Re: [PATCH bpf-next v4 1/5] bpf: Introduce task_file open-coded iterator kfuncs

[Jiri Olsa <olsajiri@gmail.com>]

On Tue, Nov 19, 2024 at 05:53:58PM +0000, Juntong Deng wrote:

SNIP

> +/**
> + * bpf_iter_task_file_next() - Get the next file in bpf_iter_task_file
> + *
> + * bpf_iter_task_file_next acquires a reference to the struct file.
> + *
> + * The reference to struct file acquired by the previous
> + * bpf_iter_task_file_next() is released in the next bpf_iter_task_file_next(),
> + * and the last reference is released in the last bpf_iter_task_file_next()
> + * that returns NULL.
> + *
> + * @it: the bpf_iter_task_file to be checked
> + *
> + * @returns a pointer to bpf_iter_task_file_item
> + */
> +__bpf_kfunc struct bpf_iter_task_file_item *bpf_iter_task_file_next(struct bpf_iter_task_file *it)
> +{
> +	struct bpf_iter_task_file_kern *kit = (void *)it;
> +	struct bpf_iter_task_file_item *item = &kit->item;
> +
> +	if (item->file)
> +		fput(item->file);
> +

missing rcu_read_lock ?

jirka

> +	item->file = task_lookup_next_fdget_rcu(item->task, &kit->next_fd);
> +	item->fd = kit->next_fd;
> +
> +	kit->next_fd++;
> +
> +	if (!item->file)
> +		return NULL;
> +
> +	return item;
> +}
> +
> +/**
> + * bpf_iter_task_file_destroy() - Destroy a bpf_iter_task_file
> + *
> + * If the iterator does not iterate to the end, then the last
> + * struct file reference is released at this time.
> + *
> + * @it: the bpf_iter_task_file to be destroyed
> + */
> +__bpf_kfunc void bpf_iter_task_file_destroy(struct bpf_iter_task_file *it)
> +{
> +	struct bpf_iter_task_file_kern *kit = (void *)it;
> +	struct bpf_iter_task_file_item *item = &kit->item;
> +
> +	if (item->file)
> +		fput(item->file);
> +}
> +
>  __bpf_kfunc_end_defs();
>  
>  DEFINE_PER_CPU(struct mmap_unlock_irq_work, mmap_unlock_work);
> -- 
> 2.39.5
>