Re: [PATCH v2 11/23] coresight: trbe: Assign the perf handle in enable and disable

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

On 16/10/2026 17:55, Leo Yan wrote:
> etm-perf owns the perf output handle embedded in its per-CPU etm_ctxt and
> passes it to TRBE through arm_trbe_enable(). TRBE binds that handle after
> successful sink enable and unbinds it in arm_trbe_disable(). The handle
> object remains valid throughout this interval, even if the current AUX
> transaction ends or a new transaction begins.
> 
> The inner enable helper currently publishes the handle, while truncation
> and failed rollover clear it. Sink disable leaves the handle installed
> after dropping the buffer association. These assignments track the AUX
> transaction rather than the enabled sink session.
> 
> Publish the handle only in arm_trbe_enable() after successful setup and
> clear it in arm_trbe_disable() before dropping the buffer association.
> Remove the assignments from the inner enable, overflow and truncation
> paths so the handle association follows the enabled sink session.
> 
> A valid handle object may have no active AUX transaction, so the IRQ
> handler continues to check perf_get_aux() before accessing the
> transaction's configuration.
> 
> Signed-off-by: Leo Yan <leo.yan@arm.com>
> ---
>   drivers/hwtracing/coresight/coresight-trbe.c | 20 +++++++-------------
>   1 file changed, 7 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
> index 4a041bbc6e970d72a7d735e15f7221037cb091d6..1f51c33de83638479436683fd96e31d69c3b860f 100644
> --- a/drivers/hwtracing/coresight/coresight-trbe.c
> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
> @@ -303,11 +303,8 @@ static void trbe_report_wrap_event(struct perf_output_handle *handle)
>   
>   static void trbe_truncate_event(struct perf_output_handle *handle)
>   {
> -	struct trbe_buf *buf = etm_perf_sink_config(handle);
> -
>   	perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
>   	perf_aux_output_end(handle, 0);
> -	*this_cpu_ptr(buf->cpudata->drvdata->handle) = NULL;
>   }
>   
>   /*
> @@ -1012,7 +1009,6 @@ static int __arm_trbe_enable(struct trbe_buf *buf,
>   	if (ret)
>   		goto err;
>   
> -	*this_cpu_ptr(buf->cpudata->drvdata->handle) = handle;
>   	trbe_enable_hw(buf);
>   	return 0;
>   err:
> @@ -1042,6 +1038,7 @@ static int arm_trbe_enable(struct coresight_device *csdev, enum cs_mode mode,
>   		return ret;
>   	}
>   
> +	*this_cpu_ptr(drvdata->handle) = handle;
>   	cpudata->buf = buf;
>   	cpudata->mode = mode;
>   	return 0;
> @@ -1062,6 +1059,7 @@ static int arm_trbe_disable(struct coresight_device *csdev)
>   	trbe_drain_and_disable_local(cpudata);
>   	clr_trbe_status();
>   
> +	*this_cpu_ptr(drvdata->handle) = NULL;
>   	buf->cpudata = NULL;
>   	cpudata->buf = NULL;
>   	cpudata->mode = CS_MODE_DISABLED;
> @@ -1102,16 +1100,12 @@ static int trbe_handle_overflow(struct perf_output_handle *handle)
>   	trbe_report_wrap_event(handle);
>   	perf_aux_output_end(handle, size);
>   	event_data = perf_aux_output_begin(handle, event);
> -	if (!event_data) {
> -		/*
> -		 * We are unable to restart the trace collection,
> -		 * thus leave the TRBE disabled. The etm-perf driver
> -		 * is able to detect this with a disconnected handle
> -		 * (handle->event = NULL).
> -		 */
> -		*this_cpu_ptr(buf->cpudata->drvdata->handle) = NULL;
> +	/*
> +	 * If trace collection cannot be restarted, leave TRBE disabled.
> +	 * The etm-perf driver detects this through handle->event == NULL.
> +	 */
> +	if (!event_data)
>   		return -EINVAL;
> -	}
>   
>   	return __arm_trbe_enable(buf, handle);
>   }
> 
Reviewed-by: James Clark <james.clark@linaro.org>