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2848 discussions

Re: [PATCH] coresight: syscfg: fix deadlock on device registration failure

by Leo Yan

On Wed, Sep 09, 2026 at 09:34:07AM +0800, yingchao deng wrote: [...] > I'll send v2 with your suggested change. Thanks a lot!

1 week, 1 day

Re: [PATCH] coresight: Fix clock refcount imbalance on platform probe failure

by Leo Yan

Hi Jie, Thanks for fixing! It is shame that my single patch caused issues both in driver's probe and remove - I have to admit that I don't understand runtime PM's state machine. TBC, this patch only fixes probe. The driver's remove is fixed in: https://lore.kernel.org/linux-arm-kernel/20260710-fix-clock-refcount-unbala… The series above and this patch should be picked up together so can have complete fix. > The probe wrapper then unconditionally calls pm_runtime_put() > regardless of whether the inner probe succeeded, so on failure this > also fires runtime_suspend() and disables the same clocks a first > time. pm_runtime_put() can be used for success case, but for the failure case, we should disable the runtime PM but not release reference: https://docs.kernel.org/power/runtime_pm.html#runtime-pm-initialization-dev… > @@ -632,11 +632,14 @@ static int catu_platform_probe(struct platform_device *pdev) > pm_runtime_enable(&pdev->dev); > > ret = __catu_probe(&pdev->dev, res); > - pm_runtime_put(&pdev->dev); > - if (ret) > + if (ret) { > + pm_runtime_put_noidle(&pdev->dev); > pm_runtime_disable(&pdev->dev); Nitpick: please reverse the sequence between pm_runtime_put_noidle() and pm_runtime_disable(). As we need to first disable runtime PM for the device, then release usage reference. Since the driver core will reset device's active state, AI told me that calling pm_runtime_set_suspended() is redundant. It is still good to explicitly call it for bookkeeping. This can be aligned with the change in driver remove. Thus, please update the flow: pm_runtime_disable(&pdev->dev); pm_runtime_set_suspended(dev); pm_runtime_put_noidle(&pdev->dev); With the update: Reviewed-by: Leo Yan <leo.yan(a)arm.com>

1 week, 1 day

Re: [PATCH] coresight: tpdm: initialize spinlock before exposing sysfs

by Leo Yan

On Tue, Aug 25, 2026 at 10:06:47AM +0800, yingchao wrote: > From: Yingchao Deng <dengyingchao(a)kylinsec.com.cn> > > tpdm_probe() initializes drvdata->spinlock after coresight_register(), but > the sysfs attributes registered by coresight_register() use the spinlock. > This exposes a window where a concurrent sysfs write can lock an > uninitialized spinlock. > > Initialize the spinlock before coresight_register(). > > Fixes: b3c71626a933 ("Coresight: Add coresight TPDM source driver") > Signed-off-by: Yingchao Deng <dengyingchao(a)kylinsec.com.cn> Reviewed-by: Leo Yan <leo.yan(a)arm.com>

1 week, 2 days

Re: [PATCH] coresight: syscfg: fix deadlock on device registration failure

by Leo Yan

On Tue, Aug 25, 2026 at 09:47:17AM +0800, yingchao wrote: > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c > index 2bfdd7b45e49..d0e7e4720e46 100644 > --- a/drivers/hwtracing/coresight/coresight-syscfg.c > +++ b/drivers/hwtracing/coresight/coresight-syscfg.c > @@ -1210,8 +1210,14 @@ static int cscfg_create_device(void) > dev->init_name = "cs_system_cfg"; > > err = device_register(dev); > - if (err) > + if (err) { > + /* put_device() triggers cscfg_dev_release() which takes > + * cscfg_mutex, so drop the lock first to avoid deadlocking. > + */ > + mutex_unlock(&cscfg_mutex); > put_device(dev); > + return err; > + } As module init and exit are serialized by the kernel, I don't think we need the mutex to protect the allocation and freeing of cscfg_mgr. The mutex should only be used for exclusively access cscfg_mgr. So how about the change below? ---8<--- diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c index 2bfdd7b45e49..2dd0b29f44e4 100644 --- a/drivers/hwtracing/coresight/coresight-syscfg.c +++ b/drivers/hwtracing/coresight/coresight-syscfg.c @@ -1173,27 +1173,21 @@ struct device *cscfg_device(void) /* Must have a release function or the kernel will complain on module unload */ static void cscfg_dev_release(struct device *dev) { - mutex_lock(&cscfg_mutex); kfree(cscfg_mgr); cscfg_mgr = NULL; - mutex_unlock(&cscfg_mutex); } /* a device is needed to "own" some kernel elements such as sysfs entries. */ static int cscfg_create_device(void) { struct device *dev; - int err = -ENOMEM; - - mutex_lock(&cscfg_mutex); - if (cscfg_mgr) { - err = -EINVAL; - goto create_dev_exit_unlock; - } + int err; cscfg_mgr = kzalloc_obj(struct cscfg_manager); if (!cscfg_mgr) - goto create_dev_exit_unlock; + return -ENOMEM; + + mutex_lock(&cscfg_mutex); /* initialise the cscfg_mgr structure */ INIT_LIST_HEAD(&cscfg_mgr->csdev_desc_list); @@ -1204,6 +1198,8 @@ static int cscfg_create_device(void) cscfg_mgr->load_state = CSCFG_NONE; raw_spin_lock_init(&cscfg_mgr->sysfs_store_lock); + mutex_unlock(&cscfg_mutex); + /* setup the device */ dev = cscfg_device(); dev->release = cscfg_dev_release; @@ -1213,8 +1209,6 @@ static int cscfg_create_device(void) if (err) put_device(dev); -create_dev_exit_unlock: - mutex_unlock(&cscfg_mutex); return err; }

