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Message-ID: <77d890a9-9927-da8e-1460-54513784683d@arm.com>
Date: Tue, 4 Apr 2023 10:21:27 +0100
From: Suzuki K Poulose <suzuki.poulose@....com>
To: James Clark <james.clark@....com>, coresight@...ts.linaro.org,
quic_jinlmao@...cinc.com, mike.leach@...aro.org
Cc: Mathieu Poirier <mathieu.poirier@...aro.org>,
Leo Yan <leo.yan@...aro.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
Alexandre Torgue <alexandre.torgue@...s.st.com>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-stm32@...md-mailman.stormreply.com
Subject: Re: [PATCH v3 13/13] coresight: Fix CTI module refcount leak by
making it a helper device
On 29/03/2023 12:53, James Clark wrote:
> The CTI module has some hard coded refcounting code that has a leak.
> For example running perf and then trying to unload it fails:
>
> perf record -e cs_etm// -a -- ls
> rmmod coresight_cti
>
> rmmod: ERROR: Module coresight_cti is in use
>
> The coresight core already handles references of devices in use, so by
> making CTI a normal helper device, we get working refcounting for free.
>
> Signed-off-by: James Clark <james.clark@....com>
> ---
> drivers/hwtracing/coresight/coresight-core.c | 99 ++++++-------------
> .../hwtracing/coresight/coresight-cti-core.c | 52 +++++-----
> .../hwtracing/coresight/coresight-cti-sysfs.c | 4 +-
> drivers/hwtracing/coresight/coresight-cti.h | 4 +-
> drivers/hwtracing/coresight/coresight-priv.h | 4 +-
> drivers/hwtracing/coresight/coresight-sysfs.c | 4 +
> include/linux/coresight.h | 30 +-----
> 7 files changed, 70 insertions(+), 127 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> index 65f5bd8516d8..458d91b4e23f 100644
> --- a/drivers/hwtracing/coresight/coresight-core.c
> +++ b/drivers/hwtracing/coresight/coresight-core.c
> @@ -254,60 +254,39 @@ void coresight_disclaim_device(struct coresight_device *csdev)
> }
> EXPORT_SYMBOL_GPL(coresight_disclaim_device);
>
> -/* enable or disable an associated CTI device of the supplied CS device */
> -static int
> -coresight_control_assoc_ectdev(struct coresight_device *csdev, bool enable)
> -{
> - int ect_ret = 0;
> - struct coresight_device *ect_csdev = csdev->ect_dev;
> - struct module *mod;
> -
> - if (!ect_csdev)
> - return 0;
> - if ((!ect_ops(ect_csdev)->enable) || (!ect_ops(ect_csdev)->disable))
> - return 0;
> -
> - mod = ect_csdev->dev.parent->driver->owner;
> - if (enable) {
> - if (try_module_get(mod)) {
> - ect_ret = ect_ops(ect_csdev)->enable(ect_csdev);
> - if (ect_ret) {
> - module_put(mod);
> - } else {
> - get_device(ect_csdev->dev.parent);
> - csdev->ect_enabled = true;
> - }
> - } else
> - ect_ret = -ENODEV;
> - } else {
> - if (csdev->ect_enabled) {
> - ect_ret = ect_ops(ect_csdev)->disable(ect_csdev);
> - put_device(ect_csdev->dev.parent);
> - module_put(mod);
> - csdev->ect_enabled = false;
> - }
> - }
> -
> - /* output warning if ECT enable is preventing trace operation */
> - if (ect_ret)
> - dev_info(&csdev->dev, "Associated ECT device (%s) %s failed\n",
> - dev_name(&ect_csdev->dev),
> - enable ? "enable" : "disable");
> - return ect_ret;
> -}
> -
> /*
> - * Set the associated ect / cti device while holding the coresight_mutex
> + * Add a helper as an output device while holding the coresight_mutex
> * to avoid a race with coresight_enable that may try to use this value.
> */
> -void coresight_set_assoc_ectdev_mutex(struct coresight_device *csdev,
> - struct coresight_device *ect_csdev)
> +void coresight_add_helper_mutex(struct coresight_device *csdev,
> + struct coresight_device *helper)
minor nit: It may be a good idea to rename this, in line with the
kernel naming convention :
coresight_add_helper_unlocked()
Or if this is the only variant, it is OK to leave it as :
coresight_add_helper()
with a big fat comment in the function description to indicate
that it takes the mutex and may be even add a :
might_sleep() and lockdep_assert_not_held(&coresight_mutex);
in the function.
