Re: [PATCH v2 9/9] coresight: Fix CTI module refcount leak by making it a helper device
From: Mike Leach
Date: Wed Mar 22 2023 - 05:30:13 EST
Hi James
On Fri, 10 Mar 2023 at 16:07, James Clark <james.clark@xxxxxxx> 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@xxxxxxx>
> ---
> drivers/hwtracing/coresight/coresight-core.c | 73 +++----------------
> .../hwtracing/coresight/coresight-cti-core.c | 56 +++++++++-----
> .../hwtracing/coresight/coresight-cti-sysfs.c | 4 +-
> drivers/hwtracing/coresight/coresight-cti.h | 4 +-
> include/linux/coresight.h | 28 +------
> 5 files changed, 53 insertions(+), 112 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> index 3e6ccd9e8d4e..94d84404fb29 100644
> --- a/drivers/hwtracing/coresight/coresight-core.c
> +++ b/drivers/hwtracing/coresight/coresight-core.c
> @@ -253,48 +253,6 @@ 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
> * to avoid a race with coresight_enable that may try to use this value.
> @@ -302,8 +260,14 @@ coresight_control_assoc_ectdev(struct coresight_device *csdev, bool enable)
> void coresight_set_assoc_ectdev_mutex(struct coresight_device *csdev,
> struct coresight_device *ect_csdev)
Now we have generic helpers this could become a generic "add helper"
routine - for helpers such as CTI that aren't picked up by the trace
data port graph that catches other things.
e.g.
coresight_set_assoc_helper_mutex(struct coresight_device *csdev,
struct coresight_device *helper_csdev)
Regards
Mike
> {
> + struct coresight_connection conn = {};
> +
> mutex_lock(&coresight_mutex);
> - csdev->ect_dev = ect_csdev;
> + conn.remote_fwnode = fwnode_handle_get(dev_fwnode(&ect_csdev->dev));
> + conn.remote_dev = ect_csdev;
> + conn.remote_port = conn.port = -1;
> + coresight_add_conn(csdev->dev.parent, csdev->pdata, &conn);
> + coresight_fixup_inputs(csdev);
> mutex_unlock(&coresight_mutex);
> }
> EXPORT_SYMBOL_GPL(coresight_set_assoc_ectdev_mutex);
> @@ -320,12 +284,8 @@ 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;
> @@ -343,7 +303,6 @@ 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;
> }
>
> @@ -368,17 +327,11 @@ static int coresight_enable_link(struct coresight_device *csdev,
> return outport;
>
> if (link_ops(csdev)->enable) {
> - ret = coresight_control_assoc_ectdev(csdev, true);
> - if (!ret) {
> - ret = link_ops(csdev)->enable(csdev, inport, outport);
> - if (ret)
> - coresight_control_assoc_ectdev(csdev, false);
> - }
> + ret = link_ops(csdev)->enable(csdev, inport, outport);
> + if (!ret)
> + csdev->enable = true;
> }
>
> - if (!ret)
> - csdev->enable = true;
> -
> return ret;
> }
>
> @@ -407,7 +360,6 @@ static void coresight_disable_link(struct coresight_device *csdev,
>
> if (link_ops(csdev)->disable) {
> link_ops(csdev)->disable(csdev, inport, outport);
> - coresight_control_assoc_ectdev(csdev, false);
> }
>
> for (i = 0; i < nr_conns; i++)
> @@ -424,12 +376,8 @@ static int coresight_enable_source(struct coresight_device *csdev,
>
> 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, NULL, mode);
> if (ret) {
> - coresight_control_assoc_ectdev(csdev, false);
> return ret;
> }
> }
> @@ -482,7 +430,6 @@ static bool coresight_disable_source(struct coresight_device *csdev)
> if (atomic_dec_return(csdev->refcnt) == 0) {
> if (source_ops(csdev)->disable)
> source_ops(csdev)->disable(csdev, NULL);
> - coresight_control_assoc_ectdev(csdev, false);
> csdev->enable = false;
> }
> return !csdev->enable;
> diff --git a/drivers/hwtracing/coresight/coresight-cti-core.c b/drivers/hwtracing/coresight/coresight-cti-core.c
> index 277c890a1f1f..dbce6680759f 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 */
> @@ -580,6 +583,22 @@ static void cti_add_assoc_to_csdev(struct coresight_device *csdev)
> mutex_unlock(&ect_mutex);
> }
>
> +static struct coresight_device *cti__get_cti_device(struct coresight_device *csdev)
> +{
> + int i;
> + struct coresight_device *tmp;
> +
> + for (i = 0; i < csdev->pdata->nr_outconns; i++) {
> + tmp = csdev->pdata->out_conns[i].remote_dev;
> +
> + if (tmp && tmp->type == CORESIGHT_DEV_TYPE_HELPER &&
> + tmp->subtype.helper_subtype ==
> + CORESIGHT_DEV_SUBTYPE_HELPER_ECT_CTI)
> + return tmp;
> + }
> + return NULL;
> +}
> +
> /*
> * Removing the associated devices is easier.
> * A CTI will not have a value for csdev->ect_dev.
> @@ -588,20 +607,21 @@ static void cti_remove_assoc_from_csdev(struct coresight_device *csdev)
> {
> struct cti_drvdata *ctidrv;
> struct cti_trig_con *tc;
> + struct coresight_device *cti_csdev = cti__get_cti_device(csdev);
> 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);
> }
> @@ -646,8 +666,6 @@ 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 +813,27 @@ 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 +940,8 @@ 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/include/linux/coresight.h b/include/linux/coresight.h
> index c6ee1634d813..cf7a8658ee88 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;
> };
>
> /**
> @@ -264,12 +255,9 @@ 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;
> @@ -377,23 +365,11 @@ 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)
> --
> 2.34.1
>
--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK