Re: [PATCH v14 05/10] Coresight: Allocate trace ID after building the path

[Jie Gan <quic_jiegan@xxxxxxxxxxx>]

On 2/26/2025 12:13 PM, Jie Gan wrote:
> The trace_id will be stored in coresight_path instead of being declared
> everywhere and allocated after building the path.
>
> Signed-off-by: Jie Gan <quic_jiegan@xxxxxxxxxxx>

Correct tags:
Co-developed-by: James Clark <james.clark@xxxxxxxxxx>
Signed-off-by: James Clark <james.clark@xxxxxxxxxx>
Signed-off-by: Jie Gan <quic_jiegan@xxxxxxxxxxx>

Jie

> ---
>   drivers/hwtracing/coresight/coresight-core.c  | 44 +++++++++++++++++++
>   .../hwtracing/coresight/coresight-etm-perf.c  |  5 +--
>   drivers/hwtracing/coresight/coresight-priv.h  |  2 +
>   drivers/hwtracing/coresight/coresight-sysfs.c |  4 ++
>   4 files changed, 52 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> index 9c2a088a28d8..7d010d996f01 100644
> --- a/drivers/hwtracing/coresight/coresight-core.c
> +++ b/drivers/hwtracing/coresight/coresight-core.c
> @@ -654,6 +654,50 @@ static void coresight_drop_device(struct coresight_device *csdev)
>   	}
>   }
>   
> +/*
> + * coresight device will read their existing or alloc a trace ID, if their trace_id
> + * callback is set.
> + *
> + * Return 0 if the trace_id callback is not set.
> + * Return the result of the trace_id callback if it is set. The return value
> + * will be the trace_id if successful, and an error number if it fails.
> + */
> +static int coresight_get_trace_id(struct coresight_device *csdev,
> +				  enum cs_mode mode,
> +				  struct coresight_device *sink)
> +{
> +	if (coresight_ops(csdev)->trace_id)
> +		return coresight_ops(csdev)->trace_id(csdev, mode, sink);
> +
> +	return 0;
> +}
> +
> +/*
> + * Call this after creating the path and before enabling it. This leaves
> + * the trace ID set on the path, or it remains 0 if it couldn't be assigned.
> + */
> +void coresight_path_assign_trace_id(struct coresight_path *path,
> +				    enum cs_mode mode)
> +{
> +	struct coresight_device *sink = coresight_get_sink(&path->path_list);
> +	struct coresight_node *nd;
> +	int trace_id;
> +
> +	list_for_each_entry(nd, &path->path_list, link) {
> +		/* 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 in this context is that it didn't want to assign so keep searching.
> +		 * Non 0 is either success or fail.
> +		*/
> +		if (trace_id != 0) {
> +			path->trace_id = trace_id;
> +			return;
> +		}
> +	}
> +}
> +
>   /**
>    * _coresight_build_path - recursively build a path from a @csdev to a sink.
>    * @csdev:	The device to start from.
> diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
> index b0426792f08a..134290ab622e 100644
> --- a/drivers/hwtracing/coresight/coresight-etm-perf.c
> +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
> @@ -319,7 +319,6 @@ static void *etm_setup_aux(struct perf_event *event, void **pages,
>   {
>   	u32 id, cfg_hash;
>   	int cpu = event->cpu;
> -	int trace_id;
>   	cpumask_t *mask;
>   	struct coresight_device *sink = NULL;
>   	struct coresight_device *user_sink = NULL, *last_sink = NULL;
> @@ -409,8 +408,8 @@ static void *etm_setup_aux(struct perf_event *event, void **pages,
>   		}
>   
>   		/* ensure we can allocate a trace ID for this CPU */
> -		trace_id = coresight_trace_id_get_cpu_id_map(cpu, &sink->perf_sink_id_map);
> -		if (!IS_VALID_CS_TRACE_ID(trace_id)) {
> +		coresight_path_assign_trace_id(path, CS_MODE_PERF);
> +		if (!IS_VALID_CS_TRACE_ID(path->trace_id)) {
>   			cpumask_clear_cpu(cpu, mask);
>   			coresight_release_path(path);
>   			continue;
> diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
> index 27b7dc348d4a..2bea35bae0d4 100644
> --- a/drivers/hwtracing/coresight/coresight-priv.h
> +++ b/drivers/hwtracing/coresight/coresight-priv.h
> @@ -152,6 +152,8 @@ int coresight_make_links(struct coresight_device *orig,
>   void coresight_remove_links(struct coresight_device *orig,
>   			    struct coresight_connection *conn);
>   u32 coresight_get_sink_id(struct coresight_device *csdev);
> +void coresight_path_assign_trace_id(struct coresight_path *path,
> +				   enum cs_mode mode);
>   
>   #if IS_ENABLED(CONFIG_CORESIGHT_SOURCE_ETM3X)
>   extern int etm_readl_cp14(u32 off, unsigned int *val);
> diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c
> index cb4c39732d26..d03751bf3d8a 100644
> --- a/drivers/hwtracing/coresight/coresight-sysfs.c
> +++ b/drivers/hwtracing/coresight/coresight-sysfs.c
> @@ -209,6 +209,10 @@ int coresight_enable_sysfs(struct coresight_device *csdev)
>   		goto out;
>   	}
>   
> +	coresight_path_assign_trace_id(path, CS_MODE_SYSFS);
> +	if (!IS_VALID_CS_TRACE_ID(path->trace_id))
> +		goto err_path;
> +
>   	ret = coresight_enable_path(&path->path_list, CS_MODE_SYSFS, NULL);
>   	if (ret)
>   		goto err_path;