[PATCH v3 1/7] perf: Remove duplication around EVENT_SOURCE_DEVICE_PATH

From: James Clark
Date: Tue Jan 03 2023 - 11:22:21 EST

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The pattern for accessing EVENT_SOURCE_DEVICE_PATH is duplicated in a
few places, so add two utility functions to cover it. Also just use
perf_pmu__scan_file() instead of pmu_type() which already does the same
thing.

No functional changes.

Reviewed-by: Leo Yan <leo.yan@xxxxxxxxxx>
Signed-off-by: James Clark <james.clark@xxxxxxx>
---
tools/perf/arch/arm/util/auxtrace.c | 5 +-
tools/perf/arch/x86/util/pmu.c | 12 +--
tools/perf/util/pmu.c | 110 +++++++++++-----------------
tools/perf/util/pmu.h | 5 +-
4 files changed, 49 insertions(+), 83 deletions(-)

diff --git a/tools/perf/arch/arm/util/auxtrace.c b/tools/perf/arch/arm/util/auxtrace.c
index deeb163999ce..adec6c9ee11d 100644
--- a/tools/perf/arch/arm/util/auxtrace.c
+++ b/tools/perf/arch/arm/util/auxtrace.c
@@ -55,17 +55,16 @@ static struct perf_pmu **find_all_arm_spe_pmus(int *nr_spes, int *err)

static struct perf_pmu **find_all_hisi_ptt_pmus(int *nr_ptts, int *err)
{
- const char *sysfs = sysfs__mountpoint();
struct perf_pmu **hisi_ptt_pmus = NULL;
struct dirent *dent;
char path[PATH_MAX];
DIR *dir = NULL;
int idx = 0;

- snprintf(path, PATH_MAX, "%s" EVENT_SOURCE_DEVICE_PATH, sysfs);
+ perf_pmu__event_source_devices_scnprintf(path, sizeof(path));
dir = opendir(path);
if (!dir) {
- pr_err("can't read directory '%s'\n", EVENT_SOURCE_DEVICE_PATH);
+ pr_err("can't read directory '%s'\n", path);
*err = -EINVAL;
return NULL;
}
diff --git a/tools/perf/arch/x86/util/pmu.c b/tools/perf/arch/x86/util/pmu.c
index 74d69db1ea99..358340b34243 100644
--- a/tools/perf/arch/x86/util/pmu.c
+++ b/tools/perf/arch/x86/util/pmu.c
@@ -15,8 +15,6 @@
#include "../../../util/pmu.h"
#include "../../../util/fncache.h"

-#define TEMPLATE_ALIAS "%s/bus/event_source/devices/%s/alias"
-
struct pmu_alias {
char *name;
char *alias;
@@ -72,18 +70,14 @@ static int setup_pmu_alias_list(void)
char path[PATH_MAX];
DIR *dir;
struct dirent *dent;
- const char *sysfs = sysfs__mountpoint();
struct pmu_alias *pmu_alias;
char buf[MAX_PMU_NAME_LEN];
FILE *file;
int ret = -ENOMEM;

- if (!sysfs)
+ if (!perf_pmu__event_source_devices_scnprintf(path, sizeof(path)))
return -1;

- snprintf(path, PATH_MAX,
- "%s" EVENT_SOURCE_DEVICE_PATH, sysfs);
-
dir = opendir(path);
if (!dir)
return -errno;
@@ -93,9 +87,7 @@ static int setup_pmu_alias_list(void)
!strcmp(dent->d_name, ".."))
continue;

- snprintf(path, PATH_MAX,
- TEMPLATE_ALIAS, sysfs, dent->d_name);
-
+ perf_pmu__pathname_scnprintf(path, sizeof(path), dent->d_name, "alias");
if (!file_available(path))
continue;

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 2bdeb89352e7..0d9619dde3a8 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -107,14 +107,10 @@ int perf_pmu__format_parse(char *dir, struct list_head *head)
static int pmu_format(const char *name, struct list_head *format)
{
char path[PATH_MAX];
- const char *sysfs = sysfs__mountpoint();

