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[68.147.0.187]) by smtp.gmail.com with ESMTPSA id h23sm7075870pfn.118.2021.02.25.13.20.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 Feb 2021 13:20:52 -0800 (PST) Date: Thu, 25 Feb 2021 14:20:50 -0700 From: Mathieu Poirier To: Mike Leach Cc: linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org, linux-doc@vger.kernel.org, suzuki.poulose@arm.com, yabinc@google.com, corbet@lwn.net, leo.yan@linaro.org, alexander.shishkin@linux.intel.com, tingwei@codeaurora.org, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 05/10] coresight: syscfg: Add API to activate and enable configurations Message-ID: <20210225212050.GA3567106@xps15> References: <20210128170936.9222-1-mike.leach@linaro.org> <20210128170936.9222-6-mike.leach@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210128170936.9222-6-mike.leach@linaro.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > --- > .../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 >