_inc(&cscfg_mgr->data.sys_active_cnt);
It would be nice to have a comment that mentions why this is needed. I had to
go look in patch 09 to see that it prevents a feature from being changed when
any configuration is active. And since patch 09 is the only place where
@sys_active_cnt is used, please move the declaration and handling of the
variable there.
> + break;
> + }
> + }
> + mutex_unlock(&cscfg_mutex);
> +
> + if (!match_item)
> + return -EINVAL;
> +
> + dev_dbg(to_device_cscfg(), "Activate config %s.\n", match_item->name);
> +
> + /* mark the descriptors as active so enable config will use them */
> + mutex_lock(&cscfg_csdev_mutex);
> + atomic_inc(&match_item->active_cnt);
What is ->active_cnt used for? I see it referenced in
cscfg_csdev_enable_active_config() but it doesn't do much other than to confirm
the configuration has been activated by someone.
There is also a chance that a caller would call cscfg_activate_config() once and
call cscfg_csdev_enable_active_config() multiple time, which would really create
problems. I would move the incrementation of sys_active_cnt within the mutex
hold in cscfg_csdev_enable_active_config() and get rid of ->active_cnt. If I am
correct we wouldn't need cscfg_activate_config() after that.
> + mutex_unlock(&cscfg_csdev_mutex);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(cscfg_activate_config);
> +
> +void cscfg_deactivate_config(unsigned long cfg_hash)
I'm fine with either cfg_hash or id_hash, but not both.
> +{
> + struct cscfg_config_desc *curr_item, *match_item = 0;
> +
> + mutex_lock(&cscfg_mutex);
> +
> + list_for_each_entry(curr_item, &cscfg_mgr->data.config_desc_list, item) {
> + if ((unsigned long)curr_item->id_ea->var == cfg_hash) {
> + match_item = curr_item;
> + break;
> + }
> + }
> + mutex_unlock(&cscfg_mutex);
> + if (!match_item)
> + return;
> +
> + dev_dbg(to_device_cscfg(), "Deactivate config %s.\n", match_item->name);
> +
> + mutex_lock(&cscfg_csdev_mutex);
> + atomic_dec(&match_item->active_cnt);
> + mutex_unlock(&cscfg_csdev_mutex);
> +
> + atomic_dec(&cscfg_mgr->data.sys_active_cnt);
> +}
> +EXPORT_SYMBOL_GPL(cscfg_deactivate_config);
> +
> +/* Find and program any active config for the supplied device.*/
> +int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
> + unsigned long id_hash, int preset)
> +{
> + struct cscfg_config_csdev *cfg = NULL, *item;
> + const struct cscfg_config_desc *desc;
> + int err = 0;
> +
> + /* quickly check global count */
> + if (!atomic_read(&cscfg_mgr->data.sys_active_cnt))
> + return 0;
> +
> + mutex_lock(&cscfg_csdev_mutex);
> + list_for_each_entry(item, &csdev->config_csdev_list, node) {
> + desc = item->desc;
> + if ((atomic_read(&desc->active_cnt)) &&
> + ((unsigned long)desc->id_ea->var == id_hash)) {
> + cfg = item;
> + break;
> + }
> + }
> + if (cfg) {
> + err = cscfg_csdev_enable_config(cfg, preset);
> + if (!err)
> + csdev->active_cfg_ctxt = (void *)cfg;
> + }
> + mutex_unlock(&cscfg_csdev_mutex);
> + return err;
> +}
> +EXPORT_SYMBOL_GPL(cscfg_csdev_enable_active_config);
> +
> +/* save and disable the active config for the device */
> +void cscfg_csdev_disable_active_config(struct coresight_device *csdev)
> +{
> + struct cscfg_config_csdev *cfg;
> +
> + mutex_lock(&cscfg_csdev_mutex);
> + cfg = (struct cscfg_config_csdev *)csdev->active_cfg_ctxt;
> + if (cfg)
> + cscfg_csdev_disable_config(cfg);
> + mutex_unlock(&cscfg_csdev_mutex);
> +}
> +EXPORT_SYMBOL_GPL(cscfg_csdev_disable_active_config);
> +
> /* Initialise system configuration management device. */
>
> struct device *to_device_cscfg(void)
> @@ -546,6 +672,7 @@ int __init cscfg_init(void)
> INIT_LIST_HEAD(&cscfg_mgr->data.feat_desc_list);
> INIT_LIST_HEAD(&cscfg_mgr->data.config_desc_list);
> cscfg_mgr->data.nr_csdev = 0;
> + atomic_set(&cscfg_mgr->data.sys_active_cnt, 0);
>
> dev_info(to_device_cscfg(), "CoreSight Configuration manager initialised");
> return 0;
> diff --git a/drivers/hwtracing/coresight/coresight-syscfg.h b/drivers/hwtracing/coresight/coresight-syscfg.h
> index ebf5e1491d86..301e26e1e98f 100644
> --- a/drivers/hwtracing/coresight/coresight-syscfg.h
> +++ b/drivers/hwtracing/coresight/coresight-syscfg.h
> @@ -17,13 +17,15 @@
> * @csdev_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.
> - * @nr_csdev: Number of registered devices with the cscfg system
> + * @nr_csdev: Number of registered devices with the cscfg system
> + * @sys_active_cnt: Total number of active config descriptor references.
> */
> struct cscfg_api_data {
> struct list_head csdev_desc_list;
> struct list_head feat_desc_list;
> struct list_head config_desc_list;
> int nr_csdev;
> + atomic_t sys_active_cnt;
> };
>
> /**
> @@ -53,6 +55,12 @@ int cscfg_register_csdev(struct coresight_device *csdev,
> struct cscfg_match_desc *info,
> struct cscfg_csdev_feat_ops *ops);
> void cscfg_unregister_csdev(struct coresight_device *csdev);
> +int cscfg_activate_config(unsigned long cfg_hash);
> +void cscfg_deactivate_config(unsigned long cfg_hash);
> +void cscfg_csdev_reset_feats(struct coresight_device *csdev);
> +int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
> + unsigned long id_hash, int preset);
> +void cscfg_csdev_disable_active_config(struct coresight_device *csdev);
>
> /**
> * System configuration manager device.
> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> index d0126ed326a6..3941854e8280 100644
> --- a/include/linux/coresight.h
> +++ b/include/linux/coresight.h
> @@ -221,6 +221,7 @@ struct coresight_sysfs_link {
> * @has_conns_grp: Have added a "connections" group for sysfs links.
> * @feature_csdev_list: List of complex feature programming added to the device.
> * @config_csdev_list: List of system configurations added to the device.
> + * @active_cfg_ctxt: Context information for current active congfig.
> */
> struct coresight_device {
> struct coresight_platform_data *pdata;
> @@ -245,6 +246,7 @@ struct coresight_device {
> /* system configuration and feature lists */
> struct list_head feature_csdev_list;
> struct list_head config_csdev_list;
> + void *active_cfg_ctxt;
> };
>
> /*
> --
> 2.17.1
>
