Hi Andrzej,
[...]
> -void ref_tracker_dir_print_locked(struct ref_tracker_dir *dir,
> - unsigned int display_limit)
> +struct ref_tracker_dir_stats {
> + int total;
> + int count;
> + struct {
> + depot_stack_handle_t stack_handle;
> + unsigned int count;
> + } stacks[];
> +};
> +
> +static struct ref_tracker_dir_stats *
> +ref_tracker_get_stats(struct ref_tracker_dir *dir, unsigned int limit)
> {
> + struct ref_tracker_dir_stats *stats;
> struct ref_tracker *tracker;
> - unsigned int i = 0;
>
> - lockdep_assert_held(&dir->lock);
> + stats = kmalloc(struct_size(stats, stacks, limit),
> + GFP_NOWAIT | __GFP_NOWARN);
> + if (!stats)
> + return ERR_PTR(-ENOMEM);
> + stats->total = 0;
> + stats->count = 0;
>
> list_for_each_entry(tracker, &dir->list, head) {
> - if (i < display_limit) {
> - pr_err("leaked reference.\n");
> - if (tracker->alloc_stack_handle)
> - stack_depot_print(tracker->alloc_stack_handle);
> - i++;
> - } else {
> - break;
> + depot_stack_handle_t stack = tracker->alloc_stack_handle;
> + int i;
> +
> + ++stats->total;
> + for (i = 0; i < stats->count; ++i)
> + if (stats->stacks[i].stack_handle == stack)
> + break;
> + if (i >= limit)
> + continue;
> + if (i >= stats->count) {
> + stats->stacks[i].stack_handle = stack;
> + stats->stacks[i].count = 0;
> + ++stats->count;
> }
> + ++stats->stacks[i].count;
> + }
> +
> + return stats;
> +}
> +
> +void ref_tracker_dir_print_locked(struct ref_tracker_dir *dir,
> + unsigned int display_limit)
> +{
> + struct ref_tracker_dir_stats *stats;
> + unsigned int i = 0, skipped;
> + depot_stack_handle_t stack;
> + char *sbuf;
> +
> + lockdep_assert_held(&dir->lock);
> +
> + if (list_empty(&dir->list))
> + return;
> +
> + stats = ref_tracker_get_stats(dir, display_limit);
> + if (IS_ERR(stats)) {
> + pr_err("%s@%pK: couldn't get stats, error %pe\n",
> + dir->name, dir, stats);
> + return;
> }
> +
> + sbuf = kmalloc(STACK_BUF_SIZE, GFP_NOWAIT | __GFP_NOWARN);
> +
> + for (i = 0, skipped = stats->total; i < stats->count; ++i) {
> + stack = stats->stacks[i].stack_handle;
> + if (sbuf && !stack_depot_snprint(stack, sbuf, STACK_BUF_SIZE, 4))
> + sbuf[0] = 0;
> + pr_err("%s@%pK has %d/%d users at\n%s\n", dir->name, dir,
> + stats->stacks[i].count, stats->total, sbuf);
> + skipped -= stats->stacks[i].count;
> + }
> +
> + if (skipped)
> + pr_err("%s@%pK skipped reports about %d/%d users.\n",
> + dir->name, dir, skipped, stats->total);
> +
> + kfree(sbuf);
> +
> + kfree(stats);
There's a chance of confusion here because
ref_tracker_get_stats() might need a ref_tracker_put_stats() to
go with it.
When you allocate in one function and free in another without a
clear pair (get/put, alloc/free, etc.), it can be hard to notice
and could lead to mistakes.
But in this simple situation, it's not a big problem, and I'm not
sure if having the put side is really needed.
Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>
Thanks,
Andi
> }
> EXPORT_SYMBOL(ref_tracker_dir_print_locked);
>
>
> --
> 2.34.1
