linux/tools/perf/lib/cpumap.c

// SPDX-License-Identifier: GPL-2.0-only
#include <perf/cpumap.h>
#include <stdlib.h>
#include <linux/refcount.h>
#include <internal/cpumap.h>
#include <asm/bug.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>
#include <limits.h>

struct perf_cpu_map *perf_cpu_map__dummy_new(void)
{
	struct perf_cpu_map *cpus = malloc(sizeof(*cpus) + sizeof(int));

	if (cpus != NULL) {
		cpus->nr = 1;
		cpus->map[0] = -1;
		refcount_set(&cpus->refcnt, 1);
	}

	return cpus;
}

static void cpu_map__delete(struct perf_cpu_map *map)
{
	if (map) {
		WARN_ONCE(refcount_read(&map->refcnt) != 0,
			  "cpu_map refcnt unbalanced\n");
		free(map);
	}
}

struct perf_cpu_map *perf_cpu_map__get(struct perf_cpu_map *map)
{
	if (map)
		refcount_inc(&map->refcnt);
	return map;
}

void perf_cpu_map__put(struct perf_cpu_map *map)
{
	if (map && refcount_dec_and_test(&map->refcnt))
		cpu_map__delete(map);
}

static struct perf_cpu_map *cpu_map__default_new(void)
{
	struct perf_cpu_map *cpus;
	int nr_cpus;

	nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
	if (nr_cpus < 0)
		return NULL;

	cpus = malloc(sizeof(*cpus) + nr_cpus * sizeof(int));
	if (cpus != NULL) {
		int i;

		for (i = 0; i < nr_cpus; ++i)
			cpus->map[i] = i;

		cpus->nr = nr_cpus;
		refcount_set(&cpus->refcnt, 1);
	}

	return cpus;
}

static struct perf_cpu_map *cpu_map__trim_new(int nr_cpus, int *tmp_cpus)
{
	size_t payload_size = nr_cpus * sizeof(int);
	struct perf_cpu_map *cpus = malloc(sizeof(*cpus) + payload_size);

	if (cpus != NULL) {
		cpus->nr = nr_cpus;
		memcpy(cpus->map, tmp_cpus, payload_size);
		refcount_set(&cpus->refcnt, 1);
	}

	return cpus;
}

struct perf_cpu_map *perf_cpu_map__read(FILE *file)
{
	struct perf_cpu_map *cpus = NULL;
	int nr_cpus = 0;
	int *tmp_cpus = NULL, *tmp;
	int max_entries = 0;
	int n, cpu, prev;
	char sep;

	sep = 0;
	prev = -1;
	for (;;) {
		n = fscanf(file, "%u%c", &cpu, &sep);
		if (n <= 0)
			break;
		if (prev >= 0) {
			int new_max = nr_cpus + cpu - prev - 1;

			if (new_max >= max_entries) {
				max_entries = new_max + MAX_NR_CPUS / 2;
				tmp = realloc(tmp_cpus, max_entries * sizeof(int));
				if (tmp == NULL)
					goto out_free_tmp;
				tmp_cpus = tmp;
			}

			while (++prev < cpu)
				tmp_cpus[nr_cpus++] = prev;
		}
		if (nr_cpus == max_entries) {
			max_entries += MAX_NR_CPUS;
			tmp = realloc(tmp_cpus, max_entries * sizeof(int));
			if (tmp == NULL)
				goto out_free_tmp;
			tmp_cpus = tmp;
		}

		tmp_cpus[nr_cpus++] = cpu;
		if (n == 2 && sep == '-')
			prev = cpu;
		else
			prev = -1;
		if (n == 1 || sep == '\n')
			break;
	}

	if (nr_cpus > 0)
		cpus = cpu_map__trim_new(nr_cpus, tmp_cpus);
	else
		cpus = cpu_map__default_new();
out_free_tmp:
	free(tmp_cpus);
	return cpus;
}

static struct perf_cpu_map *cpu_map__read_all_cpu_map(void)
{
	struct perf_cpu_map *cpus = NULL;
	FILE *onlnf;

	onlnf = fopen("/sys/devices/system/cpu/online", "r");
	if (!onlnf)
		return cpu_map__default_new();

	cpus = perf_cpu_map__read(onlnf);
	fclose(onlnf);
	return cpus;
}

struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
{
	struct perf_cpu_map *cpus = NULL;
	unsigned long start_cpu, end_cpu = 0;
	char *p = NULL;
	int i, nr_cpus = 0;
	int *tmp_cpus = NULL, *tmp;
	int max_entries = 0;

	if (!cpu_list)
		return cpu_map__read_all_cpu_map();

	/*
	 * must handle the case of empty cpumap to cover
	 * TOPOLOGY header for NUMA nodes with no CPU
	 * ( e.g., because of CPU hotplug)
	 */
	if (!isdigit(*cpu_list) && *cpu_list != '\0')
		goto out;

	while (isdigit(*cpu_list)) {
		p = NULL;
		start_cpu = strtoul(cpu_list, &p, 0);
		if (start_cpu >= INT_MAX
		    || (*p != '\0' && *p != ',' && *p != '-'))
			goto invalid;

		if (*p == '-') {
			cpu_list = ++p;
			p = NULL;
			end_cpu = strtoul(cpu_list, &p, 0);

			if (end_cpu >= INT_MAX || (*p != '\0' && *p != ','))
				goto invalid;

			if (end_cpu < start_cpu)
				goto invalid;
		} else {
			end_cpu = start_cpu;
		}

		for (; start_cpu <= end_cpu; start_cpu++) {
			/* check for duplicates */
			for (i = 0; i < nr_cpus; i++)
				if (tmp_cpus[i] == (int)start_cpu)
					goto invalid;

			if (nr_cpus == max_entries) {
				max_entries += MAX_NR_CPUS;
				tmp = realloc(tmp_cpus, max_entries * sizeof(int));
				if (tmp == NULL)
					goto invalid;
				tmp_cpus = tmp;
			}
			tmp_cpus[nr_cpus++] = (int)start_cpu;
		}
		if (*p)
			++p;

		cpu_list = p;
	}

	if (nr_cpus > 0)
		cpus = cpu_map__trim_new(nr_cpus, tmp_cpus);
	else if (*cpu_list != '\0')
		cpus = cpu_map__default_new();
	else
		cpus = perf_cpu_map__dummy_new();
invalid:
	free(tmp_cpus);
out:
	return cpus;
}

int perf_cpu_map__cpu(const struct perf_cpu_map *cpus, int idx)
{
	if (idx < cpus->nr)
		return cpus->map[idx];

	return -1;
}

int perf_cpu_map__nr(const struct perf_cpu_map *cpus)
{
	return cpus ? cpus->nr : 1;
}