1. 根目录:
2. tools
3. perf
4. tests
5. keep-tracking.c

#include <linux/types.h>
#include <unistd.h>
#include <sys/prctl.h>

#include "parse-events.h"
#include "evlist.h"
#include "evsel.h"
#include "thread_map.h"
#include "cpumap.h"
#include "tests.h"

#define CHECK__(x) {				\
	while ((x) < 0) {			\
		pr_debug(#x " failed!\n");	\
		goto out_err;			\
	}					\
}

#define CHECK_NOT_NULL__(x) {			\
	while ((x) == NULL) {			\
		pr_debug(#x " failed!\n");	\
		goto out_err;			\
	}					\
}

static int find_comm(struct perf_evlist *evlist, const char *comm)
{
	union perf_event *event;
	int i, found;

	found = 0;
	for (i = 0; i < evlist->nr_mmaps; i++) {
		while ((event = perf_evlist__mmap_read(evlist, i)) != NULL) {
			if (event->header.type == PERF_RECORD_COMM &&
			    (pid_t)event->comm.pid == getpid() &&
			    (pid_t)event->comm.tid == getpid() &&
			    strcmp(event->comm.comm, comm) == 0)
				found += 1;
			perf_evlist__mmap_consume(evlist, i);
		}
	}
	return found;
}

/**
 * test__keep_tracking - test using a dummy software event to keep tracking.
 *
 * This function implements a test that checks that tracking events continue
 * when an event is disabled but a dummy software event is not disabled.  If the
 * test passes %0 is returned, otherwise %-1 is returned.
 */
int test__keep_tracking(void)
{
	struct record_opts opts = {
		.mmap_pages	     = UINT_MAX,
		.user_freq	     = UINT_MAX,
		.user_interval	     = ULLONG_MAX,
		.freq		     = 4000,
		.target		     = {
			.uses_mmap   = true,
		},
	};
	struct thread_map *threads = NULL;
	struct cpu_map *cpus = NULL;
	struct perf_evlist *evlist = NULL;
	struct perf_evsel *evsel = NULL;
	int found, err = -1;
	const char *comm;

	threads = thread_map__new(-1, getpid(), UINT_MAX);
	CHECK_NOT_NULL__(threads);

	cpus = cpu_map__new(NULL);
	CHECK_NOT_NULL__(cpus);

	evlist = perf_evlist__new();
	CHECK_NOT_NULL__(evlist);

	perf_evlist__set_maps(evlist, cpus, threads);

	CHECK__(parse_events(evlist, "dummy:u"));
	CHECK__(parse_events(evlist, "cycles:u"));

	perf_evlist__config(evlist, &opts);

	evsel = perf_evlist__first(evlist);

	evsel->attr.comm = 1;
	evsel->attr.disabled = 1;
	evsel->attr.enable_on_exec = 0;

	if (perf_evlist__open(evlist) < 0) {
		fprintf(stderr, " (not supported)");
		err = 0;
		goto out_err;
	}

	CHECK__(perf_evlist__mmap(evlist, UINT_MAX, false));

	/*
	 * First, test that a 'comm' event can be found when the event is
	 * enabled.
	 */

	perf_evlist__enable(evlist);

	comm = "Test COMM 1";
	CHECK__(prctl(PR_SET_NAME, (unsigned long)comm, 0, 0, 0));

	perf_evlist__disable(evlist);

	found = find_comm(evlist, comm);
	if (found != 1) {
		pr_debug("First time, failed to find tracking event.\n");
		goto out_err;
	}

	/*
	 * Secondly, test that a 'comm' event can be found when the event is
	 * disabled with the dummy event still enabled.
	 */

	perf_evlist__enable(evlist);

	evsel = perf_evlist__last(evlist);

	CHECK__(perf_evlist__disable_event(evlist, evsel));

	comm = "Test COMM 2";
	CHECK__(prctl(PR_SET_NAME, (unsigned long)comm, 0, 0, 0));

	perf_evlist__disable(evlist);

	found = find_comm(evlist, comm);
	if (found != 1) {
		pr_debug("Seconf time, failed to find tracking event.\n");
		goto out_err;
	}

	err = 0;

out_err:
	if (evlist) {
		perf_evlist__disable(evlist);
		perf_evlist__delete(evlist);
	} else {
		cpu_map__delete(cpus);
		thread_map__delete(threads);
	}

	return err;
}