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

[Jia-Ju Bai]

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