Re: [PATCH] Fix for ptrace breakage

[OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>]

Daniel Jacobowitz <dan@debian.org> writes:

> > > We have the tasklist lock.  How can there be a race here?  The parent
> > > can't detach while we're holding the tasklist lock.  If there is a race
> > > with PTRACE_SETOPTIONS, then PTRACE_SETOPTIONS should take the lock.
> > 
> > No. If the real parent don't change ->ptrace, it doesn't need
> > lock.
> 
> I don't understand what you mean by that.  Do you mean, "if it does
> change ->ptrace, it doesn't need a lock"?

Basically, only tracer can change ->ptrace of traced child. And, it
doesn't need lock. (there are some exceptions)

> > Ah, ok. I think, it's longtime (odd) behavior. And you think, it's
> > a bug. Right?
> > 
> > And, both of your and old code has odd behavior. yes?
> 
> Before your patch, do_notify_parent didn't get called; I think that
> perhaps it should be.  I'll think about that.  After your patch the
> process group will be unexpectedly orphaned, which is not now the case.
> 
> Let me sit on this for a couple of hours.  I'll send you an alternative
> patch to look at.

Ok. But I'll sleep soon. So, I'll look it, after having come back from
the office.
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>