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Date:   Fri, 20 Jan 2023 14:21:56 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     James Clark <james.clark@arm.com>
Cc:     linux-perf-users@vger.kernel.org, tanmay@marvell.com,
        leo.yan@linaro.org, mike.leach@linaro.org, sgoutham@marvell.com,
        gcherian@marvell.com, lcherian@marvell.com, bbhushan2@marvell.com,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        John Garry <john.g.garry@oracle.com>,
        Will Deacon <will@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>, coresight@lists.linaro.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 2/8] perf: Use perf_pmu__open_file() and
 perf_pmu__scan_file()
Message-ID: <Y8rNtO5HNcPJDpQ2@kernel.org>
References: <20230120143702.4035046-1-james.clark@arm.com>
 <20230120143702.4035046-3-james.clark@arm.com>
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In-Reply-To: <20230120143702.4035046-3-james.clark@arm.com>
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Em Fri, Jan 20, 2023 at 02:36:55PM +0000, James Clark escreveu:
> Remove some code that duplicates existing methods. Copy strings where
> const strings are required.
> 
> No functional changes.


Have you used 'perf test'?

[acme@quaco perf]$ perf test -v python
Couldn't bump rlimit(MEMLOCK), failures may take place when creating BPF maps, etc
 19: 'import perf' in python                                         :
--- start ---
test child forked, pid 232379
python usage test: "echo "import sys ; sys.path.append('/tmp/build/perf/python'); import perf" | '/usr/bin/python3' "
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: /tmp/build/perf/python/perf.cpython-310-x86_64-linux-gnu.so: undefined symbol: perf_pmu__scan_file
test child finished with -1
---- end ----
'import perf' in python: FAILED!
[acme@quaco perf]$
 