1 week, 2 days

[PATCH 0/6] perf: cs-etm: HW_ID improvements

by James Clark

The driver might not always be able to write HW_IDs, but we don't need them for unformatted mode anyway, so fix that in commit ("perf cs-etm: Synthesize missing HW_ID mappings for raw trace"). At the same time, give the driver another chance to send them in commit ("coresight: perf: Retry failed HW_ID writes"). The other commits are semi-related improvements and fixes. ("perf: cs-etm: Respect --no-itrace option") makes debugging broken Coresight perf.data files easier. Applies on top of "[PATCH v2 00/14] perf cs-etm: Per-thread mode fixes and snapshot wrap support" Signed-off-by: James Clark <james.clark(a)linaro.org> --- James Clark (5): perf: cs-etm: Don't add global v0 HW_IDs to unformatted queues perf cs-etm: Free partially created queues perf: cs-etm: Respect --no-itrace option perf/core: Return errors from perf_report_aux_output_id() coresight: perf: Retry failed HW_ID writes Leo Yan (1): perf cs-etm: Synthesize missing HW_ID mappings for raw trace drivers/hwtracing/coresight/coresight-etm-perf.c | 52 +++++---- include/linux/perf_event.h | 2 +- kernel/events/core.c | 6 +- tools/perf/util/auxtrace.c | 2 +- tools/perf/util/auxtrace.h | 1 + tools/perf/util/cs-etm.c | 143 ++++++++++++++++------- 6 files changed, 139 insertions(+), 67 deletions(-) --- base-commit: 78148c85297024ffe7a709acb7cc4fc907271176 change-id: 20260706-james-cs-hw_id-output-failure-1d06d042ef96 prerequisite-change-id: 20260605-james-cs-unformatted-per-thread-fix-50e723aa7f0e:v2 prerequisite-patch-id: 1aa32269a3a7dc76840dd8a24cb5a8715507e898 prerequisite-patch-id: ef471f468351462f67efa58a09a3461306ac5a0a prerequisite-patch-id: c78946cf4ec1c7722570865403a3562625bdaa33 prerequisite-patch-id: 0b953eee0252db3c7ba3ef1e3397048a94482ca2 prerequisite-patch-id: 27da72c2f01bcc68205bbcc14d5019369c02cb83 prerequisite-patch-id: 365c6d5f71c754e4c690b5ebed3453565bb5b809 prerequisite-patch-id: 64e9419a41082a2db3daf255baf0fb40efbae5dd prerequisite-patch-id: 1dc2e6ef8e76b369736b4c88560302861b2e4faf prerequisite-patch-id: b7de38ec4d90f5b45d56390a4e5919a1d6439951 prerequisite-patch-id: 3548d5b161cfb8c11a166ca2b3228ca4821f1ca0 prerequisite-patch-id: 97e66600218a2b32e5b21d0abcb6321590f98de9 prerequisite-patch-id: 292282b20bd8ad7d096ee7ffbc55dcfb75455f53 prerequisite-patch-id: c80259b47850ba65c985c85a29c8cf4948463d59 Best regards, -- James Clark <james.clark(a)linaro.org>

1 week, 6 days

Re: [PATCH] coresight: fix typos in comments

by Leo Yan

On Fri, Sep 04, 2026 at 04:40:51PM +0530, Hemanth Selam wrote: > Fix typos in comments, reported by scripts/checkpatch.pl using the > misspelling list in scripts/spelling.txt. Only touches comments, no code > changes. > > Assisted-by: Cursor:claude-opus-5 > Signed-off-by: Hemanth Selam <hemanth.selam(a)gmail.com> Reviewed-by: Leo Yan <leo.yan(a)arm.com>

1 week, 6 days

Re: [PATCH] docs: fix typos in Documentation/ABI/testing/sysfs-bus-coresight-devices-etm3x

by Leo Yan

On Fri, Sep 04, 2026 at 09:49:42AM +0530, tspamiitesh(a)gmail.com wrote: [...] > -Description: (RW) Enable/disable tracing on this specific trace entiry. > +Description: (RW) Enable/disable tracing on this specific trace entry. > Enabling a source implies the source has been configured > - properly and a sink has been identidifed for it. The path > + properly and a sink has been indentified for it. The path s/indentified/identified ?

