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[68.147.0.187]) by smtp.gmail.com with ESMTPSA id f31sm27543239pgm.1.2021.07.20.11.07.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Jul 2021 11:07:48 -0700 (PDT) Date: Tue, 20 Jul 2021 12:07:46 -0600 From: Mathieu Poirier To: Mike Leach Cc: linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org, suzuki.poulose@arm.com, leo.yan@linaro.org, alexander.shishkin@linux.intel.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v8 05/10] coresight: syscfg: Add API to activate and enable configurations Message-ID: <20210720180746.GB2301883@p14s> References: <20210707133003.5414-1-mike.leach@linaro.org> <20210707133003.5414-6-mike.leach@linaro.org> <20210720174106.GA2301883@p14s> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210720174106.GA2301883@p14s> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210720_110755_762601_0740F416 X-CRM114-Status: GOOD ( 48.99 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jul 20, 2021 at 11:41:06AM -0600, Mathieu Poirier wrote: > On Wed, Jul 07, 2021 at 02:29:58PM +0100, 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 > > Reviewed-by: Mathieu Poirier > > --- > > .../hwtracing/coresight/coresight-config.h | 2 + > > .../hwtracing/coresight/coresight-syscfg.c | 197 ++++++++++++++++++ > > .../hwtracing/coresight/coresight-syscfg.h | 8 + > > include/linux/coresight.h | 4 + > > 4 files changed, 211 insertions(+) > > > > diff --git a/drivers/hwtracing/coresight/coresight-config.h b/drivers/hwtracing/coresight/coresight-config.h > > index 0667581822c1..25eb6c632692 100644 > > --- a/drivers/hwtracing/coresight/coresight-config.h > > +++ b/drivers/hwtracing/coresight/coresight-config.h > > @@ -127,6 +127,7 @@ struct cscfg_feature_desc { > > * @nr_total_params: Sum of all parameters declared by used features > > * @presets: Array of preset values. > > * @event_ea: Extended attribute for perf event value > > + * @active_cnt: ref count for activate on this configuration. > > * > > */ > > struct cscfg_config_desc { > > @@ -139,6 +140,7 @@ struct cscfg_config_desc { > > int nr_total_params; > > const u64 *presets; /* nr_presets * nr_total_params */ > > 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 b93f2b4a777e..4e9804875a9b 100644 > > --- a/drivers/hwtracing/coresight/coresight-syscfg.c > > +++ b/drivers/hwtracing/coresight/coresight-syscfg.c > > @@ -282,6 +282,7 @@ static int cscfg_load_config(struct cscfg_config_desc *config_desc) > > return err; > > > > list_add(&config_desc->item, &cscfg_mgr->config_desc_list); > > + atomic_set(&config_desc->active_cnt, 0); > > return 0; > > } > > > > @@ -468,6 +469,201 @@ void cscfg_unregister_csdev(struct coresight_device *csdev) > > } > > EXPORT_SYMBOL_GPL(cscfg_unregister_csdev); > > > > +/** > > + * cscfg_csdev_reset_feats - reset features for a CoreSight device. > > + * > > + * Resets all parameters and register values for any features loaded > > + * into @csdev to their default values. > > + * > > + * @csdev: The CoreSight device. > > + */ > > +void cscfg_csdev_reset_feats(struct coresight_device *csdev) > > +{ > > + struct cscfg_feature_csdev *feat_csdev; > > + unsigned long flags; > > + > > + spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags); > > + if (list_empty(&csdev->feature_csdev_list)) > > + goto unlock_exit; > > + > > + list_for_each_entry(feat_csdev, &csdev->feature_csdev_list, node) > > + cscfg_reset_feat(feat_csdev); > > + > > +unlock_exit: > > + spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags); > > +} > > +EXPORT_SYMBOL_GPL(cscfg_csdev_reset_feats); > > + > > +/** > > + * cscfg_activate_config - Mark a configuration descriptor as active. > > + * > > + * This will be seen when csdev devices are enabled in the system. > > + * Only activated configurations can be enabled on individual devices. > > + * Activation protects the configuration from alteration or removal while > > + * active. > > + * > > + * 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. > > + * > > + * Increments the configuration descriptor active count and the global active > > + * count. > > + * > > + * @cfg_hash: Hash value of the selected configuration name. > > + */ > > +int cscfg_activate_config(unsigned long