Re: [PATCH] autofs: fix the wrong usage of the deprecated task_pgrp_nr()

Oleg Nesterov
2009-01-19T21:34:16Z

On 01/19, Serge E. Hallyn wrote:
>
> Quoting Oleg Nesterov (oleg@redhat.com):
> >
> > This is the next patch. This one does
> >
> > --- CUR/fs/autofs/inode.c~1_AUTOFS 2009-01-12 23:07:46.000000000 +0100
> > +++ CUR/fs/autofs/inode.c 2009-01-18 06:18:49.000000000 +0100
> > @@ -78,7 +78,7 @@ static int parse_options(char *options,
> >
> > *uid = current_uid();
> > *gid = current_gid();
> > - *pgrp = task_pgrp_nr(current);
> > + *pgrp = task_pgrp_vnr(current);
>
> Ok, that was the one I had looked at earlier (though now I can't find
> it). But that just seems wrong to me. We should certainly not be
> caching a pid_vnr in the kernel. That is imo incomparably worse than
> storing a pid_nr.

We do not cache it. We use this pgrp as an argument for find_pid()
right after return from parse_options(). And find_pid() uses
current->nsproxy->pid_ns. That is why this is bugfix.

> Can we just jump straight to caching the struct pid?

Of course it is ugly to store pid_t and then call find_pid(),
I don't understand why the code was written this way. But I
am not going to cleanup this code ;)

(note also that the 2nd patch I sent for autofs4 does not use
pid_t at all).

> > passing pid_t's in from userspace uses current namespace, with
> > or without the patch.
>
> Which makes sense on the one hand, but OTOH could be confusing
> if as I requested we print out init_pid_ns values. (sigh)

But it is not possible to pass the global pid_t from within
the subnamespace via "pgrp=" option, automount (or whatever)
just can't know it when it runs in the subnamespace.

> Yes... would it be overkill to just print both?

perharps, I don't know...

But this is imho a bit off-topic, we can change the debugging
output later any way we like.

Oleg.