linux-kernel - Re: [PATCH v5 13/17] coresight: Make CPU id map a property of a trace ID map

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Message-ID: <CAJ9a7Vg-L+Csx15G_sNci3koMhZY6g95_pAiFgormmdbvWw9hQ@mail.gmail.com>
Date: Wed, 17 Jul 2024 16:03:16 +0100
From: Mike Leach <mike.leach@...aro.org>
To: James Clark <james.clark@...aro.org>
Cc: coresight@...ts.linaro.org, suzuki.poulose@....com, 
	gankulkarni@...amperecomputing.com, leo.yan@...ux.dev, 
	anshuman.khandual@....com, James Clark <james.clark@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, 
	Maxime Coquelin <mcoquelin.stm32@...il.com>, Alexandre Torgue <alexandre.torgue@...s.st.com>, 
	John Garry <john.g.garry@...cle.com>, Will Deacon <will@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>, 
	Adrian Hunter <adrian.hunter@...el.com>, "Liang, Kan" <kan.liang@...ux.intel.com>, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-stm32@...md-mailman.stormreply.com, linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v5 13/17] coresight: Make CPU id map a property of a trace
 ID map

On Fri, 12 Jul 2024 at 11:23, James Clark <james.clark@...aro.org> wrote:
>
> From: James Clark <james.clark@....com>
>
> 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@....com>
> Signed-off-by: James Clark <james.clark@...aro.org>
> ---
>  drivers/hwtracing/coresight/coresight-trace-id.c | 16 +++++++++-------
>  include/linux/coresight.h                        |  1 +
>  2 files changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-trace-id.c b/drivers/hwtracing/coresight/coresight-trace-id.c
> index 5561989a03fa..8a777c0af6ea 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 */
> @@ -49,7 +51,7 @@ static void coresight_trace_id_dump_table(struct coresight_trace_id_map *id_map,
>  /* unlocked read of current trace ID value for given CPU */
>  static int _coresight_trace_id_read_cpu_id(int cpu, struct coresight_trace_id_map *id_map)
>  {
> -       return atomic_read(&per_cpu(cpu_id, cpu));
> +       return atomic_read(per_cpu_ptr(id_map->cpu_map, cpu));
>  }
>
>  /* look for next available odd ID, return 0 if none found */
> @@ -145,7 +147,7 @@ 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);
> @@ -181,7 +183,7 @@ static int _coresight_trace_id_get_cpu_id(int cpu, struct coresight_trace_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 */
> @@ -215,7 +217,7 @@ static void _coresight_trace_id_put_cpu_id(int cpu, struct coresight_trace_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);
> 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;
>  };
>
>  /**
> --
> 2.34.1
>

Reviewed-by: Mike Leach <mike.leach@...aro.org>


--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK