Re: [PATCH v2 11/24] file: Implement task_lookup_fd_rcu

[Cyrill Gorcunov]

On Fri, Nov 20, 2020 at 05:14:28PM -0600, Eric W. Biederman wrote:
> 
> diff --git a/fs/file.c b/fs/file.c
> index 5861c4f89419..6448523ca29e 100644
> --- a/fs/file.c
> +++ b/fs/file.c
> @@ -865,6 +865,21 @@ struct file *fget_task(struct task_struct *task, unsigned int fd)
>  	return file;
>  }
>  
> +struct file *task_lookup_fd_rcu(struct task_struct *task, unsigned int fd)
> +{
> +	/* Must be called with rcu_read_lock held */

Eric, maybe worth to have something like

	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
			 "suspicious task_lookup_fd_rcu() usage");

here?