Re: [PATCH v2 07/23] coresight: trbe: Publish the session after successful enable

[James Clark <james.clark@linaro.org>]

On 16/10/2026 17:55, Leo Yan wrote:
> arm_trbe_enable() records the session buffer and perf mode before
> __arm_trbe_enable() can fail. CoreSight skips the sink disable callback
> when sink enable fails, leaving that session state published even though
> tracing did not start.
> 
> Install buf->cpudata temporarily for the buffer setup helpers, then call
> __arm_trbe_enable() before assigning cpudata->buf and cpudata->mode.
> Clear the temporary buffer association if setup fails; the inner helper
> still truncates and ends the AUX transaction.
> 
> After successful enable, retain the buffer association across AUX
> transactions and clear it in arm_trbe_disable().
> 
> Signed-off-by: Leo Yan <leo.yan@arm.com>
> ---
>   drivers/hwtracing/coresight/coresight-trbe.c | 15 ++++++++++++---
>   1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
> index 979d0fa84c1c7b448c1ce5cd7a37dff8845795ef..9dfc6bb7afb4c42dfdec643ee7e4f2f193e2b70c 100644
> --- a/drivers/hwtracing/coresight/coresight-trbe.c
> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
> @@ -69,6 +69,7 @@ struct trbe_buf {
>   	int nr_pages;
>   	void **pages;
>   	bool snapshot;
> +	/* CPU used to configure this buffer. */
>   	struct trbe_cpudata *cpudata;
>   };
>   
> @@ -137,6 +138,7 @@ struct trbe_save_state {
>    * @trbe_align		- Software alignment used for the TRBPTR_EL1.
>    * @cpu			- CPU this TRBE belongs to.
>    * @mode		- Mode of current operation. (perf/disabled)
> + * @buf			- Buffer configuration retained for the enabled session.
>    * @drvdata		- TRBE specific drvdata
>    * @errata		- Bit map for the errata on this TRBE.
>    */
> @@ -1033,17 +1035,24 @@ static int arm_trbe_enable(struct coresight_device *csdev, enum cs_mode mode,
>   	struct trbe_cpudata *cpudata = dev_get_drvdata(&csdev->dev);
>   	struct perf_output_handle *handle = path->handle;
>   	struct trbe_buf *buf = etm_perf_sink_config(handle);
> +	int ret;
>   
>   	WARN_ON(cpudata->cpu != smp_processor_id());
>   	WARN_ON(cpudata->drvdata != drvdata);
>   	if (mode != CS_MODE_PERF)
>   		return -EINVAL;
>   
> -	cpudata->buf = buf;
> -	cpudata->mode = mode;
> +	/* Buffer helpers need the CPU association while setting up tracing. */
>   	buf->cpudata = cpudata;
> +	ret = __arm_trbe_enable(buf, handle);
> +	if (ret) {
> +		buf->cpudata = NULL;
> +		return ret;
> +	}
>   
> -	return __arm_trbe_enable(buf, handle);
> +	cpudata->buf = buf;
> +	cpudata->mode = mode;
> +	return 0;
>   }
>   
>   static int arm_trbe_disable(struct coresight_device *csdev)
> 
Reviewed-by: James Clark <james.clark@linaro.org>