> {
> + int i;
> + struct coresight_connection conn = {};
> +
> mutex_lock(&coresight_mutex);
> - csdev->ect_dev = ect_csdev;
> + conn.dest_fwnode = fwnode_handle_get(dev_fwnode(&helper->dev));
> + conn.dest_dev = helper;
> + conn.dest_port = conn.src_port = -1;
> + conn.src_dev = csdev;
> +
> + /*
> + * Check for duplicates because this is called every time a helper
> + * device is re-loaded. Existing connections will get re-linked
> + * automatically.
> + */
Thanks for adding this comment here. It does look like the already added
output connection to the "origin" device would automatically resolve the
connection and add in the "in-connection" to the CTI device.
> + for (i = 0; i < csdev->pdata->nr_outconns; ++i)
> + if (csdev->pdata->out_conns[i]->dest_fwnode == conn.dest_fwnode)
> + goto unlock;
> +
> + coresight_add_out_conn(csdev->dev.parent, csdev->pdata, &conn);
This makes me wonder if we should return the new connection in
coresight_add_out_conn() in case of success, rather than assuming the
last one (which is always the case though.).
i.e.,
new_conn = coresight_add_out_conn(...)
if (new_conn)
coresight_add_in_conn(new_conn);
> + coresight_add_in_conn(
> + csdev->pdata->out_conns[csdev->pdata->nr_outconns - 1]);
> +
> +unlock:
> mutex_unlock(&coresight_mutex);
> }
> -EXPORT_SYMBOL_GPL(coresight_set_assoc_ectdev_mutex);
> +EXPORT_SYMBOL_GPL(coresight_add_helper_mutex);
>
> static int coresight_enable_sink(struct coresight_device *csdev,
> enum cs_mode mode, void *data)
> @@ -321,12 +300,8 @@ static int coresight_enable_sink(struct coresight_device *csdev,
> if (!sink_ops(csdev)->enable)
> return -EINVAL;
>
> - ret = coresight_control_assoc_ectdev(csdev, true);
> - if (ret)
> - return ret;
> ret = sink_ops(csdev)->enable(csdev, mode, data);
> if (ret) {
> - coresight_control_assoc_ectdev(csdev, false);
> return ret;
> }
> csdev->enable = true;
> @@ -344,7 +319,6 @@ static void coresight_disable_sink(struct coresight_device *csdev)
> ret = sink_ops(csdev)->disable(csdev);
> if (ret)
> return;
> - coresight_control_assoc_ectdev(csdev, false);
> csdev->enable = false;
> }
>
> @@ -369,17 +343,11 @@ static int coresight_enable_link(struct coresight_device *csdev,
> return PTR_ERR(outconn);
>
> if (link_ops(csdev)->enable) {
> - ret = coresight_control_assoc_ectdev(csdev, true);
> - if (!ret) {
> - ret = link_ops(csdev)->enable(csdev, inconn, outconn);
> - if (ret)
> - coresight_control_assoc_ectdev(csdev, false);
> - }
> + ret = link_ops(csdev)->enable(csdev, inconn, outconn);
> + if (!ret)
> + csdev->enable = true;
> }
>
> - if (!ret)
> - csdev->enable = true;
> -
> return ret;
> }
>
> @@ -400,7 +368,6 @@ static void coresight_disable_link(struct coresight_device *csdev,
>
> if (link_ops(csdev)->disable) {
> link_ops(csdev)->disable(csdev, inconn, outconn);
> - coresight_control_assoc_ectdev(csdev, false);
> }
>
> if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG) {
> @@ -428,14 +395,9 @@ int coresight_enable_source(struct coresight_device *csdev, void *data,
>
> if (!csdev->enable) {
> if (source_ops(csdev)->enable) {
> - ret = coresight_control_assoc_ectdev(csdev, true);
> - if (ret)
> - return ret;
> ret = source_ops(csdev)->enable(csdev, data, mode);
> - if (ret) {
> - coresight_control_assoc_ectdev(csdev, false);
> + if (ret)
> return ret;
> - }
> }
> csdev->enable = true;
> }
> @@ -499,7 +461,6 @@ bool coresight_disable_source(struct coresight_device *csdev, void *data)
> if (atomic_dec_return(&csdev->refcnt) == 0) {
> if (source_ops(csdev)->disable)
> source_ops(csdev)->disable(csdev, data);
> - coresight_control_assoc_ectdev(csdev, false);
> coresight_disable_helpers(csdev);
> csdev->enable = false;
> }
> diff --git a/drivers/hwtracing/coresight/coresight-cti-core.c b/drivers/hwtracing/coresight/coresight-cti-core.c
> index 277c890a1f1f..db7a2212ec18 100644
> --- a/drivers/hwtracing/coresight/coresight-cti-core.c
> +++ b/drivers/hwtracing/coresight/coresight-cti-core.c
> @@ -555,7 +555,10 @@ static void cti_add_assoc_to_csdev(struct coresight_device *csdev)
> mutex_lock(&ect_mutex);
>
> /* exit if current is an ECT device.*/
> - if ((csdev->type == CORESIGHT_DEV_TYPE_ECT) || list_empty(&ect_net))
> + if ((csdev->type == CORESIGHT_DEV_TYPE_HELPER &&
> + csdev->subtype.helper_subtype ==
> + CORESIGHT_DEV_SUBTYPE_HELPER_ECT_CTI) ||
> + list_empty(&ect_net))
> goto cti_add_done;
>
> /* if we didn't find the csdev previously we used the fwnode name */
> @@ -571,8 +574,7 @@ static void cti_add_assoc_to_csdev(struct coresight_device *csdev)
> * if we found a matching csdev then update the ECT
> * association pointer for the device with this CTI.
