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

On 10/03/2023 16:06, 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@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) {

• 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);

Can this cause duplicate entries to be created for the other "existing" output connections of csdev ? IIUC, we just need to create the input connection for the connection we are creating now and not all of the out_conns. They should have been populated at coresight_register(). Now you may not hit this, because we don't have any actual "defined" connections in the DT. But we need to be safe here.

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; }

super minor nit: You could remove the { } too

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);
  

  }

super minor nit: You may remove the { } s.

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) ||
  

Should we add a helper to check this : is_coresight_ctidev(csdev) ?

•    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)

minor nit: no perf tool naming style please ;-)

+{

• 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)
  

As mentioned above, a helper to check this would benefit reading.

• 	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 */

nit: Update comments above the struct too ?

Thanks Suzuki

/* 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)