diff mbox series

[v2,4/7] perf pmu: Add function to check if a pmu file exists

Message ID 20221222160328.3639989-5-james.clark@arm.com
State New
Headers
Series perf cs_etm: Basic support for virtual/kernel timestamps |

Commit Message

James Clark Dec. 22, 2022, 4:03 p.m. UTC 
  From: German Gomez <german.gomez@arm.com>

Add a utility function perf_pmu__file_exists() to check if a given pmu
file exists in the sysfs filesystem.

Signed-off-by: German Gomez <german.gomez@arm.com>
Signed-off-by: James Clark <james.clark@arm.com>
---
 tools/perf/util/pmu.c | 14 ++++++++++++++
 tools/perf/util/pmu.h |  2 ++
 2 files changed, 16 insertions(+)

Comments

Leo Yan Dec. 23, 2022, 6:26 a.m. UTC | #1 
On Thu, Dec 22, 2022 at 04:03:24PM +0000, James Clark wrote:
> From: German Gomez <german.gomez@arm.com>
> 
> Add a utility function perf_pmu__file_exists() to check if a given pmu
> file exists in the sysfs filesystem.
> 
> Signed-off-by: German Gomez <german.gomez@arm.com>
> Signed-off-by: James Clark <james.clark@arm.com>
> ---
>  tools/perf/util/pmu.c | 14 ++++++++++++++
>  tools/perf/util/pmu.h |  2 ++
>  2 files changed, 16 insertions(+)
> 
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 15b852b3c401..b72b2d892949 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -1739,6 +1739,20 @@ int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt,
>  	return ret;
>  }
>  
> +bool perf_pmu__file_exists(struct perf_pmu *pmu, const char *name)
> +{
> +	char path[PATH_MAX];
> +	struct stat statbuf;
> +
> +	if (!perf_pmu__pathname_scnprintf(path, PATH_MAX, pmu->name, name))
> +		return false;
> +
> +	if (!file_available(path))
> +		return false;
> +
> +	return stat(path, &statbuf) == 0;

Can we simply return the returned value from file_available() and skip
calling stat()?  Because file_available() invokes access() to detect if
a file is existed or not, so here calling stat() is redundant.

Thanks,
Leo

> +}
> +
>  static int perf_pmu__new_caps(struct list_head *list, char *name, char *value)
>  {
>  	struct perf_pmu_caps *caps = zalloc(sizeof(*caps));
> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> index 8f39e2d17fb1..c1d138fe9602 100644
> --- a/tools/perf/util/pmu.h
> +++ b/tools/perf/util/pmu.h
> @@ -230,6 +230,8 @@ bool pmu_have_event(const char *pname, const char *name);
>  
>  int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt, ...) __scanf(3, 4);
>  
> +bool perf_pmu__file_exists(struct perf_pmu *pmu, const char *name);
> +
>  int perf_pmu__test(void);
>  
>  struct perf_event_attr *perf_pmu__get_default_config(struct perf_pmu *pmu);
> -- 
> 2.25.1
>
James Clark Jan. 3, 2023, 4:22 p.m. UTC | #2 
On 23/12/2022 06:26, Leo Yan wrote:
> On Thu, Dec 22, 2022 at 04:03:24PM +0000, James Clark wrote:
>> From: German Gomez <german.gomez@arm.com>
>>
>> Add a utility function perf_pmu__file_exists() to check if a given pmu
>> file exists in the sysfs filesystem.
>>
>> Signed-off-by: German Gomez <german.gomez@arm.com>
>> Signed-off-by: James Clark <james.clark@arm.com>
>> ---
>>  tools/perf/util/pmu.c | 14 ++++++++++++++
>>  tools/perf/util/pmu.h |  2 ++
>>  2 files changed, 16 insertions(+)
>>
>> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
>> index 15b852b3c401..b72b2d892949 100644
>> --- a/tools/perf/util/pmu.c
>> +++ b/tools/perf/util/pmu.c
>> @@ -1739,6 +1739,20 @@ int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt,
>>  	return ret;
>>  }
>>  
>> +bool perf_pmu__file_exists(struct perf_pmu *pmu, const char *name)
>> +{
>> +	char path[PATH_MAX];
>> +	struct stat statbuf;
>> +
>> +	if (!perf_pmu__pathname_scnprintf(path, PATH_MAX, pmu->name, name))
>> +		return false;
>> +
>> +	if (!file_available(path))
>> +		return false;
>> +
>> +	return stat(path, &statbuf) == 0;
> 
> Can we simply return the returned value from file_available() and skip
> calling stat()?  Because file_available() invokes access() to detect if
> a file is existed or not, so here calling stat() is redundant.
> 

Yep that works. Fixed in V3.
diff mbox series

Patch

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 15b852b3c401..b72b2d892949 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -1739,6 +1739,20 @@  int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt,
 	return ret;
 }
 
+bool perf_pmu__file_exists(struct perf_pmu *pmu, const char *name)
+{
+	char path[PATH_MAX];
+	struct stat statbuf;
+
+	if (!perf_pmu__pathname_scnprintf(path, PATH_MAX, pmu->name, name))
+		return false;
+
+	if (!file_available(path))
+		return false;
+
+	return stat(path, &statbuf) == 0;
+}
+
 static int perf_pmu__new_caps(struct list_head *list, char *name, char *value)
 {
 	struct perf_pmu_caps *caps = zalloc(sizeof(*caps));
diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 8f39e2d17fb1..c1d138fe9602 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -230,6 +230,8 @@  bool pmu_have_event(const char *pname, const char *name);
 
 int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt, ...) __scanf(3, 4);
 
+bool perf_pmu__file_exists(struct perf_pmu *pmu, const char *name);
+
 int perf_pmu__test(void);
 
 struct perf_event_attr *perf_pmu__get_default_config(struct perf_pmu *pmu);