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Date:   Fri, 20 Jan 2023 14:32:30 -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: <Y8rQLirdlgU8nMEW@kernel.org>
References: <20230120143702.4035046-1-james.clark@arm.com>
 <20230120143702.4035046-3-james.clark@arm.com>
 <Y8rNtO5HNcPJDpQ2@kernel.org>
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Em Fri, Jan 20, 2023 at 02:21:56PM -0300, Arnaldo Carvalho de Melo escreveu:
> 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]$

I added this to this cset, now it passes.

diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index d948455e5ed43656..9e5d881b098767a3 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -20,6 +20,7 @@
 #include "stat.h"
 #include "metricgroup.h"
 #include "util/env.h"
+#include "util/pmu.h"
 #include <internal/lib.h>
 #include "util.h"
 
@@ -83,7 +84,7 @@ void perf_stat__collect_metric_expr(struct evlist *evsel_list)
 }
 
 /*
- * This one is needed not to drag the PMU bandwagon, jevents generated
+ * These ones are needed not to drag the PMU bandwagon, jevents generated
  * pmu_sys_event_tables, etc and evsel__find_pmu() is used so far just for
  * doing per PMU perf_event_attr.exclude_guest handling, not really needed, so
  * far, for the perf python binding known usecases, revisit if this become
@@ -94,6 +95,11 @@ struct perf_pmu *evsel__find_pmu(struct evsel *evsel __maybe_unused)
 	return NULL;
 }
 
+int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt, ...)
+{
+	return EOF;
+}
+
 /*
  * Add this one here not to drag util/metricgroup.c
  */
  
> > 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

-- 

- Arnaldo