From: Mathieu Poirier <mathieu.poirier@linaro.org>
To: Mike Leach <mike.leach@linaro.org>
Cc: coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
suzuki.poulose@arm.com, leo.yan@linaro.org
Subject: Re: [RFC PATCH 2/8] coresight: syscfg: Update load API for config loadable modules
Date: Mon, 17 May 2021 11:38:36 -0600 [thread overview]
Message-ID: <20210517173836.GC498571@xps15> (raw)
In-Reply-To: <20210512211752.4103-3-mike.leach@linaro.org>
On Wed, May 12, 2021 at 10:17:46PM +0100, Mike Leach wrote:
> 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:-
Please remove the '-'. It is not a big issue but you can be sure the various
patch robots will complain. With that:
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> 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>
> ---
> .../hwtracing/coresight/coresight-syscfg.c | 39 ++++++++++++++++++-
> .../hwtracing/coresight/coresight-syscfg.h | 1 +
> 2 files changed, 39 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
> index ab5ec43a9dad..26c1a244c2b1 100644
> --- a/drivers/hwtracing/coresight/coresight-syscfg.c
> +++ b/drivers/hwtracing/coresight/coresight-syscfg.c
> @@ -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);
> @@ -737,6 +769,10 @@ 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
> @@ -777,6 +813,7 @@ 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;
> }
> diff --git a/drivers/hwtracing/coresight/coresight-syscfg.h b/drivers/hwtracing/coresight/coresight-syscfg.h
> index e2b2bdab31aa..1da37874f70f 100644
> --- a/drivers/hwtracing/coresight/coresight-syscfg.h
> +++ b/drivers/hwtracing/coresight/coresight-syscfg.h
> @@ -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,
> };
>
> /**
> --
> 2.17.1
>
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next prev parent reply other threads:[~2021-05-17 17:40 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-12 21:17 [RFC PATCH 0/8] coresight: syscfg: dynamic load, resource management Mike Leach
2021-05-12 21:17 ` [RFC PATCH 1/8] coresight: syscfg: Update API to allow dynamic load and unload Mike Leach
2021-05-17 17:15 ` Mathieu Poirier
2021-05-17 17:27 ` Mathieu Poirier
2021-05-19 13:28 ` Mike Leach
2021-05-12 21:17 ` [RFC PATCH 2/8] coresight: syscfg: Update load API for config loadable modules Mike Leach
2021-05-17 17:38 ` Mathieu Poirier [this message]
2021-05-12 21:17 ` [RFC PATCH 3/8] coresight: syscfg: Example CoreSight configuration loadable module Mike Leach
2021-05-18 15:52 ` Mathieu Poirier
2021-05-18 16:38 ` Mike Leach
2021-05-18 21:15 ` Mathieu Poirier
2021-05-12 21:17 ` [RFC PATCH 4/8] coresight: configfs: Allow configfs to activate configuration Mike Leach
2021-05-18 19:36 ` Mathieu Poirier
2021-05-19 9:47 ` Mike Leach
2021-05-12 21:17 ` [RFC PATCH 5/8] coresight: syscfg: Add API to check and validate device resources Mike Leach
2021-05-21 17:56 ` Mathieu Poirier
2021-07-08 16:30 ` Mike Leach
2021-05-12 21:17 ` [RFC PATCH 6/8] coresight: etm4x: syscfg: Add resource management to etm4x Mike Leach
2021-05-26 17:51 ` Mathieu Poirier
2021-05-27 17:41 ` Mathieu Poirier
2021-05-28 16:17 ` Mathieu Poirier
2021-07-09 9:32 ` Mike Leach
2021-05-12 21:17 ` [RFC PATCH 7/8] coresight: etm4x: Update perf event resource handling Mike Leach
2021-05-12 21:17 ` [RFC PATCH 8/8] coresight: etm4x: Update configuration example Mike Leach
2021-05-13 15:56 ` [RFC PATCH 0/8] coresight: syscfg: dynamic load, resource management Mathieu Poirier
2021-05-13 16:53 ` Mike Leach
2021-05-14 1:35 ` Leo Yan
2021-05-18 18:31 ` Suzuki K Poulose
2021-05-19 9:43 ` Mike Leach
2021-05-19 15:37 ` Mathieu Poirier
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