> */
> - coresight_set_assoc_ectdev_mutex(csdev,
> - ect_item->csdev);
> + coresight_add_helper_mutex(csdev, ect_item->csdev);
> break;
> }
> }
> @@ -582,26 +584,30 @@ static void cti_add_assoc_to_csdev(struct coresight_device *csdev)
>
> /*
> * Removing the associated devices is easier.
> - * A CTI will not have a value for csdev->ect_dev.
> */
> static void cti_remove_assoc_from_csdev(struct coresight_device *csdev)
> {
> struct cti_drvdata *ctidrv;
> struct cti_trig_con *tc;
> + union coresight_dev_subtype cti_subtype = {
> + .helper_subtype = CORESIGHT_DEV_SUBTYPE_HELPER_ECT_CTI
> + };
> + struct coresight_device *cti_csdev = coresight_find_output_type(
> + csdev->pdata, CORESIGHT_DEV_TYPE_HELPER, cti_subtype);
minor nit: Please could we split the initialisation ? Or at least move
this after the next variable declaration below ?
Rest looks fine to me.
Suzuki
> struct cti_device *ctidev;
>
> + if (!cti_csdev)
> + return;
> +
> mutex_lock(&ect_mutex);
> - if (csdev->ect_dev) {
> - ctidrv = csdev_to_cti_drvdata(csdev->ect_dev);
> - ctidev = &ctidrv->ctidev;
> - list_for_each_entry(tc, &ctidev->trig_cons, node) {
> - if (tc->con_dev == csdev) {
> - cti_remove_sysfs_link(ctidrv, tc);
> - tc->con_dev = NULL;
> - break;
> - }
> + ctidrv = csdev_to_cti_drvdata(cti_csdev);
> + ctidev = &ctidrv->ctidev;
> + list_for_each_entry(tc, &ctidev->trig_cons, node) {
> + if (tc->con_dev == csdev) {
> + cti_remove_sysfs_link(ctidrv, tc);
> + tc->con_dev = NULL;
> + break;
> }
> - csdev->ect_dev = NULL;
> }
> mutex_unlock(&ect_mutex);
> }
> @@ -630,8 +636,8 @@ static void cti_update_conn_xrefs(struct cti_drvdata *drvdata)
> /* if we can set the sysfs link */
> if (cti_add_sysfs_link(drvdata, tc))
> /* set the CTI/csdev association */
> - coresight_set_assoc_ectdev_mutex(tc->con_dev,
> - drvdata->csdev);
> + coresight_add_helper_mutex(tc->con_dev,
> + drvdata->csdev);
> else
> /* otherwise remove reference from CTI */
> tc->con_dev = NULL;
> @@ -646,8 +652,6 @@ static void cti_remove_conn_xrefs(struct cti_drvdata *drvdata)
>
> list_for_each_entry(tc, &ctidev->trig_cons, node) {
> if (tc->con_dev) {
> - coresight_set_assoc_ectdev_mutex(tc->con_dev,
> - NULL);
> cti_remove_sysfs_link(drvdata, tc);
> tc->con_dev = NULL;
> }
> @@ -795,27 +799,27 @@ static void cti_pm_release(struct cti_drvdata *drvdata)
> }
>
> /** cti ect operations **/
> -int cti_enable(struct coresight_device *csdev)
> +int cti_enable(struct coresight_device *csdev, enum cs_mode mode, void *data)
> {
> struct cti_drvdata *drvdata = csdev_to_cti_drvdata(csdev);
>
> return cti_enable_hw(drvdata);
> }
>
> -int cti_disable(struct coresight_device *csdev)
> +int cti_disable(struct coresight_device *csdev, void *data)
> {
> struct cti_drvdata *drvdata = csdev_to_cti_drvdata(csdev);
>
> return cti_disable_hw(drvdata);
> }
>
> -static const struct coresight_ops_ect cti_ops_ect = {
> +static const struct coresight_ops_helper cti_ops_ect = {
> .enable = cti_enable,
> .disable = cti_disable,
> };
>
> static const struct coresight_ops cti_ops = {
> - .ect_ops = &cti_ops_ect,
> + .helper_ops = &cti_ops_ect,
> };
>
> /*
> @@ -922,8 +926,8 @@ static int cti_probe(struct amba_device *adev, const struct amba_id *id)
>
> /* set up coresight component description */
> cti_desc.pdata = pdata;
