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    Subject[PATCH v3 13/13] coresight: Fix CTI module refcount leak by making it a helper device
    Date
    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 | 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)
    {
    + 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.
    + */
    + 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);
    + 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);
    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)
    --
    2.34.1
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