Re: [PATCH 12/17] coresight: Make CPU id map a property of a trace ID map

[Anshuman Khandual <anshuman.khandual@arm.com>]

On 4/29/24 20:51, James Clark wrote:
> The global CPU ID mappings won't work for per-sink ID maps so move it to
> the ID map struct. coresight_trace_id_release_all_pending() is hard
> coded to operate on the default map, but once Perf sessions use their
> own maps the pending release mechanism will be deleted. So it doesn't
> need to be extended to accept a trace ID map argument at this point.
> 
> Signed-off-by: James Clark <james.clark@arm.com>
> ---
>  .../hwtracing/coresight/coresight-etm-perf.c  |  3 +-
>  .../coresight/coresight-etm3x-core.c          |  3 +-
>  .../coresight/coresight-etm4x-core.c          |  3 +-
>  .../hwtracing/coresight/coresight-trace-id.c  | 28 ++++++++-----------
>  .../hwtracing/coresight/coresight-trace-id.h  |  2 +-
>  include/linux/coresight.h                     |  1 +
>  6 files changed, 20 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
> index 4afb9d29f355..25f1f87c90d1 100644
> --- a/drivers/hwtracing/coresight/coresight-etm-perf.c
> +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
> @@ -508,7 +508,8 @@ static void etm_event_start(struct perf_event *event, int flags)
>  		hw_id = FIELD_PREP(CS_AUX_HW_ID_VERSION_MASK,
>  				   CS_AUX_HW_ID_CURR_VERSION);
>  		hw_id |= FIELD_PREP(CS_AUX_HW_ID_TRACE_ID_MASK,
> -				    coresight_trace_id_read_cpu_id(cpu));
> +				    coresight_trace_id_read_cpu_id(cpu,
> +						coresight_trace_id_map_default()));
>  		perf_report_aux_output_id(event, hw_id);
>  	}
>  
> diff --git a/drivers/hwtracing/coresight/coresight-etm3x-core.c b/drivers/hwtracing/coresight/coresight-etm3x-core.c
> index 4149e7675ceb..b21f5ad94e63 100644
> --- a/drivers/hwtracing/coresight/coresight-etm3x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c
> @@ -501,7 +501,8 @@ static int etm_enable_perf(struct coresight_device *csdev,
>  	 * with perf locks - we know the ID cannot change until perf shuts down
>  	 * the session
>  	 */
> -	trace_id = coresight_trace_id_read_cpu_id(drvdata->cpu);
> +	trace_id = coresight_trace_id_read_cpu_id(drvdata->cpu,
> +						  coresight_trace_id_map_default());
>  	if (!IS_VALID_CS_TRACE_ID(trace_id)) {
>  		dev_err(&drvdata->csdev->dev, "Failed to set trace ID for %s on CPU%d\n",
>  			dev_name(&drvdata->csdev->dev), drvdata->cpu);
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index f32c8cd7742d..d16d6efb26fa 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -776,7 +776,8 @@ static int etm4_enable_perf(struct coresight_device *csdev,
>  	 * with perf locks - we know the ID cannot change until perf shuts down
>  	 * the session
>  	 */
> -	trace_id = coresight_trace_id_read_cpu_id(drvdata->cpu);
> +	trace_id = coresight_trace_id_read_cpu_id(drvdata->cpu,
> +						  coresight_trace_id_map_default());
>  	if (!IS_VALID_CS_TRACE_ID(trace_id)) {
>  		dev_err(&drvdata->csdev->dev, "Failed to set trace ID for %s on CPU%d\n",
>  			dev_name(&drvdata->csdev->dev), drvdata->cpu);
> diff --git a/drivers/hwtracing/coresight/coresight-trace-id.c b/drivers/hwtracing/coresight/coresight-trace-id.c
> index 45ddd50d09a6..b393603dd713 100644
> --- a/drivers/hwtracing/coresight/coresight-trace-id.c
> +++ b/drivers/hwtracing/coresight/coresight-trace-id.c
> @@ -13,10 +13,12 @@
>  #include "coresight-trace-id.h"
>  
>  /* Default trace ID map. Used in sysfs mode and for system sources */
> -static struct coresight_trace_id_map id_map_default;
> +static DEFINE_PER_CPU(atomic_t, id_map_default_cpu_ids) = ATOMIC_INIT(0);
> +static struct coresight_trace_id_map id_map_default = {
> +	.cpu_map = &id_map_default_cpu_ids
> +};
>  
> -/* maintain a record of the mapping of IDs and pending releases per cpu */
> -static DEFINE_PER_CPU(atomic_t, cpu_id) = ATOMIC_INIT(0);
> +/* maintain a record of the pending releases per cpu */
>  static cpumask_t cpu_id_release_pending;
>  
>  /* perf session active counter */
> @@ -46,12 +48,6 @@ static void coresight_trace_id_dump_table(struct coresight_trace_id_map *id_map,
>  #define PERF_SESSION(n)
>  #endif
>  
> -/* unlocked read of current trace ID value for given CPU */
> -static int _coresight_trace_id_read_cpu_id(int cpu)
> -{
> -	return atomic_read(&per_cpu(cpu_id, cpu));
> -}

Just wondering where this per cpu cpu_id ^^ is being dropped off as well
OR is it still getting used ?

