Re: [PATCH 04/10] ptrace: implement PTRACE_INTERRUPT

From: Tejun Heo
Date: Thu May 19 2011 - 08:07:32 EST


Hello,

On Wed, May 18, 2011 at 08:38:15PM +0200, Oleg Nesterov wrote:
> On 05/16, Tejun Heo wrote:
> >
> > + case PTRACE_INTERRUPT:
> > + /*
> > + * Stop tracee without any side-effect on signal or job
> > + * control. At least one trap is guaranteed to happen
> > + * after this request. If @child is already trapped, the
> > + * current trap is not disturbed and another trap will
> > + * happen after the current trap is ended with PTRACE_CONT.
> > + *
> > + * The actual trap might not be PTRACE_EVENT_STOP trap but
> > + * the pending condition is cleared regardless.
> > + */
> > + if (likely(child->ptrace & PT_SEIZED) &&
> > + lock_task_sighand(child, &flags)) {
> > + child->jobctl |= JOBCTL_TRAP_STOP;
>
> The same race with do_signal_stop() afaics.

I didn't understand that one, so you'll need to elaborate.

> Otherwise looks fine to me. Compared to V1, personally I like the new
> behaviour more. PTRACE_INTERRUPT and PTRACE_SEIZE do the same.

Great. :)

Thanks.

--
tejun
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