C++ (Cpp) prealloc_elems_and_freelist示例

示例#1

文件： stackmap.c 项目： ReneNyffenegger/linux

/* Called from syscall */
static struct bpf_map *stack_map_alloc(union bpf_attr *attr)
{
	u32 value_size = attr->value_size;
	struct bpf_stack_map *smap;
	u64 cost, n_buckets;
	int err;

	if (!capable(CAP_SYS_ADMIN))
		return ERR_PTR(-EPERM);

	if (attr->map_flags & ~STACK_CREATE_FLAG_MASK)
		return ERR_PTR(-EINVAL);

	/* check sanity of attributes */
	if (attr->max_entries == 0 || attr->key_size != 4 ||
	    value_size < 8 || value_size % 8 ||
	    value_size / 8 > sysctl_perf_event_max_stack)
		return ERR_PTR(-EINVAL);

	/* hash table size must be power of 2 */
	n_buckets = roundup_pow_of_two(attr->max_entries);

	cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap);
	if (cost >= U32_MAX - PAGE_SIZE)
		return ERR_PTR(-E2BIG);

	smap = bpf_map_area_alloc(cost, bpf_map_attr_numa_node(attr));
	if (!smap)
		return ERR_PTR(-ENOMEM);

	err = -E2BIG;
	cost += n_buckets * (value_size + sizeof(struct stack_map_bucket));
	if (cost >= U32_MAX - PAGE_SIZE)
		goto free_smap;

	bpf_map_init_from_attr(&smap->map, attr);
	smap->map.value_size = value_size;
	smap->n_buckets = n_buckets;
	smap->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT;

	err = bpf_map_precharge_memlock(smap->map.pages);
	if (err)
		goto free_smap;

	err = get_callchain_buffers(sysctl_perf_event_max_stack);
	if (err)
		goto free_smap;

	err = prealloc_elems_and_freelist(smap);
	if (err)
		goto put_buffers;

	return &smap->map;

put_buffers:
	put_callchain_buffers();
free_smap:
	bpf_map_area_free(smap);
	return ERR_PTR(err);
}

示例#2

文件： stackmap.c 项目： 020gzh/linux

/* Called from syscall */
static struct bpf_map *stack_map_alloc(union bpf_attr *attr)
{
	u32 value_size = attr->value_size;
	struct bpf_stack_map *smap;
	u64 cost, n_buckets;
	int err;

	if (!capable(CAP_SYS_ADMIN))
		return ERR_PTR(-EPERM);

	if (attr->map_flags)
		return ERR_PTR(-EINVAL);

	/* check sanity of attributes */
	if (attr->max_entries == 0 || attr->key_size != 4 ||
	    value_size < 8 || value_size % 8 ||
	    value_size / 8 > PERF_MAX_STACK_DEPTH)
		return ERR_PTR(-EINVAL);

	/* hash table size must be power of 2 */
	n_buckets = roundup_pow_of_two(attr->max_entries);

	cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap);
	if (cost >= U32_MAX - PAGE_SIZE)
		return ERR_PTR(-E2BIG);

	smap = kzalloc(cost, GFP_USER | __GFP_NOWARN);
	if (!smap) {
		smap = vzalloc(cost);
		if (!smap)
			return ERR_PTR(-ENOMEM);
	}

	err = -E2BIG;
	cost += n_buckets * (value_size + sizeof(struct stack_map_bucket));
	if (cost >= U32_MAX - PAGE_SIZE)
		goto free_smap;

	smap->map.map_type = attr->map_type;
	smap->map.key_size = attr->key_size;
	smap->map.value_size = value_size;
	smap->map.max_entries = attr->max_entries;
	smap->n_buckets = n_buckets;
	smap->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT;

	err = bpf_map_precharge_memlock(smap->map.pages);
	if (err)
		goto free_smap;

	err = get_callchain_buffers();
	if (err)
		goto free_smap;

	err = prealloc_elems_and_freelist(smap);
	if (err)
		goto put_buffers;

	return &smap->map;

put_buffers:
	put_callchain_buffers();
free_smap:
	kvfree(smap);
	return ERR_PTR(err);
}