linux/tools/perf/tests/pmu.c
Namhyung Kim e293a5e816 perf pmu: Use relative path for sysfs scan
The PMU information is in the kernel sysfs so it needs to scan the
directory to get the whole information like event aliases, formats and
so on.  During the traversal, it opens a lot of files and directories
like below:

  dir = opendir("/sys/bus/event_source/devices");
  while (dentry = readdir(dir)) {
    char buf[PATH_MAX];

    snprintf(buf, sizeof(buf), "%s/%s",
             "/sys/bus/event_source/devices", dentry->d_name);
    fd = open(buf, O_RDONLY);
    ...
  }

But this is not good since it needs to copy the string to build the
absolute pathname, and it makes redundant pathname walk (from the /sys)
unnecessarily.  We can use openat(2) to open the file in the given
directory.  While it's not a problem ususally, it can be a problem when
the kernel has contentions on the sysfs.

Add a couple of new helper to return the file descriptor of PMU
directory so that it can use it with relative paths.

 * perf_pmu__event_source_devices_fd()
   - returns a fd for the PMU root ("/sys/bus/event_source/devices")

 * perf_pmu__pathname_fd()
   - returns a fd for "<pmu>/<file>" under the PMU root

Now the above code can be converted something like below:

  dirfd = perf_pmu__event_source_devices_fd();
  dir = fdopendir(dirfd);
  while (dentry = readdir(dir)) {
    fd = openat(dirfd, dentry->d_name, O_RDONLY);
    ...
  }

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230331202949.810326-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-04-04 13:23:58 -03:00

189 lines
4.1 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include "parse-events.h"
#include "pmu.h"
#include "tests.h"
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <linux/kernel.h>
#include <linux/limits.h>
/* Simulated format definitions. */
static struct test_format {
const char *name;
const char *value;
} test_formats[] = {
{ "krava01", "config:0-1,62-63\n", },
{ "krava02", "config:10-17\n", },
{ "krava03", "config:5\n", },
{ "krava11", "config1:0,2,4,6,8,20-28\n", },
{ "krava12", "config1:63\n", },
{ "krava13", "config1:45-47\n", },
{ "krava21", "config2:0-3,10-13,20-23,30-33,40-43,50-53,60-63\n", },
{ "krava22", "config2:8,18,48,58\n", },
{ "krava23", "config2:28-29,38\n", },
};
/* Simulated users input. */
static struct parse_events_term test_terms[] = {
{
.config = (char *) "krava01",
.val.num = 15,
.type_val = PARSE_EVENTS__TERM_TYPE_NUM,
.type_term = PARSE_EVENTS__TERM_TYPE_USER,
},
{
.config = (char *) "krava02",
.val.num = 170,
.type_val = PARSE_EVENTS__TERM_TYPE_NUM,
.type_term = PARSE_EVENTS__TERM_TYPE_USER,
},
{
.config = (char *) "krava03",
.val.num = 1,
.type_val = PARSE_EVENTS__TERM_TYPE_NUM,
.type_term = PARSE_EVENTS__TERM_TYPE_USER,
},
{
.config = (char *) "krava11",
.val.num = 27,
.type_val = PARSE_EVENTS__TERM_TYPE_NUM,
.type_term = PARSE_EVENTS__TERM_TYPE_USER,
},
{
.config = (char *) "krava12",
.val.num = 1,
.type_val = PARSE_EVENTS__TERM_TYPE_NUM,
.type_term = PARSE_EVENTS__TERM_TYPE_USER,
},
{
.config = (char *) "krava13",
.val.num = 2,
.type_val = PARSE_EVENTS__TERM_TYPE_NUM,
.type_term = PARSE_EVENTS__TERM_TYPE_USER,
},
{
.config = (char *) "krava21",
.val.num = 119,
.type_val = PARSE_EVENTS__TERM_TYPE_NUM,
.type_term = PARSE_EVENTS__TERM_TYPE_USER,
},
{
.config = (char *) "krava22",
.val.num = 11,
.type_val = PARSE_EVENTS__TERM_TYPE_NUM,
.type_term = PARSE_EVENTS__TERM_TYPE_USER,
},
{
.config = (char *) "krava23",
.val.num = 2,
.type_val = PARSE_EVENTS__TERM_TYPE_NUM,
.type_term = PARSE_EVENTS__TERM_TYPE_USER,
},
};
/*
* Prepare format directory data, exported by kernel
* at /sys/bus/event_source/devices/<dev>/format.
*/
static char *test_format_dir_get(void)
{
static char dir[PATH_MAX];
unsigned int i;
snprintf(dir, PATH_MAX, "/tmp/perf-pmu-test-format-XXXXXX");
if (!mkdtemp(dir))
return NULL;
for (i = 0; i < ARRAY_SIZE(test_formats); i++) {
static char name[PATH_MAX];
struct test_format *format = &test_formats[i];
FILE *file;
scnprintf(name, PATH_MAX, "%s/%s", dir, format->name);
file = fopen(name, "w");
if (!file)
return NULL;
if (1 != fwrite(format->value, strlen(format->value), 1, file))
break;
fclose(file);
}
return dir;
}
/* Cleanup format directory. */
static int test_format_dir_put(char *dir)
{
char buf[PATH_MAX];
snprintf(buf, PATH_MAX, "rm -f %s/*\n", dir);
if (system(buf))
return -1;
snprintf(buf, PATH_MAX, "rmdir %s\n", dir);
return system(buf);
}
static struct list_head *test_terms_list(void)
{
static LIST_HEAD(terms);
unsigned int i;
for (i = 0; i < ARRAY_SIZE(test_terms); i++)
list_add_tail(&test_terms[i].list, &terms);
return &terms;
}
static int test__pmu(struct test_suite *test __maybe_unused, int subtest __maybe_unused)
{
char *format = test_format_dir_get();
LIST_HEAD(formats);
struct list_head *terms = test_terms_list();
int ret;
if (!format)
return -EINVAL;
do {
struct perf_event_attr attr;
int fd;
memset(&attr, 0, sizeof(attr));
fd = open(format, O_DIRECTORY);
if (fd < 0) {
ret = fd;
break;
}
ret = perf_pmu__format_parse(fd, &formats);
if (ret)
break;
ret = perf_pmu__config_terms("perf-pmu-test", &formats, &attr,
terms, false, NULL);
if (ret)
break;
ret = -EINVAL;
if (attr.config != 0xc00000000002a823)
break;
if (attr.config1 != 0x8000400000000145)
break;
if (attr.config2 != 0x0400000020041d07)
break;
ret = 0;
} while (0);
perf_pmu__del_formats(&formats);
test_format_dir_put(format);
return ret;
}
DEFINE_SUITE("Parse perf pmu format", pmu);