Re: [PATCH v11 3/9] coresight: etm4x: fix inconsistencies with sysfs configuration

[Yeoreum Yun]

On Fri, Sep 18, 2026 at 02:49:09PM +0100, Mike Leach wrote:
> Hi,
> 
> On 9/15/26 12:34, Yeoreum Yun wrote:
> > The current ETM4x configuration via sysfs can lead to
> > several inconsistencies:
> > 
> >    - If the configuration is modified via sysfs while a perf session is
> >      active, the running configuration may differ before a sched-out and
> >      after a subsequent sched-in.
> > 
> >    - If a perf session and a sysfs session enable tracing concurrently,
> >      the configuration from configfs may become corrupted.
> > 
> >    - There is a risk of corrupting drvdata->config if a perf session enables
> >      tracing while cscfg_csdev_disable_active_config() is being handled in
> >      etm4_disable_sysfs().
> > 
> > To resolve these issues, separate the configuration into:
> > 
> >    - active_config: the configuration applied to the current session
> >    - config: the configuration set via sysfs
> > 
> 
> I'll add a comment about naming here - active_config is a bit overloaded in
> the code as it is also used by the csconfig code to represent a loaded and
> active configuration - which may at some point be applied to the
> active_config above.
> 
> If active_config is for the current session then curr_config would work.
> 
> Additionally config also appears as a local pointer in many of the
> functions. If this is the sysfs config then sysfs_config would work better.
> 
> This should make all the code a lot more readable, and easier to spot
> exactly which config we are dealing with.

Okay. then I'll change the each name with curr_config and sysfs_config
and rename all.

Thanks ;)

