Re: [PATCH] fs: proc: fix error return code of proc_map_files_readdir()

Jia-Ju Bai
2021-03-10T01:12:49Z

On 2021/3/10 3:05, Alexey Dobriyan wrote:
> On Tue, Mar 09, 2021 at 10:30:23AM -0800, Eric Biggers wrote:
>
>>> --- a/fs/proc/base.c
>>> +++ b/fs/proc/base.c
>>> @@ -2332,8 +2332,10 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx)
>>> goto out_put_task;
>>>
>>> mm = get_task_mm(task);
>>> - if (!mm)
>>> + if (!mm) {
>>> + ret = -ENOENT;
>>> goto out_put_task;
>>> + }
>>>
>>> ret = mmap_read_lock_killable(mm);
>> Is there something in particular that makes you think that returning ENOENT is
>> the correct behavior in this case? Try 'ls /proc/$pid/map_files' where pid is a
>> kernel thread; it's an empty directory, which is probably intentional. Your
>> patch would change reading the directory to fail with ENOENT.
> Yes. 0 from readdir means "no more stuff", not an error.

Thanks for your reply and explanation.
I am sorry for the false report...

Best wishes,
Jia-Ju Bai