- if (!sysfs)
+ if (!perf_pmu__pathname_scnprintf(path, sizeof(path), name, "format"))
return -1;

- snprintf(path, PATH_MAX,
- "%s" EVENT_SOURCE_DEVICE_PATH "%s/format", sysfs, name);
-
if (!file_available(path))
return 0;

@@ -513,14 +509,10 @@ static int pmu_aliases_parse(char *dir, struct list_head *head)
static int pmu_aliases(const char *name, struct list_head *head)
{
char path[PATH_MAX];
- const char *sysfs = sysfs__mountpoint();

- if (!sysfs)
+ if (!perf_pmu__pathname_scnprintf(path, sizeof(path), name, "events"))
return -1;

- snprintf(path, PATH_MAX,
- "%s/bus/event_source/devices/%s/events", sysfs, name);
-
if (!file_available(path))
return 0;

@@ -554,52 +546,16 @@ static int pmu_alias_terms(struct perf_pmu_alias *alias,
return 0;
}

-/*
- * Reading/parsing the default pmu type value, which should be
- * located at:
- * /sys/bus/event_source/devices/<dev>/type as sysfs attribute.
- */
-static int pmu_type(const char *name, __u32 *type)
-{
- char path[PATH_MAX];
- FILE *file;
- int ret = 0;
- const char *sysfs = sysfs__mountpoint();
-
- if (!sysfs)
- return -1;
-
- snprintf(path, PATH_MAX,
- "%s" EVENT_SOURCE_DEVICE_PATH "%s/type", sysfs, name);
-
- if (access(path, R_OK) < 0)
- return -1;
-
- file = fopen(path, "r");
- if (!file)
- return -EINVAL;
-
- if (1 != fscanf(file, "%u", type))
- ret = -1;
-
- fclose(file);
- return ret;
-}
-
/* Add all pmus in sysfs to pmu list: */
static void pmu_read_sysfs(void)
{
char path[PATH_MAX];
DIR *dir;
struct dirent *dent;
- const char *sysfs = sysfs__mountpoint();

- if (!sysfs)
+ if (!perf_pmu__event_source_devices_scnprintf(path, sizeof(path)))
return;

- snprintf(path, PATH_MAX,
- "%s" EVENT_SOURCE_DEVICE_PATH, sysfs);
-
dir = opendir(path);
if (!dir)
return;
@@ -696,14 +652,9 @@ static char *pmu_id(const char *name)
static int is_arm_pmu_core(const char *name)
{
char path[PATH_MAX];
- const char *sysfs = sysfs__mountpoint();

- if (!sysfs)
+ if (!perf_pmu__pathname_scnprintf(path, sizeof(path), name, "cpus"))
return 0;
-
- /* Look for cpu sysfs (specific to arm) */
- scnprintf(path, PATH_MAX, "%s/bus/event_source/devices/%s/cpus",
- sysfs, name);
return file_available(path);
}

@@ -969,11 +920,8 @@ static struct perf_pmu *pmu_lookup(const char *lookup_name)
return NULL;

/*
- * Check the type first to avoid unnecessary work.
+ * Check the aliases first to avoid unnecessary work.
*/
- if (pmu_type(name, &type))
- return NULL;
-
if (pmu_aliases(name, &aliases))
return NULL;

@@ -983,9 +931,14 @@ static struct perf_pmu *pmu_lookup(const char *lookup_name)

pmu->cpus = pmu_cpumask(name);
pmu->name = strdup(name);
+
if (!pmu->name)
goto err;

+ /* Read type, and ensure that type value is successfully assigned (return 1) */
+ if (perf_pmu__scan_file(pmu, "type", "%u", &type) != 1)
+ goto err;
+
alias_name = pmu_find_alias_name(name);
if (alias_name) {
pmu->alias_name = strdup(alias_name);
@@ -1786,16 +1739,11 @@ bool pmu_have_event(const char *pname, const char *name)
static FILE *perf_pmu__open_file(struct perf_pmu *pmu, const char *name)
{
char path[PATH_MAX];
- const char *sysfs;