cfg_hash) > > +{ > > + struct cscfg_config_desc *config_desc; > > + int err = -EINVAL; > > + > > + mutex_lock(&cscfg_mutex); > > + > > + list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) { > > + if ((unsigned long)config_desc->event_ea->var == cfg_hash) { > > + /* > > + * increment the global active count - control changes to > > + * active configurations > > + */ > > + atomic_inc(&cscfg_mgr->sys_active_cnt); > > + > > + /* > > + * mark the descriptor as active so enable config on a > > + * device instance will use it > > + */ > > + atomic_inc(&config_desc->active_cnt); > > + > > + err = 0; > > + dev_dbg(cscfg_device(), "Activate config %s.\n", config_desc->name); > > + break; > > + } > > + } > > + mutex_unlock(&cscfg_mutex); > > + > > + return err; > > +} > > +EXPORT_SYMBOL_GPL(cscfg_activate_config); > > + > > +/** > > + * cscfg_deactivate_config - Mark a config descriptor as inactive. > > + * > > + * Decrement the configuration and global active counts. > > + * > > + * @cfg_hash: Hash value of the selected configuration name. > > + */ > > +void cscfg_deactivate_config(unsigned long cfg_hash) > > +{ > > + struct cscfg_config_desc *config_desc; > > + > > + mutex_lock(&cscfg_mutex); > > + > > + list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) { > > + if ((unsigned long)config_desc->event_ea->var == cfg_hash) { > > + atomic_dec(&config_desc->active_cnt); > > + atomic_dec(&cscfg_mgr->sys_active_cnt); > > + dev_dbg(cscfg_device(), "Deactivate config %s.\n", config_desc->name); > > + break; > > + } > > + } > > + mutex_unlock(&cscfg_mutex); > > +} > > +EXPORT_SYMBOL_GPL(cscfg_deactivate_config); > > + > > +/** > > + * cscfg_csdev_enable_active_config - Enable matching active configuration for device. > > + * > > + * Enables the configuration selected by @cfg_hash if the configuration is supported > > + * on the device and has been activated. > > + * > > + * If active and supported the CoreSight device @csdev will be programmed with the > > + * configuration, using @preset parameters. > > + * > > + * Should be called before driver hardware enable for the requested device, prior to > > + * programming and enabling the physical hardware. > > + * > > + * @csdev: CoreSight device to program. > > + * @cfg_hash: Selector for the configuration. > > + * @preset: Preset parameter values to use, 0 for current / default values. > > + */ > > +int cscfg_csdev_enable_active_config(struct coresight_device *csdev, > > + unsigned long cfg_hash, int preset) > > +{ > > + struct cscfg_config_csdev *config_csdev_active = NULL, *config_csdev_item; > > + const struct cscfg_config_desc *config_desc; > > + unsigned long flags; > > + int err = 0; > > + > > + /* quickly check global count */ > > + if (!atomic_read(&cscfg_mgr->sys_active_cnt)) > > + return 0; > > + > > + /* look for matching config - set in_enable flag if found */ > > + spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags); > > + list_for_each_entry(config_csdev_item, &csdev->config_csdev_list, node) { > > + config_desc = config_csdev_item->config_desc; > > + if ((atomic_read(&config_desc->active_cnt)) && > > + ((unsigned long)config_desc->event_ea->var == cfg_hash)) { > > + config_csdev_active = config_csdev_item; > > + csdev->cscfg_in_enable = true; > > + break; > > + } > > + } > > + spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags) > > In the previous revision the mutex wasn't dropped and > cscfg_csdev_enable_config() was called with the mutex held. Any reason for not > doing that with the spinlock implemenation? If anything it should be more > efficient because the spinlock is on a per csdev basis. It would also keep > things simple and avoid adding a new ->cscfg_in_enable field to the > coresight_device structure. That last point really concerns me - if holding the > spinlock is not possible than a new approach should be considered. I just read the rational for the above in the change summary... I will have to think further on this - more comments tomorrow. > > Thanks, > Mathieu > > > + > > + /* > > + * If found, attempt to enable and then set as enabled if no error > > + * and in enable flag still set. > > + */ > > + if (config_csdev_active) { > > + /* > > + * Call the generic routine that will program up