static int dm_stats_create()

in dm-stats.c [234:391]

• 132 lines of code
• 25 McCabe index (conditional complexity)

static int dm_stats_create(struct dm_stats *stats, sector_t start, sector_t end,
			   sector_t step, unsigned stat_flags,
			   unsigned n_histogram_entries,
			   unsigned long long *histogram_boundaries,
			   const char *program_id, const char *aux_data,
			   void (*suspend_callback)(struct mapped_device *),
			   void (*resume_callback)(struct mapped_device *),
			   struct mapped_device *md)
{
	struct list_head *l;
	struct dm_stat *s, *tmp_s;
	sector_t n_entries;
	size_t ni;
	size_t shared_alloc_size;
	size_t percpu_alloc_size;
	size_t histogram_alloc_size;
	struct dm_stat_percpu *p;
	int cpu;
	int ret_id;
	int r;

	if (end < start || !step)
		return -EINVAL;

	n_entries = end - start;
	if (dm_sector_div64(n_entries, step))
		n_entries++;

	if (n_entries != (size_t)n_entries || !(size_t)(n_entries + 1))
		return -EOVERFLOW;

	shared_alloc_size = struct_size(s, stat_shared, n_entries);
	if ((shared_alloc_size - sizeof(struct dm_stat)) / sizeof(struct dm_stat_shared) != n_entries)
		return -EOVERFLOW;

	percpu_alloc_size = (size_t)n_entries * sizeof(struct dm_stat_percpu);
	if (percpu_alloc_size / sizeof(struct dm_stat_percpu) != n_entries)
		return -EOVERFLOW;

	histogram_alloc_size = (n_histogram_entries + 1) * (size_t)n_entries * sizeof(unsigned long long);
	if (histogram_alloc_size / (n_histogram_entries + 1) != (size_t)n_entries * sizeof(unsigned long long))
		return -EOVERFLOW;

	if (!check_shared_memory(shared_alloc_size + histogram_alloc_size +
				 num_possible_cpus() * (percpu_alloc_size + histogram_alloc_size)))
		return -ENOMEM;

	s = dm_kvzalloc(shared_alloc_size, NUMA_NO_NODE);
	if (!s)
		return -ENOMEM;

	s->stat_flags = stat_flags;
	s->n_entries = n_entries;
	s->start = start;
	s->end = end;
	s->step = step;
	s->shared_alloc_size = shared_alloc_size;
	s->percpu_alloc_size = percpu_alloc_size;
	s->histogram_alloc_size = histogram_alloc_size;

	s->n_histogram_entries = n_histogram_entries;
	s->histogram_boundaries = kmemdup(histogram_boundaries,
					  s->n_histogram_entries * sizeof(unsigned long long), GFP_KERNEL);
	if (!s->histogram_boundaries) {
		r = -ENOMEM;
		goto out;
	}

	s->program_id = kstrdup(program_id, GFP_KERNEL);
	if (!s->program_id) {
		r = -ENOMEM;
		goto out;
	}
	s->aux_data = kstrdup(aux_data, GFP_KERNEL);
	if (!s->aux_data) {
		r = -ENOMEM;
		goto out;
	}

	for (ni = 0; ni < n_entries; ni++) {
		atomic_set(&s->stat_shared[ni].in_flight[READ], 0);
		atomic_set(&s->stat_shared[ni].in_flight[WRITE], 0);
	}

	if (s->n_histogram_entries) {
		unsigned long long *hi;
		hi = dm_kvzalloc(s->histogram_alloc_size, NUMA_NO_NODE);
		if (!hi) {
			r = -ENOMEM;
			goto out;
		}
		for (ni = 0; ni < n_entries; ni++) {
			s->stat_shared[ni].tmp.histogram = hi;
			hi += s->n_histogram_entries + 1;
		}
	}

	for_each_possible_cpu(cpu) {
		p = dm_kvzalloc(percpu_alloc_size, cpu_to_node(cpu));
		if (!p) {
			r = -ENOMEM;
			goto out;
		}
		s->stat_percpu[cpu] = p;
		if (s->n_histogram_entries) {
			unsigned long long *hi;
			hi = dm_kvzalloc(s->histogram_alloc_size, cpu_to_node(cpu));
			if (!hi) {
				r = -ENOMEM;
				goto out;
			}
			for (ni = 0; ni < n_entries; ni++) {
				p[ni].histogram = hi;
				hi += s->n_histogram_entries + 1;
			}
		}
	}

	/*
	 * Suspend/resume to make sure there is no i/o in flight,
	 * so that newly created statistics will be exact.
	 *
	 * (note: we couldn't suspend earlier because we must not
	 * allocate memory while suspended)
	 */
	suspend_callback(md);

	mutex_lock(&stats->mutex);
	s->id = 0;
	list_for_each(l, &stats->list) {
		tmp_s = container_of(l, struct dm_stat, list_entry);
		if (WARN_ON(tmp_s->id < s->id)) {
			r = -EINVAL;
			goto out_unlock_resume;
		}
		if (tmp_s->id > s->id)
			break;
		if (unlikely(s->id == INT_MAX)) {
			r = -ENFILE;
			goto out_unlock_resume;
		}
		s->id++;
	}
	ret_id = s->id;
	list_add_tail_rcu(&s->list_entry, l);
	mutex_unlock(&stats->mutex);

	resume_callback(md);

	return ret_id;

out_unlock_resume:
	mutex_unlock(&stats->mutex);
	resume_callback(md);
out:
	dm_stat_free(&s->rcu_head);
	return r;
}