> - cti_desc.type = CORESIGHT_DEV_TYPE_ECT;
> - cti_desc.subtype.ect_subtype = CORESIGHT_DEV_SUBTYPE_ECT_CTI;
> + cti_desc.type = CORESIGHT_DEV_TYPE_HELPER;
> + cti_desc.subtype.helper_subtype = CORESIGHT_DEV_SUBTYPE_HELPER_ECT_CTI;
> cti_desc.ops = &cti_ops;
> cti_desc.groups = drvdata->ctidev.con_groups;
> cti_desc.dev = dev;
> diff --git a/drivers/hwtracing/coresight/coresight-cti-sysfs.c b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
> index e528cff9d4e2..d25dd2737b49 100644
> --- a/drivers/hwtracing/coresight/coresight-cti-sysfs.c
> +++ b/drivers/hwtracing/coresight/coresight-cti-sysfs.c
> @@ -112,11 +112,11 @@ static ssize_t enable_store(struct device *dev,
> ret = pm_runtime_resume_and_get(dev->parent);
> if (ret)
> return ret;
> - ret = cti_enable(drvdata->csdev);
> + ret = cti_enable(drvdata->csdev, CS_MODE_SYSFS, NULL);
> if (ret)
> pm_runtime_put(dev->parent);
> } else {
> - ret = cti_disable(drvdata->csdev);
> + ret = cti_disable(drvdata->csdev, NULL);
> if (!ret)
> pm_runtime_put(dev->parent);
> }
> diff --git a/drivers/hwtracing/coresight/coresight-cti.h b/drivers/hwtracing/coresight/coresight-cti.h
> index 8b106b13a244..cb9ee616d01f 100644
> --- a/drivers/hwtracing/coresight/coresight-cti.h
> +++ b/drivers/hwtracing/coresight/coresight-cti.h
> @@ -215,8 +215,8 @@ int cti_add_connection_entry(struct device *dev, struct cti_drvdata *drvdata,
> const char *assoc_dev_name);
> struct cti_trig_con *cti_allocate_trig_con(struct device *dev, int in_sigs,
> int out_sigs);
> -int cti_enable(struct coresight_device *csdev);
> -int cti_disable(struct coresight_device *csdev);
> +int cti_enable(struct coresight_device *csdev, enum cs_mode mode, void *data);
> +int cti_disable(struct coresight_device *csdev, void *data);
> void cti_write_all_hw_regs(struct cti_drvdata *drvdata);
> void cti_write_intack(struct device *dev, u32 ackval);
> void cti_write_single_reg(struct cti_drvdata *drvdata, int offset, u32 value);
> diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
> index a843f9d5c737..fff565d1cb42 100644
> --- a/drivers/hwtracing/coresight/coresight-priv.h
> +++ b/drivers/hwtracing/coresight/coresight-priv.h
> @@ -211,8 +211,8 @@ void coresight_release_platform_data(struct coresight_device *csdev,
> struct coresight_platform_data *pdata);
> struct coresight_device *
> coresight_find_csdev_by_fwnode(struct fwnode_handle *r_fwnode);
> -void coresight_set_assoc_ectdev_mutex(struct coresight_device *csdev,
> - struct coresight_device *ect_csdev);
> +void coresight_add_helper_mutex(struct coresight_device *csdev,
> + struct coresight_device *helper);
>
> void coresight_set_percpu_sink(int cpu, struct coresight_device *csdev);
> struct coresight_device *coresight_get_percpu_sink(int cpu);
> diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c
> index 464ba5e1343b..dd78e9fcfc4d 100644
> --- a/drivers/hwtracing/coresight/coresight-sysfs.c
> +++ b/drivers/hwtracing/coresight/coresight-sysfs.c
> @@ -148,6 +148,10 @@ int coresight_make_links(struct coresight_device *orig,
> char *outs = NULL, *ins = NULL;
> struct coresight_sysfs_link *link = NULL;
>
> + /* Helper devices aren't shown in sysfs */
> + if (conn->dest_port == -1 && conn->src_port == -1)
> + return 0;
> +
> do {
> outs = devm_kasprintf(&orig->dev, GFP_KERNEL,