1 week, 6 days

Re: [PATCH v2] coresight: tnoc: fix trace ID path assignment failure on non-AMBA tnoc

by Leo Yan

On Wed, Sep 02, 2026 at 05:41:43PM +0800, Jie Gan wrote: > For a tnoc device not on the AMBA bus, atid was set to -EOPNOTSUPP. > trace_noc_id() returns this value directly to > coresight_path_assign_trace_id(), which only treats a literal 0 > return as "this device has no ID, keep searching the path" - > any other value is checked against IS_VALID_CS_TRACE_ID() and > rejected. A negative atid therefore made path assignment fail with > -EINVAL instead of falling through to the next device in the path > that could supply a valid trace ID. > > Use 0, the same sentinel coresight_path_assign_trace_id() already > recognizes as "not allocated", instead of -EOPNOTSUPP. > > Fixes: 5799dee92dc2 ("coresight-tnoc: add platform driver to support Interconnect TNOC") > Signed-off-by: Jie Gan <jie.gan(a)oss.qualcomm.com> Reviewed-by: Leo Yan <leo.yan(a)arm.com>

2 weeks, 1 day

Re: [PATCH] coresight: fix trace ID search skipping pass-through NoC devices

by Leo Yan

On Wed, Sep 02, 2026 at 04:35:11PM +0800, Jie Gan wrote: [...] > Hi Leo, > > Thanks for the suggestion. You're welcome! > I will fix this in the TNOC driver. I agree that there is no need to use > additional error codes to report the failure. > > I will post the new fix patch after below patch[1] to be applied to avoid > conflict. The patch in the link has no fix tag, but current patch is a simple fix. I'd suggest to give priority this patch - this is friendly for porting to stable kernels. If there have dependency (based on your local test), you could explictly mention the dependency in cover letter and resend the tnoc probe series. Thanks, Leo > [1] https://lore.kernel.org/all/20260710-fix-tracenoc-probe-issue-v6-2-41eb36fe…

2 weeks, 1 day

Re: [PATCH] coresight: fix trace ID search skipping pass-through NoC devices

by Leo Yan

Hi Jie, On Mon, Aug 17, 2026 at 04:50:15PM +0800, Jie Gan wrote: [...] > @@ -953,8 +953,12 @@ int coresight_path_assign_trace_id(struct coresight_path *path, > /* Assign a trace ID to the path for the first device that wants to do it */ > trace_id = coresight_get_trace_id(nd->csdev, mode, sink); > > - /* 0 means the device has no ID assignment, so keep searching */ > - if (trace_id == 0) > + /* > + * 0 means the device has no ID assignment, and -EOPNOTSUPP > + * means the device explicitly declines to assign one (e.g. a > + * pass-through NoC) - in both cases keep searching downstream. > + */ > + if (trace_id == 0 || trace_id == -EOPNOTSUPP) > continue; Based on IS_VALID_CS_TRACE_ID(), I see 0 is for no ID assignment, could you improve a bit tnoc.c instead? If so, We don't need to add a new error for the same purpose. ---8<--- diff --git a/drivers/hwtracing/coresight/coresight-tnoc.c b/drivers/hwtracing/coresight/coresight-tnoc.c index 9e8de4323d28..bf221c1e5c48 100644 --- a/drivers/hwtracing/coresight/coresight-tnoc.c +++ b/drivers/hwtracing/coresight/coresight-tnoc.c @@ -51,8 +51,8 @@ static void trace_noc_enable_hw(struct trace_noc_drvdata *drvdata) { u32 val; - /* No valid ATID, simply enable the unit */ - if (drvdata->atid == -EOPNOTSUPP) { + /* 0 means no ID assignment, simply enable the unit */ + if (!drvdata->atid) { writel(TRACE_NOC_CTRL_PORTEN, drvdata->base + TRACE_NOC_CTRL); return; } @@ -130,10 +130,8 @@ static int trace_noc_init_default_data(struct trace_noc_drvdata *drvdata) { int atid; - if (!dev_is_amba(drvdata->dev)) { - drvdata->atid = -EOPNOTSUPP; + if (!dev_is_amba(drvdata->dev)) return 0; - } atid = coresight_trace_id_get_system_id(); if (atid < 0)

2 weeks, 1 day

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