> Reviewed-by: Leo Yan <leo.yan@linaro.org>
> Signed-off-by: James Clark <james.clark@arm.com>
> ---
>  tools/perf/util/cputopo.c    |  9 +-------
>  tools/perf/util/pmu-hybrid.c | 27 +++++-------------------
>  tools/perf/util/pmu.c        | 40 +++++++++++-------------------------
>  tools/perf/util/pmu.h        |  3 ++-
>  4 files changed, 20 insertions(+), 59 deletions(-)
> 
> diff --git a/tools/perf/util/cputopo.c b/tools/perf/util/cputopo.c
> index 1a3ff6449158..e08797c3cdbc 100644
> --- a/tools/perf/util/cputopo.c
> +++ b/tools/perf/util/cputopo.c
> @@ -422,8 +422,6 @@ void numa_topology__delete(struct numa_topology *tp)
>  static int load_hybrid_node(struct hybrid_topology_node *node,
>  			    struct perf_pmu *pmu)
>  {
> -	const char *sysfs;
> -	char path[PATH_MAX];
>  	char *buf = NULL, *p;
>  	FILE *fp;
>  	size_t len = 0;
> @@ -432,12 +430,7 @@ static int load_hybrid_node(struct hybrid_topology_node *node,
>  	if (!node->pmu_name)
>  		return -1;
>  
> -	sysfs = sysfs__mountpoint();
> -	if (!sysfs)
> -		goto err;
> -
> -	snprintf(path, PATH_MAX, CPUS_TEMPLATE_CPU, sysfs, pmu->name);
> -	fp = fopen(path, "r");
> +	fp = perf_pmu__open_file(pmu, "cpus");
>  	if (!fp)
>  		goto err;
>  
> diff --git a/tools/perf/util/pmu-hybrid.c b/tools/perf/util/pmu-hybrid.c
> index f51ccaac60ee..38628805a952 100644
> --- a/tools/perf/util/pmu-hybrid.c
> +++ b/tools/perf/util/pmu-hybrid.c
> @@ -20,32 +20,15 @@ LIST_HEAD(perf_pmu__hybrid_pmus);
>  
>  bool perf_pmu__hybrid_mounted(const char *name)
>  {
> -	char path[PATH_MAX];
> -	const char *sysfs;
> -	FILE *file;
> -	int n, cpu;
> +	int cpu;
> +	char pmu_name[PATH_MAX];
> +	struct perf_pmu pmu = {.name = pmu_name};
>  
>  	if (strncmp(name, "cpu_", 4))
>  		return false;
>  
> -	sysfs = sysfs__mountpoint();
> -	if (!sysfs)
> -		return false;
> -
> -	snprintf(path, PATH_MAX, CPUS_TEMPLATE_CPU, sysfs, name);
> -	if (!file_available(path))
> -		return false;
> -
> -	file = fopen(path, "r");
> -	if (!file)
> -		return false;
> -
> -	n = fscanf(file, "%u", &cpu);
> -	fclose(file);
> -	if (n <= 0)
> -		return false;
> -
> -	return true;
> +	strlcpy(pmu_name, name, sizeof(pmu_name));
> +	return perf_pmu__scan_file(&pmu, "cpus", "%u", &cpu) > 0;
>  }
>  
>  struct perf_pmu *perf_pmu__find_hybrid_pmu(const char *name)
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 1edbb714ff32..a771a5972fc5 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -571,45 +571,31 @@ static void pmu_read_sysfs(void)
>  	closedir(dir);
>  }
>  
> -static struct perf_cpu_map *__pmu_cpumask(const char *path)
> -{
> -	FILE *file;
> -	struct perf_cpu_map *cpus;
> -
> -	file = fopen(path, "r");
> -	if (!file)
> -		return NULL;
> -
> -	cpus = perf_cpu_map__read(file);
> -	fclose(file);
> -	return cpus;
> -}
> -
>  /*
>   * Uncore PMUs have a "cpumask" file under sysfs. CPU PMUs (e.g. on arm/arm64)
>   * may have a "cpus" file.
>   */
>  #define SYS_TEMPLATE_ID	"./bus/event_source/devices/%s/identifier"
> -#define CPUS_TEMPLATE_UNCORE	"%s/bus/event_source/devices/%s/cpumask"
>  
>  static struct perf_cpu_map *pmu_cpumask(const char *name)
>  {
> -	char path[PATH_MAX];
>  	struct perf_cpu_map *cpus;
> -	const char *sysfs = sysfs__mountpoint();
>  	const char *templates[] = {
> -		CPUS_TEMPLATE_UNCORE,
> -		CPUS_TEMPLATE_CPU,
> +		"cpumask",
> +		"cpus",
>  		NULL
>  	};
>  	const char **template;
> +	char pmu_name[PATH_MAX];
> +	struct perf_pmu pmu = {.name = pmu_name};
> +	FILE *file;
>  
> -	if (!sysfs)
> -		return NULL;
> -
> +	strlcpy(pmu_name, name, sizeof(pmu_name));
>  	for (template = templates; *template; template++) {
> -		snprintf(path, PATH_MAX, *template, sysfs, name);
> -		cpus = __pmu_cpumask(path);
> +		file = perf_pmu__open_file(&pmu, *template);
> +		if (!file)
> +			continue;
> +		cpus = perf_cpu_map__read(file);
>  		if (cpus)
>  			return cpus;
>  	}
> @@ -620,13 +606,11 @@ static struct perf_cpu_map *pmu_cpumask(const char *name)
>  static bool pmu_is_uncore(const char *name)
>  {
>  	char path[PATH_MAX];
> -	const char *sysfs;
>  
>  	if (perf_pmu__hybrid_mounted(name))
>  		return false;
>  
> -	sysfs = sysfs__mountpoint();
> -	snprintf(path, PATH_MAX, CPUS_TEMPLATE_UNCORE, sysfs, name);
> +	perf_pmu__pathname_scnprintf(path, sizeof(path), name, "cpumask");
>  	return file_available(path);
>  }
>  
> @@ -1737,7 +1721,7 @@ bool pmu_have_event(const char *pname, const char *name)
>  	return false;
>  }
>  
> -static FILE *perf_pmu__open_file(struct perf_pmu *pmu, const char *name)
> +FILE *perf_pmu__open_file(struct perf_pmu *pmu, const char *name)
>  {
>  	char path[PATH_MAX];
>  
> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> index 96d030c8b3b3..742d4db319a0 100644
> --- a/tools/perf/util/pmu.h
> +++ b/tools/perf/util/pmu.h
> @@ -7,6 +7,7 @@
>  #include <linux/perf_event.h>
>  #include <linux/list.h>
>  #include <stdbool.h>
> +#include <stdio.h>
>  #include "parse-events.h"
>  #include "pmu-events/pmu-events.h"
>  
> @@ -22,7 +23,6 @@ enum {
>  };
>  
>  #define PERF_PMU_FORMAT_BITS 64
> -#define CPUS_TEMPLATE_CPU	"%s/bus/event_source/devices/%s/cpus"
>  #define MAX_PMU_NAME_LEN 128
>  
>  struct perf_event_attr;
> @@ -262,5 +262,6 @@ double perf_pmu__cpu_slots_per_cycle(void);
>  int perf_pmu__event_source_devices_scnprintf(char *pathname, size_t size);
>  int perf_pmu__pathname_scnprintf(char *buf, size_t size,
>  				 const char *pmu_name, const char *filename);
> +FILE *perf_pmu__open_file(struct perf_pmu *pmu, const char *name);
>  
>  #endif /* __PMU_H */
> -- 
> 2.25.1
> 

-- 

- Arnaldo