> 
> 
> > Additionally:
> > 
> >    - Apply the configuration from configfs after taking the appropriate mode.
> > 
> >    - Since active_config and related fields are accessed only by the local CPU
> >      in etm4_enable/disable_sysfs_smp_call() (similar to perf enable/disable),
> >      remove the lock/unlock from the sysfs enable/disable path and
> >      startup/dying_cpu except when to access config fields.
> > 
> > As the active_config is used for cfg-configfs, etmv4 doesn't need to set
> > its lock for the cfg-configfs since the active_config is proceted by cs_mode
> > otherwise it would make a possible cpu-stall when it get interrupt while
> > setting the sysfs configuration.
> > 
> > Therefore, set the drv_spinlock for cfg-configfs as NULL and
> > let the cfg-configfs disable irq without grap drv_spinlock when it is NULL.
> > 
> > Fixes: 54ff892b76c6 ("coresight: etm4x: splitting struct etmv4_drvdata")
> > Signed-off-by: Yeoreum Yun <yeoreum.yun@xxxxxxx>
> > ---
> >   drivers/hwtracing/coresight/coresight-config.c     |  18 ++--
> >   drivers/hwtracing/coresight/coresight-config.h     |  22 ++++
> >   drivers/hwtracing/coresight/coresight-etm4x-cfg.c  |  13 ++-
> >   drivers/hwtracing/coresight/coresight-etm4x-core.c | 118 ++++++++++++---------
> >   .../hwtracing/coresight/coresight-etm4x-sysfs.c    |   6 +-
> >   drivers/hwtracing/coresight/coresight-etm4x.h      |   4 +-
> >   6 files changed, 113 insertions(+), 68 deletions(-)
> > 
> > diff --git a/drivers/hwtracing/coresight/coresight-config.c b/drivers/hwtracing/coresight/coresight-config.c
> > index 4f72ae71b696e..0e296289f286d 100644
> > --- a/drivers/hwtracing/coresight/coresight-config.c
> > +++ b/drivers/hwtracing/coresight/coresight-config.c
> > @@ -73,13 +73,12 @@ static void cscfg_init_reg_param(struct cscfg_feature_csdev *feat_csdev,
> >   /* set values into the driver locations referenced in cscfg_reg_csdev */
> >   static int cscfg_set_on_enable(struct cscfg_feature_csdev *feat_csdev)
> >   {
> > -	unsigned long flags;
> >   	int i;
> > -	raw_spin_lock_irqsave(feat_csdev->drv_spinlock, flags);
> > -	for (i = 0; i < feat_csdev->nr_regs; i++)
> > -		cscfg_set_reg(&feat_csdev->regs_csdev[i]);
> > -	raw_spin_unlock_irqrestore(feat_csdev->drv_spinlock, flags);
> > +	scoped_guard(feat_csdev_lock, feat_csdev) {
> > +		for (i = 0; i < feat_csdev->nr_regs; i++)
> > +			cscfg_set_reg(&feat_csdev->regs_csdev[i]);
> > +	}
> >   	dev_dbg(&feat_csdev->csdev->dev, "Feature %s: %s",
> >   		feat_csdev->feat_desc->name, "set on enable");
> >   	return 0;
> > @@ -88,13 +87,12 @@ static int cscfg_set_on_enable(struct cscfg_feature_csdev *feat_csdev)
> >   /* copy back values from the driver locations referenced in cscfg_reg_csdev */
> >   static void cscfg_save_on_disable(struct cscfg_feature_csdev *feat_csdev)
> >   {
> > -	unsigned long flags;
> >   	int i;
> > -	raw_spin_lock_irqsave(feat_csdev->drv_spinlock, flags);
> > -	for (i = 0; i < feat_csdev->nr_regs; i++)
> > -		cscfg_save_reg(&feat_csdev->regs_csdev[i]);
> > -	raw_spin_unlock_irqrestore(feat_csdev->drv_spinlock, flags);
> > +	scoped_guard(feat_csdev_lock, feat_csdev) {
> > +		for (i = 0; i < feat_csdev->nr_regs; i++)
> > +			cscfg_save_reg(&feat_csdev->regs_csdev[i]);
> > +	}
> >   	dev_dbg(&feat_csdev->csdev->dev, "Feature %s: %s",
> >   		feat_csdev->feat_desc->name, "save on disable");
> >   }
> > diff --git a/drivers/hwtracing/coresight/coresight-config.h b/drivers/hwtracing/coresight/coresight-config.h
> > index 90fd937d3bd83..ae6295e308131 100644
> > --- a/drivers/hwtracing/coresight/coresight-config.h
> > +++ b/drivers/hwtracing/coresight/coresight-config.h
> > @@ -7,6 +7,7 @@
> >   #ifndef _CORESIGHT_CORESIGHT_CONFIG_H
> >   #define _CORESIGHT_CORESIGHT_CONFIG_H
> > +#include <linux/cleanup.h>
> >   #include <linux/coresight.h>
> >   #include <linux/types.h>
> > @@ -259,4 +260,25 @@ void cscfg_csdev_disable_config(struct cscfg_config_csdev *config_csdev);
> >   /* reset a feature to default values */
> >   void cscfg_reset_feat(struct cscfg_feature_csdev *feat_csdev);
> > +#define feat_csdev_lock(feat_csdev, flags)				\
> > +	do {								\
> > +		raw_spinlock_t *__lock = feat_csdev->drv_spinlock;	\
> > +		typecheck(unsigned long, flags);			\
> > +		if (__lock)						\
> > +			raw_spin_lock_irqsave(__lock, flags);		\
> > +	} while (0)
> > +
> > +#define feat_csdev_unlock(feat_csdev, flags)				\
> > +	do {								\
> > +		raw_spinlock_t *__lock = feat_csdev->drv_spinlock;	\
> > +		typecheck(unsigned long, flags);			\
> > +		if (__lock)						\
> > +			raw_spin_unlock_irqrestore(__lock, flags);	\
> > +	} while (0)
> > +
> > +DEFINE_LOCK_GUARD_1(feat_csdev_lock, struct cscfg_feature_csdev,
> > +		    feat_csdev_lock(_T->lock, _T->flags),
> > +		    feat_csdev_unlock(_T->lock, _T->flags),
> > +		    unsigned long flags)
> > +
> >   #endif /* _CORESIGHT_CORESIGHT_CONFIG_H */
> > diff --git a/drivers/hwtracing/coresight/coresight-etm4x-cfg.c b/drivers/hwtracing/coresight/coresight-etm4x-cfg.c
> > index e1a59b4345052..d24f533c623d0 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm4x-cfg.c
> > +++ b/drivers/hwtracing/coresight/coresight-etm4x-cfg.c
> > @@ -47,7 +47,7 @@ static int etm4_cfg_map_reg_offset(struct etmv4_drvdata *drvdata,
> >   				   struct cscfg_regval_csdev *reg_csdev, u32 offset)
> >   {
> >   	int err = -EINVAL, idx;
> > -	struct etmv4_config *drvcfg = &drvdata->config;
> > +	struct etmv4_config *drvcfg = &drvdata->active_config;
> >   	u32 off_mask;
> >   	if (((offset >= TRCEVENTCTL0R) && (offset <= TRCVIPCSSCTLR)) ||
> > @@ -154,11 +154,14 @@ static int etm4_cfg_load_feature(struct coresight_device *csdev,
> >   	int i = 0, err = 0;
> >   	/*
> > -	 * essential we set the device spinlock - this is used in the generic
> > -	 * programming routines when copying values into the drvdata structures
> > -	 * via the pointers setup in etm4_cfg_map_reg_offset().
> > +	 * drvdata structure of etm4 for configfs is active_config and
> > +	 * this active_config is protected with csdev->mode by restricting
> > +	 * access to active_config after mode changed to PERF or SYSFS.
> > +	 *
> > +	 * Therefore, it doesn't need to protected with etmv4_drvdata->spinlock
> > +	 * to feature applying and set the NULL.
> >   	 */
> > -	feat_csdev->drv_spinlock = &drvdata->spinlock;
> > +	feat_csdev->drv_spinlock = NULL;
> >   	/* process the register descriptions */
> >   	for (i = 0; i < feat_csdev->nr_regs && !err; i++) {
> > diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > index 2247ad55d4442..2df7f592bb5cf 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > @@ -239,6 +239,7 @@ void etm4_release_trace_id(struct etmv4_drvdata *drvdata)
> >   struct etm4_enable_arg {
> >   	struct etmv4_drvdata *drvdata;
> >   	struct coresight_path *path;
> > +	struct etmv4_config config;
> 
> drvdata contains both active_config and config - why the extra copy here?

This is because of a minor consistency before applying the configuration
to hardware. Since drvdata->sysfs_config could be modified while copying
the contents into the active_config as a purpose of snapshot at the time
of enable, add this argument.

For example, while enabling, sysfs could modify the ctxid_mask0 and
ctxid_mask1 and this could be teared when active_config is copied from
drvdata->config directly.

Therefore, make a config as a *snapshot* while holding a drvdata->lock.
otherwise, we need to change all spinlock usage in sysfs should be
irqsave but it seems much awful.

But I think we can remove it if we move the copy config to active_config
into etm4_enable_sysfs() since there, sysfs_mode is taken. so
active_config could be accessed safely.

I'll move the drvdata->active_config = drvdata->config into 
etm4_enable_sysfs() and will remove this arg.

Thanks!

> 
> >   	int rc;
> >   };
> > @@ -264,10 +265,11 @@ static void etm4x_prohibit_trace(struct etmv4_drvdata *drvdata)
> >   static u64 etm4x_get_kern_user_filter(struct etmv4_drvdata *drvdata)
> >   {
> >   	u64 trfcr = drvdata->trfcr;
> > +	struct etmv4_config *config = &drvdata->active_config;
> > -	if (drvdata->config.mode & ETM_MODE_EXCL_KERN)
> > +	if (config->mode & ETM_MODE_EXCL_KERN)
> >   		trfcr &= ~TRFCR_EL1_ExTRE;
> > -	if (drvdata->config.mode & ETM_MODE_EXCL_USER)
> > +	if (config->mode & ETM_MODE_EXCL_USER)
> >   		trfcr &= ~TRFCR_EL1_E0TRE;
> >   	return trfcr;
> > @@ -275,7 +277,7 @@ static u64 etm4x_get_kern_user_filter(struct etmv4_drvdata *drvdata)
> >   /*
> >    * etm4x_allow_trace - Allow CPU tracing in the respective ELs,
> > - * as configured by the drvdata->config.mode for the current
> > + * as configured by the drvdata->active_config.mode for the current
> >    * session. Even though we have TRCVICTLR bits to filter the
> >    * trace in the ELs, it doesn't prevent the ETM from generating
> >    * a packet (e.g, TraceInfo) that might contain the addresses from
> > @@ -286,12 +288,13 @@ static u64 etm4x_get_kern_user_filter(struct etmv4_drvdata *drvdata)
> >   static void etm4x_allow_trace(struct etmv4_drvdata *drvdata)
> >   {
> >   	u64 trfcr, guest_trfcr;
> > +	struct etmv4_config *config = &drvdata->active_config;
> >   	/* If the CPU doesn't support FEAT_TRF, nothing to do */
> >   	if (!drvdata->trfcr)
> >   		return;
> > -	if (drvdata->config.mode & ETM_MODE_EXCL_HOST)
> > +	if (config->mode & ETM_MODE_EXCL_HOST)
> >   		trfcr = drvdata->trfcr & ~(TRFCR_EL1_ExTRE | TRFCR_EL1_E0TRE);
> >   	else
> >   		trfcr = etm4x_get_kern_user_filter(drvdata);
> > @@ -299,7 +302,7 @@ static void etm4x_allow_trace(struct etmv4_drvdata *drvdata)
> >   	write_trfcr(trfcr);
> >   	/* Set filters for guests and pass to KVM */
> > -	if (drvdata->config.mode & ETM_MODE_EXCL_GUEST)
> > +	if (config->mode & ETM_MODE_EXCL_GUEST)
> >   		guest_trfcr = drvdata->trfcr & ~(TRFCR_EL1_ExTRE | TRFCR_EL1_E0TRE);
> >   	else
> >   		guest_trfcr = etm4x_get_kern_user_filter(drvdata);
> > @@ -492,7 +495,7 @@ static int etm4_enable_trace_unit(struct etmv4_drvdata *drvdata)
> >   static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
> >   {
> >   	int i, rc;
> > -	struct etmv4_config *config = &drvdata->config;
> > +	struct etmv4_config *config = &drvdata->active_config;
> >   	struct coresight_device *csdev = drvdata->csdev;
> >   	struct device *etm_dev = &csdev->dev;
> >   	struct csdev_access *csa = &csdev->access;
> > @@ -612,27 +615,44 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
> >   static void etm4_enable_sysfs_smp_call(void *info)
