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    SubjectRe: [PATCH v2 9/9] coresight: Fix CTI module refcount leak by making it a helper device
    Hi James

    On Fri, 10 Mar 2023 at 16:07, James Clark <james.clark@arm.com> 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@arm.com>
    > ---
    > 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

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