Subject: Re: [PATCH v3] coresight: etm3x: Fix cntr_val_show() to match cntr_val_store() behavior

From: Kuan-Wei Chiu <[email-masked]>
Date: Fri, 3 Apr 2026 16:57:53 +0800

Hi Suzuki,

On Mon, Feb 02, 2026 at 09:33:59AM +0000, Suzuki K Poulose wrote:
> Hello
> 
> On 02/02/2026 05:09, Kuan-Wei Chiu wrote:
> > On Tue, Dec 02, 2025 at 09:26:19AM +0000, James Clark wrote:
> > > 
> > > 
> > > On 02/12/2025 8:26 am, Kuan-Wei Chiu wrote:
> > > > The cntr_val_show() function was intended to print the values of all
> > > > counters using a loop. However, due to a buffer overwrite issue with
> > > > sprintf(), it effectively only displayed the value of the last counter.
> > > > 
> > > > The companion function, cntr_val_store(), allows users to modify a
> > > > specific counter selected by 'cntr_idx'. To maintain consistency
> > > > between read and write operations and to align with the ETM4x driver
> > > > behavior, modify cntr_val_show() to report only the value of the
> > > > currently selected counter.
> > > > 
> > > > This change removes the loop and the "counter %d:" prefix, printing
> > > > only the hexadecimal value. It also adopts sysfs_emit() for standard
> > > > sysfs output formatting.
> > > > 
> > > > Fixes: a939fc5a71ad ("coresight-etm: add CoreSight ETM/PTM driver")
> > > > Cc: [email-masked]
> > > > Signed-off-by: Kuan-Wei Chiu <[email-masked]>
> > > > ---
> > > > Build test only.
> > > > 
> > > > Changes in v3:
> > > > - Switch format specifier to %#x to include the 0x prefix.
> > > > - Add Cc stable
> > > > 
> > > > v2: https://lore.kernel.org/lkml/[email-masked]/
> > > > 
> > > >    .../hwtracing/coresight/coresight-etm3x-sysfs.c   | 15 ++++-----------
> > > >    1 file changed, 4 insertions(+), 11 deletions(-)
> > > > 
> > > > diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> > > > index 762109307b86..b3c67e96a82a 100644
> > > > --- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> > > > +++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> > > > @@ -717,26 +717,19 @@ static DEVICE_ATTR_RW(cntr_rld_event);
> > > >    static ssize_t cntr_val_show(struct device *dev,
> > > >    			     struct device_attribute *attr, char *buf)
> > > >    {
> > > > -	int i, ret = 0;
> > > >    	u32 val;
> > > >    	struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);
> > > >    	struct etm_config *config = &drvdata->config;
> > > >    	if (!coresight_get_mode(drvdata->csdev)) {
> > > >    		spin_lock(&drvdata->spinlock);
> > > > -		for (i = 0; i < drvdata->nr_cntr; i++)
> > > > -			ret += sprintf(buf, "counter %d: %x\n",
> > > > -				       i, config->cntr_val[i]);
> > > > +		val = config->cntr_val[config->cntr_idx];
> > > >    		spin_unlock(&drvdata->spinlock);
> > > > -		return ret;
> > > > -	}
> > > > -
> > > > -	for (i = 0; i < drvdata->nr_cntr; i++) {
> > > > -		val = etm_readl(drvdata, ETMCNTVRn(i));
> > > > -		ret += sprintf(buf, "counter %d: %x\n", i, val);
> > > > +	} else {
> > > > +		val = etm_readl(drvdata, ETMCNTVRn(config->cntr_idx));
> > > >    	}
> > > > -	return ret;
> > > > +	return sysfs_emit(buf, "%#x\n", val);
> > > >    }
> > > >    static ssize_t cntr_val_store(struct device *dev,
> > > 
> > > Reviewed-by: James Clark <[email-masked]>
> > > 
> > Thanks for the review!
> > Is there anything else I need to do for this fix to land?
> 
> Thanks for the patch, I will queue this for the next release (v7.1).
>
Just a gentle ping.

Since the v7.1 merge window is presumably opening in about a week, I
noticed this patch isn't in linux-next yet and wanted to send a quick
reminder. Thanks.

Regards,
Kuan-Wei