> >   {
> >   	struct etm4_enable_arg *arg = info;
> > +	struct etmv4_drvdata *drvdata;
> >   	struct coresight_device *csdev;
> > +	unsigned long cfg_hash;
> > +	int preset;
> >   	if (WARN_ON(!arg))
> >   		return;
> > -	csdev = arg->drvdata->csdev;
> > -	if (!coresight_take_mode(csdev, CS_MODE_SYSFS)) {
> > -		/* Someone is already using the tracer */
> > -		arg->rc = -EBUSY;
> > -		return;
> > +	drvdata = arg->drvdata;
> > +	csdev = drvdata->csdev;
> > +
> > +	drvdata->active_config = arg->config;
> 
> This can happen before the smp call removing the need for arg->config?

Yes! That's fair enough :)

> 
> > +
> > +	/* enable any config activated by configfs */
> > +	cscfg_config_sysfs_get_active_cfg(&cfg_hash, &preset);
> > +	if (cfg_hash) {
> > +		arg->rc = cscfg_csdev_enable_active_config(csdev,
> > +							   cfg_hash,
> > +							   preset);
> > +		if (arg->rc)
> > +			return;
> >   	}
> > -	arg->rc = etm4_enable_hw(arg->drvdata);
> > +	drvdata->trcid = arg->path->trace_id;
> > -	/* The tracer didn't start */
> > +	/* Tracer will never be paused in sysfs mode */
> > +	drvdata->paused = false;
> > +
> > +	arg->rc = etm4_enable_hw(drvdata);
> >   	if (arg->rc) {
> > -		coresight_set_mode(csdev, CS_MODE_DISABLED);
> > +		cscfg_csdev_disable_active_config(csdev);
> >   		return;
> >   	}
> > +	drvdata->sticky_enable = true;
> >   	csdev->path = arg->path;
> > +
> > +	return;
> >   }
> >   /*
> > @@ -669,7 +689,7 @@ static int etm4_config_timestamp_event(struct etmv4_drvdata *drvdata,
> >   {
> >   	int ctridx;
> >   	int rselector;
> > -	struct etmv4_config *config = &drvdata->config;
> > +	struct etmv4_config *config = &drvdata->active_config;
> >   	/* No point in trying if we don't have at least one counter */
> >   	if (!drvdata->nr_cntr)
> > @@ -752,7 +772,7 @@ static int etm4_parse_event_config(struct coresight_device *csdev,
> >   {
> >   	int ret = 0;
> >   	struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> > -	struct etmv4_config *config = &drvdata->config;
> > +	struct etmv4_config *config = &drvdata->active_config;
> >   	struct perf_event_attr max_timestamp = {
> >   		.ATTR_CFG_FLD_timestamp_CFG = U64_MAX,
> >   	};
> > @@ -919,46 +939,36 @@ static int etm4_enable_sysfs(struct coresight_device *csdev, struct coresight_pa
> >   {
> >   	struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> >   	struct etm4_enable_arg arg = { };
> > -	unsigned long cfg_hash;
> > -	int ret, preset;
> > +	int ret;
> > -	/* enable any config activated by configfs */
> > -	cscfg_config_sysfs_get_active_cfg(&cfg_hash, &preset);
> > -	if (cfg_hash) {
> > -		ret = cscfg_csdev_enable_active_config(csdev, cfg_hash, preset);
> > -		if (ret) {
> > -			etm4_release_trace_id(drvdata);
> > -			return ret;
> > -		}
> > +	if (!coresight_take_mode(csdev, CS_MODE_SYSFS)) {
> > +		/* Someone is already using the tracer */
> > +		return -EBUSY;
> >   	}
> > -	raw_spin_lock(&drvdata->spinlock);
> > -
> > -	drvdata->trcid = path->trace_id;
> > -
> > -	/* Tracer will never be paused in sysfs mode */
> > -	drvdata->paused = false;
> > -
> >   	/*
> >   	 * Executing etm4_enable_hw on the cpu whose ETM is being enabled
> >   	 * ensures that register writes occur when cpu is powered.
> >   	 */
> >   	arg.drvdata = drvdata;
> >   	arg.path = path;
> > +
> > +	scoped_guard(raw_spinlock, &drvdata->spinlock) {
> > +		arg.config = drvdata->config;
> 
> Given as mentioned above that once a mode is set then active_config is
> protected, this should simply be drvdata->active_config = drvdata->config;
> ??

Right. Here is much better!

> 
> > +	}
> > +
> >   	ret = smp_call_function_single(drvdata->cpu,
> >   				       etm4_enable_sysfs_smp_call, &arg, 1);
> >   	if (!ret)
> >   		ret = arg.rc;
> > -	if (!ret)
> > -		drvdata->sticky_enable = true;
> > -
> > -	if (ret)
> > +	if (!ret) {
> > +		dev_dbg(&csdev->dev, "ETM tracing enabled\n");
> > +	} else {
> >   		etm4_release_trace_id(drvdata);
> > +		/* The tracer didn't start */
> > +		coresight_set_mode(csdev, CS_MODE_DISABLED);
> > +	}
> > -	raw_spin_unlock(&drvdata->spinlock);
> > -
> > -	if (!ret)
> > -		dev_dbg(&csdev->dev, "ETM tracing enabled\n");
> >   	return ret;
> >   }
> > @@ -1044,7 +1054,7 @@ static void etm4_disable_trace_unit(struct etmv4_drvdata *drvdata)
> >   static void etm4_disable_hw(struct etmv4_drvdata *drvdata)
> >   {
> >   	u32 control;
> > -	struct etmv4_config *config = &drvdata->config;
> > +	struct etmv4_config *config = &drvdata->active_config;
> >   	struct coresight_device *csdev = drvdata->csdev;
> >   	struct csdev_access *csa = &csdev->access;
> >   	int i;
> > @@ -1086,8 +1096,9 @@ static void etm4_disable_sysfs_smp_call(void *info)
> >   	etm4_disable_hw(drvdata);
> > +	cscfg_csdev_disable_active_config(drvdata->csdev);
> > +
> >   	drvdata->csdev->path = NULL;
> > -	coresight_set_mode(drvdata->csdev, CS_MODE_DISABLED);
> >   }
> >   static int etm4_disable_perf(struct coresight_device *csdev,
> > @@ -1130,8 +1141,9 @@ static int etm4_disable_perf(struct coresight_device *csdev,
> >   static void etm4_disable_sysfs(struct coresight_device *csdev)
> >   {
> >   	struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> > -
> > -	raw_spin_lock(&drvdata->spinlock);
> > +	struct etmv4_config *config = &drvdata->config;
> > +	const struct etmv4_config *active_config = &drvdata->active_config;
> > +	int i;
> >   	/*
> >   	 * Executing etm4_disable_hw on the cpu whose ETM is being disabled
> > @@ -1140,9 +1152,17 @@ static void etm4_disable_sysfs(struct coresight_device *csdev)
> >   	smp_call_function_single(drvdata->cpu, etm4_disable_sysfs_smp_call,
> >   				 drvdata, 1);
> > -	raw_spin_unlock(&drvdata->spinlock);
> > +	/*
> > +	 * Userspace may read ss_status and cntr_val through sysfs after
> > +	 * the sysfs-session has been disabled.
> > +	 */
> > +	for (i = 0; i < drvdata->nr_ss_cmp; i++)
> > +		config->ss_status[i] = active_config->ss_status[i];
> > -	cscfg_csdev_disable_active_config(csdev);
> > +	for (i = 0; i < drvdata->nr_cntr; i++)
> > +		config->cntr_val[i] = active_config->cntr_val[i];
> > +
> 
> Readback of TRCSEQSTR needed here too.

Right. I've noticted after I post this patch. I'll fix in the next
version. Thanks!

> 
> > +	coresight_set_mode(drvdata->csdev, CS_MODE_DISABLED);
> >   	/*
> >   	 * we only release trace IDs when resetting sysfs.
> > @@ -1690,7 +1710,7 @@ static void etm4_set_default(struct etmv4_config *config)
> >   static int etm4_get_next_comparator(struct etmv4_drvdata *drvdata, u32 type)
> >   {
> >   	int nr_comparator, index = 0;
> > -	struct etmv4_config *config = &drvdata->config;
> > +	struct etmv4_config *config = &drvdata->active_config;
> >   	/*
> >   	 * nr_addr_cmp holds the number of comparator _pair_, so time 2
> > @@ -1731,7 +1751,7 @@ static int etm4_set_event_filters(struct etmv4_drvdata *drvdata,
> >   {
> >   	int i, comparator, ret = 0;
> >   	u64 address;
> > -	struct etmv4_config *config = &drvdata->config;
> > +	struct etmv4_config *config = &drvdata->active_config;
> >   	struct etm_filters *filters = event->hw.addr_filters;
> >   	if (!filters)
> > diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> > index 8d73248b840a6..f64c0acebc701 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> > +++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> > @@ -1613,7 +1613,7 @@ static ssize_t cntr_val_store(struct device *dev,
> >   		return -EINVAL;
> >   	if (val > ETM_CNTR_MAX_VAL)
> >   		return -EINVAL;
> > -	if (coresight_get_mode(drvdata->csdev))
> > +	if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS)
> >   		return -EBUSY;
> >   	raw_spin_lock(&drvdata->spinlock);
> > @@ -1799,7 +1799,7 @@ static ssize_t sshot_ctrl_store(struct device *dev,
> >   	if (kstrtoul(buf, 16, &val))
> >   		return -EINVAL;
> > -	if (coresight_get_mode(drvdata->csdev))
> > +	if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS)
> >   		return -EBUSY;
> >   	raw_spin_lock(&drvdata->spinlock);
> > @@ -1851,7 +1851,7 @@ static ssize_t sshot_pe_ctrl_store(struct device *dev,
> >   	if (kstrtoul(buf, 16, &val))
> >   		return -EINVAL;
> > -	if (coresight_get_mode(drvdata->csdev))
> > +	if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS)
> >   		return -EBUSY;
> >   	raw_spin_lock(&drvdata->spinlock);
> > diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
> > index df9e0748d71ec..c33700711154d 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm4x.h
> > +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
> > @@ -1019,7 +1019,8 @@ struct etmv4_save_state {
> >    *		allows tracing at all ELs. We don't want to compute this
> >    *		at runtime, due to the additional setting of TRFCR_CX when
> >    *		in EL2. Otherwise, 0.
> > - * @config:	structure holding configuration parameters.
> > + * @active_config:	structure holding current applied configuration.
> > + * @config:	structure holding sysfs mode configuration.
> >    * @save_state:	State to be preserved across power loss
> >    * @skip_power_up: Indicates if an implementation can skip powering up
> >    *		   the trace unit.
> > @@ -1077,6 +1078,7 @@ struct etmv4_drvdata {
> >   	bool				skip_power_up : 1;
> >   	bool				paused : 1;
> >   	u64				trfcr;
> > +	struct etmv4_config		active_config;
> >   	struct etmv4_config		config;
> >   	struct etmv4_save_state		*save_state;
> >   	DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
> > 
> 
> Regards
> 
> Mike

Thanks!

-- 
Sincerely,
Yeoreum Yun