> -
>  /* look for next available odd ID, return 0 if none found */
>  static int coresight_trace_id_find_odd_id(struct coresight_trace_id_map *id_map)
>  {
> @@ -145,7 +141,7 @@ static void coresight_trace_id_release_all_pending(void)
>  		clear_bit(bit, id_map->pend_rel_ids);
>  	}
>  	for_each_cpu(cpu, &cpu_id_release_pending) {
> -		atomic_set(&per_cpu(cpu_id, cpu), 0);
> +		atomic_set(per_cpu_ptr(id_map_default.cpu_map, cpu), 0);
>  		cpumask_clear_cpu(cpu, &cpu_id_release_pending);
>  	}
>  	spin_unlock_irqrestore(&id_map_lock, flags);
> @@ -160,7 +156,7 @@ int coresight_trace_id_get_cpu_id(int cpu, struct coresight_trace_id_map *id_map
>  	spin_lock_irqsave(&id_map_lock, flags);
>  
>  	/* check for existing allocation for this CPU */
> -	id = _coresight_trace_id_read_cpu_id(cpu);
> +	id = coresight_trace_id_read_cpu_id(cpu, id_map);
>  	if (id)
>  		goto get_cpu_id_clr_pend;
>  
> @@ -181,7 +177,7 @@ int coresight_trace_id_get_cpu_id(int cpu, struct coresight_trace_id_map *id_map
>  		goto get_cpu_id_out_unlock;
>  
>  	/* allocate the new id to the cpu */
> -	atomic_set(&per_cpu(cpu_id, cpu), id);
> +	atomic_set(per_cpu_ptr(id_map->cpu_map, cpu), id);
>  
>  get_cpu_id_clr_pend:
>  	/* we are (re)using this ID - so ensure it is not marked for release */
> @@ -203,7 +199,7 @@ void coresight_trace_id_put_cpu_id(int cpu, struct coresight_trace_id_map *id_ma
>  	int id;
>  
>  	/* check for existing allocation for this CPU */
> -	id = _coresight_trace_id_read_cpu_id(cpu);
> +	id = coresight_trace_id_read_cpu_id(cpu, id_map);
>  	if (!id)
>  		return;
>  
> @@ -216,7 +212,7 @@ void coresight_trace_id_put_cpu_id(int cpu, struct coresight_trace_id_map *id_ma
>  	} else {
>  		/* otherwise clear id */
>  		coresight_trace_id_free(id, id_map);
> -		atomic_set(&per_cpu(cpu_id, cpu), 0);
> +		atomic_set(per_cpu_ptr(id_map->cpu_map, cpu), 0);
>  	}
>  
>  	spin_unlock_irqrestore(&id_map_lock, flags);
> @@ -258,9 +254,9 @@ struct coresight_trace_id_map *coresight_trace_id_map_default(void)
>  }
>  EXPORT_SYMBOL_GPL(coresight_trace_id_map_default);
>  
> -int coresight_trace_id_read_cpu_id(int cpu)
> +int coresight_trace_id_read_cpu_id(int cpu, struct coresight_trace_id_map *id_map)
>  {
> -	return _coresight_trace_id_read_cpu_id(cpu);
> +	return atomic_read(per_cpu_ptr(id_map->cpu_map, cpu));
>  }
>  EXPORT_SYMBOL_GPL(coresight_trace_id_read_cpu_id);
>  
> diff --git a/drivers/hwtracing/coresight/coresight-trace-id.h b/drivers/hwtracing/coresight/coresight-trace-id.h
> index 54b9d8ed903b..ed2bc4b3ad2a 100644
> --- a/drivers/hwtracing/coresight/coresight-trace-id.h
> +++ b/drivers/hwtracing/coresight/coresight-trace-id.h
> @@ -93,7 +93,7 @@ void coresight_trace_id_put_cpu_id(int cpu, struct coresight_trace_id_map *id_ma
>   *
>   * return: current value, will be 0 if unallocated.
>   */
> -int coresight_trace_id_read_cpu_id(int cpu);
> +int coresight_trace_id_read_cpu_id(int cpu, struct coresight_trace_id_map *id_map);
>  
>  /**
>   * Allocate a CoreSight trace ID for a system component.
> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> index c16c61a8411d..7d62b88bfb5c 100644
> --- a/include/linux/coresight.h
> +++ b/include/linux/coresight.h
> @@ -234,6 +234,7 @@ struct coresight_sysfs_link {
>  struct coresight_trace_id_map {
>  	DECLARE_BITMAP(used_ids, CORESIGHT_TRACE_IDS_MAX);
>  	DECLARE_BITMAP(pend_rel_ids, CORESIGHT_TRACE_IDS_MAX);
> +	atomic_t __percpu *cpu_map;
>  };
>  
>  /**