Re: [PATCH v3 13/13] coresight: Fix CTI module refcount leak by making it a helper device
From: Suzuki K Poulose
Date: Tue Apr 04 2023 - 05:21:37 EST
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@xxxxxxx>
---
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)