the internal > > + * driver structures prior to programming up the hardware. > > + * This routine takes the driver spinlock saved in the configs. > > + */ > > + err = cscfg_csdev_enable_config(config_csdev_active, preset); > > + if (!err) { > > + /* > > + * Successful programming. re-check in_enable flag > > + * to avoid potential race with disable config. > > + */ > > + spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags); > > + if (csdev->cscfg_in_enable) > > + csdev->active_cscfg_ctxt = (void *)config_csdev_active; > > + csdev->cscfg_in_enable = false; > > + spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags); > > + } > > + } > > + return err; > > +} > > +EXPORT_SYMBOL_GPL(cscfg_csdev_enable_active_config); > > + > > +/** > > + * cscfg_csdev_disable_active_config - disable an active config on the device. > > + * > > + * Disables the active configuration on the CoreSight device @csdev. > > + * Disable will save the values of any registers marked in the configurations > > + * as save on disable. > > + * > > + * Should be called after driver hardware disable for the requested device, > > + * after disabling the physical hardware and reading back registers. > > + * > > + * @csdev: The CoreSight device. > > + */ > > +void cscfg_csdev_disable_active_config(struct coresight_device *csdev) > > +{ > > + struct cscfg_config_csdev *config_csdev; > > + unsigned long flags; > > + > > + spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags); > > + csdev->cscfg_in_enable = false; > > + config_csdev = (struct cscfg_config_csdev *)csdev->active_cscfg_ctxt; > > + csdev->active_cscfg_ctxt = NULL; > > + spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags); > > + > > + if (config_csdev) > > + cscfg_csdev_disable_config(config_csdev); > > +} > > +EXPORT_SYMBOL_GPL(cscfg_csdev_disable_active_config); > > + > > /* Initialise system configuration management device. */ > > > > struct device *cscfg_device(void) > > @@ -536,6 +732,7 @@ 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); > > + atomic_set(&cscfg_mgr->sys_active_cnt, 0); > > > > dev_info(cscfg_device(), "CoreSight Configuration manager initialised"); > > return 0; > > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.h b/drivers/hwtracing/coresight/coresight-syscfg.h > > index 5bcae3b374c6..a52775890670 100644 > > --- a/drivers/hwtracing/coresight/coresight-syscfg.h > > +++ b/drivers/hwtracing/coresight/coresight-syscfg.h > > @@ -24,12 +24,14 @@ > > * @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. > > + * @sys_active_cnt: Total number of active config descriptor references. > > */ > > struct cscfg_manager { > > struct device dev; > > struct list_head csdev_desc_list; > > struct list_head feat_desc_list; > > struct list_head config_desc_list; > > + atomic_t sys_active_cnt; > > }; > > > > /* get reference to dev in cscfg_manager */ > > @@ -61,5 +63,11 @@ int cscfg_load_config_sets(struct cscfg_config_desc **cfg_descs, > > 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); > > +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 cfg_hash, int preset); > > +void cscfg_csdev_disable_active_config(struct coresight_device *csdev); > > > > #endif /* CORESIGHT_SYSCFG_H */ > > diff --git a/include/linux/coresight.h b/include/linux/coresight.h > > index 16544ae2b532..e66e1a5fd803 100644 > > --- a/include/linux/coresight.h > > +++ b/include/linux/coresight.h > > @@ -223,6 +223,8 @@ struct coresight_sysfs_link { > > * @feature_csdev_list: List of complex feature programming added to the device. > > * @config_csdev_list: List of system configurations added to the device. > > * @cscfg_csdev_lock: Protect the lists of configurations and features. > > + * @active_cscfg_ctxt: Context information for current active system configuration. > > + * @cscfg_in_enable: Flag to indicate we are in the process of enabling. > > */ > > struct coresight_device { > > struct coresight_platform_data *pdata; > > @@ -248,6 +250,8 @@ struct coresight_device { > > struct list_head feature_csdev_list; > > struct list_head config_csdev_list; > > spinlock_t cscfg_csdev_lock; > > + void *active_cscfg_ctxt; > > + bool cscfg_in_enable; > > }; > > > > /* > > -- > > 2.17.1 > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel