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

[Eric W. Biederman]

Cyrill Gorcunov <gorcunov at gmail.com> writes:

> 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?

That is present in files_lookup_fd_rcu, so this code should
be good from the warning side.

Eric