- sysfs = sysfs__mountpoint();
- if (!sysfs)
+ if (!perf_pmu__pathname_scnprintf(path, sizeof(path), pmu->name, name) ||
+ !file_available(path))
return NULL;

- snprintf(path, PATH_MAX,
- "%s" EVENT_SOURCE_DEVICE_PATH "%s/%s", sysfs, pmu->name, name);
- if (!file_available(path))
- return NULL;
return fopen(path, "r");
}

@@ -1849,7 +1797,6 @@ int perf_pmu__caps_parse(struct perf_pmu *pmu)
{
struct stat st;
char caps_path[PATH_MAX];
- const char *sysfs = sysfs__mountpoint();
DIR *caps_dir;
struct dirent *evt_ent;

@@ -1858,12 +1805,9 @@ int perf_pmu__caps_parse(struct perf_pmu *pmu)

pmu->nr_caps = 0;

- if (!sysfs)
+ if (!perf_pmu__pathname_scnprintf(caps_path, sizeof(caps_path), pmu->name, "caps"))
return -1;

- snprintf(caps_path, PATH_MAX,
- "%s" EVENT_SOURCE_DEVICE_PATH "%s/caps", sysfs, pmu->name);
-
if (stat(caps_path, &st) < 0) {
pmu->caps_initialized = true;
return 0; /* no error if caps does not exist */
@@ -1993,3 +1937,31 @@ int perf_pmu__cpus_match(struct perf_pmu *pmu, struct perf_cpu_map *cpus,
*ucpus_ptr = unmatched_cpus;
return 0;
}
+
+int perf_pmu__event_source_devices_scnprintf(char *pathname, size_t size)
+{
+ const char *sysfs = sysfs__mountpoint();
+
+ if (!sysfs)
+ return 0;
+ return scnprintf(pathname, size, "%s/bus/event_source/devices/", sysfs);
+}
+
+/*
+ * Fill 'buf' with the path to a file or folder in 'pmu_name' in
+ * sysfs. For example if pmu_name = "cs_etm" and 'filename' = "format"
+ * then pathname will be filled with
+ * "/sys/bus/event_source/devices/cs_etm/format"
+ *
+ * Return 0 if the sysfs mountpoint couldn't be found or if no
+ * characters were written.
+ */
+int perf_pmu__pathname_scnprintf(char *buf, size_t size,
+ const char *pmu_name, const char *filename)
+{
+ char base_path[PATH_MAX];
+
+ if (!perf_pmu__event_source_devices_scnprintf(base_path, sizeof(base_path)))
+ return 0;
+ return scnprintf(buf, size, "%s%s/%s", base_path, pmu_name, filename);
+}
diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 69ca0004f94f..2f2bb0286e2a 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -22,7 +22,6 @@ enum {
};

#define PERF_PMU_FORMAT_BITS 64
-#define EVENT_SOURCE_DEVICE_PATH "/bus/event_source/devices/"
#define CPUS_TEMPLATE_CPU "%s/bus/event_source/devices/%s/cpus"
#define MAX_PMU_NAME_LEN 128

@@ -259,4 +258,8 @@ int perf_pmu__cpus_match(struct perf_pmu *pmu, struct perf_cpu_map *cpus,

char *pmu_find_real_name(const char *name);
char *pmu_find_alias_name(const char *name);
+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);
+
#endif /* __PMU_H */
--
2.25.1

Next message: James Clark: "[PATCH v3 0/7] perf cs_etm: Basic support for virtual/kernel timestamps"
Previous message: Eddie James: "[PATCH] tpm: Add reserved memory event log"
In reply to: James Clark: "[PATCH v3 0/7] perf cs_etm: Basic support for virtual/kernel timestamps"
Next in thread: James Clark: "[PATCH v3 2/7] perf: Use perf_pmu__open_file() and perf_pmu__scan_file()"
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