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coresight: Fix CTI module refcount leak by making it a helper device
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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>
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@James-A-Clark @intel-lab-lkp
James-A-Clark authored and intel-lab-lkp committed Mar 8, 2023
1 parent 810f343 commit f9e9285
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Showing 5 changed files with 53 additions and 112 deletions.
73 changes: 10 additions & 63 deletions drivers/hwtracing/coresight/coresight-core.c
View file
Expand Up @@ -253,57 +253,21 @@ 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.
*/
void coresight_set_assoc_ectdev_mutex(struct coresight_device *csdev,
struct coresight_device *ect_csdev)
{
struct coresight_connection conn = {};

mutex_lock(&coresight_mutex);
csdev->ect_dev = ect_csdev;
conn.child_fwnode = fwnode_handle_get(dev_fwnode(&ect_csdev->dev));
conn.child_dev = ect_csdev;
conn.child_port = conn.outport = -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);
Expand All @@ -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;
Expand All @@ -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;
}

Expand All @@ -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;
}

Expand Down Expand Up @@ -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++)
Expand All @@ -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;
}
}
Expand Down Expand Up @@ -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;
Expand Down
56 changes: 37 additions & 19 deletions drivers/hwtracing/coresight/coresight-cti-core.c
View file
Expand Up @@ -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 */
Expand All @@ -580,6 +583,22 @@ static void cti_add_assoc_to_csdev(struct coresight_device *csdev)
mutex_unlock(&ect_mutex);
}

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].child_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.
Expand All @@ -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);
}
Expand Down Expand Up @@ -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;
}
Expand Down Expand Up @@ -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,
};

/*
Expand Down Expand Up @@ -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;
Expand Down
4 changes: 2 additions & 2 deletions drivers/hwtracing/coresight/coresight-cti-sysfs.c
View file
Expand Up @@ -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);
}
Expand Down
4 changes: 2 additions & 2 deletions drivers/hwtracing/coresight/coresight-cti.h
View file
Expand Up @@ -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);
Expand Down
28 changes: 2 additions & 26 deletions include/linux/coresight.h
View file
Expand Up @@ -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 {
Expand All @@ -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
};

/**
Expand All @@ -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 */
Expand All @@ -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;
};

/**
Expand Down Expand Up @@ -261,12 +252,9 @@ 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;
Expand Down Expand Up @@ -374,23 +362,11 @@ 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)
Expand Down

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