Message-Id: <20230310160610.742382-10-james.clark@arm.com>
Date:   Fri, 10 Mar 2023 16:06:08 +0000
From:   James Clark <james.clark@....com>
To:     coresight@...ts.linaro.org
Cc:     James Clark <james.clark@....com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 9/9] coresight: Fix CTI module refcount leak by making it a helper device

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@....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)
 {
+	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

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