Messages in this thread | | | Date | Tue, 4 Apr 2023 13:55:22 +0100 | Subject | Re: [PATCH v3 13/13] coresight: Fix CTI module refcount leak by making it a helper device | From | James Clark <> |
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On 04/04/2023 10:21, Suzuki K Poulose wrote: > 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@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) > > 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 : > There is already a bit of a comment in the description but I can expand on it more.
> might_sleep() and lockdep_assert_not_held(&coresight_mutex); > > in the function. >
I'm not sure if lockdep_assert_not_held() would be right because sometimes it could be held if another device is being created at the same time? Or something like a session is started at the same time a CTI device is added.
>> { >> + 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); >
Yeah I thought about doing that too, will change it.
>> + 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) >
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