> "out:%d", conn->src_port);
> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> index d2739a0286f1..ed37552761e4 100644
> --- a/include/linux/coresight.h
> +++ b/include/linux/coresight.h
> @@ -40,8 +40,7 @@ enum coresight_dev_type {
> CORESIGHT_DEV_TYPE_LINK,
> CORESIGHT_DEV_TYPE_LINKSINK,
> CORESIGHT_DEV_TYPE_SOURCE,
> - CORESIGHT_DEV_TYPE_HELPER,
> - CORESIGHT_DEV_TYPE_ECT,
> + CORESIGHT_DEV_TYPE_HELPER
> };
>
> enum coresight_dev_subtype_sink {
> @@ -66,12 +65,7 @@ enum coresight_dev_subtype_source {
>
> enum coresight_dev_subtype_helper {
> CORESIGHT_DEV_SUBTYPE_HELPER_CATU,
> -};
> -
> -/* Embedded Cross Trigger (ECT) sub-types */
> -enum coresight_dev_subtype_ect {
> - CORESIGHT_DEV_SUBTYPE_ECT_NONE,
> - CORESIGHT_DEV_SUBTYPE_ECT_CTI,
> + CORESIGHT_DEV_SUBTYPE_HELPER_ECT_CTI
> };
>
> /**
> @@ -84,8 +78,6 @@ enum coresight_dev_subtype_ect {
> * by @coresight_dev_subtype_source.
> * @helper_subtype: type of helper this component is, as defined
> * by @coresight_dev_subtype_helper.
> - * @ect_subtype: type of cross trigger this component is, as
> - * defined by @coresight_dev_subtype_ect
> */
> union coresight_dev_subtype {
> /* We have some devices which acts as LINK and SINK */
> @@ -95,7 +87,6 @@ union coresight_dev_subtype {
> };
> enum coresight_dev_subtype_source source_subtype;
> enum coresight_dev_subtype_helper helper_subtype;
> - enum coresight_dev_subtype_ect ect_subtype;
> };
>
> /**
> @@ -237,8 +228,6 @@ struct coresight_sysfs_link {
> * from source to that sink.
> * @ea: Device attribute for sink representation under PMU directory.
> * @def_sink: cached reference to default sink found for this device.
> - * @ect_dev: Associated cross trigger device. Not part of the trace data
> - * path or connections.
> * @nr_links: number of sysfs links created to other components from this
> * device. These will appear in the "connections" group.
> * @has_conns_grp: Have added a "connections" group for sysfs links.
> @@ -261,12 +250,9 @@ struct coresight_device {
> bool activated; /* true only if a sink is part of a path */
> struct dev_ext_attribute *ea;
> struct coresight_device *def_sink;
> - /* cross trigger handling */
> - struct coresight_device *ect_dev;
> /* sysfs links between components */
> int nr_links;
> bool has_conns_grp;
> - bool ect_enabled; /* true only if associated ect device is enabled */
> /* system configuration and feature lists */
> struct list_head feature_csdev_list;
> struct list_head config_csdev_list;
> @@ -378,23 +364,11 @@ struct coresight_ops_helper {
> int (*disable)(struct coresight_device *csdev, void *data);
> };
>
> -/**
> - * struct coresight_ops_ect - Ops for an embedded cross trigger device
> - *
> - * @enable : Enable the device
> - * @disable : Disable the device
> - */
> -struct coresight_ops_ect {
> - int (*enable)(struct coresight_device *csdev);
> - int (*disable)(struct coresight_device *csdev);
> -};
> -
> struct coresight_ops {
> const struct coresight_ops_sink *sink_ops;
> const struct coresight_ops_link *link_ops;
> const struct coresight_ops_source *source_ops;
> const struct coresight_ops_helper *helper_ops;
> - const struct coresight_ops_ect *ect_ops;
> };
>
> #if IS_ENABLED(CONFIG_CORESIGHT)
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