Re: [PATCH RESEND v2 22/26] ALSA: info: let procfs own the seq_file of text entries

[Jann Horn]

On Wed, Nov 4, 2026 at 8:47 PM Christian Brauner <brauner@xxxxxxxxxx> wrote:
> Declare the show function and let procfs open and free the seq_file.
> ->proc_open() only sets up the private data and preallocates the buffer
> now and ->proc_release() no longer releases the seq_file. Reading an
> entry then no longer holds up its removal when the card goes away.
[...]
> +                       goto error;
> +       }
> +       m->private = data;
>         return 0;
>
>   error:
> @@ -387,7 +388,6 @@ static int snd_info_text_entry_release(struct inode *inode, struct file *file)
>         if (data->wbuffer && entry->c.text.write)
>                 entry->c.text.write(entry, data->wbuffer);
>
> -       single_release(inode, file);
>         kfree(data->rbuffer);
>         if (data->wbuffer) {
>                 kvfree(data->wbuffer->buffer);
> @@ -401,11 +401,10 @@ static int snd_info_text_entry_release(struct inode *inode, struct file *file)
>
>  static const struct proc_ops snd_info_text_entry_ops =
>  {
> +       .proc_show      = snd_info_seq_show,
>         .proc_open      = snd_info_text_entry_open,
>         .proc_release   = snd_info_text_entry_release,
>         .proc_write     = snd_info_text_entry_write,
> -       .proc_lseek     = seq_lseek,
> -       .proc_read      = seq_read,
>  };

Is this safe? Looking at the work.procfs.cleanup tree, the
proc_release handler (snd_info_text_entry_release()) can call
`entry->c.text.write(entry, data->wbuffer)`, and the only kind of
reference dropped by snd_info_text_entry_release() is a module
reference.

I think the entry could concurrently get freed by snd_info_free_entry()?