[lkml]   [2002]   [Sep]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [patch] ptrace-fix-2.5.33-A1
On Fri, Sep 06, 2002 at 12:25:32AM +0200, Ingo Molnar wrote:
> On Thu, 5 Sep 2002, Daniel Jacobowitz wrote:
> > Right - let me rephrase. Tasks which are either:
> > - untraced, normal
> > - traced, but traced _by their parent_
> > are on the sibling/children list.
> hm, why the distinction along whether the debugger == real parent? What
> wrong can happen if we always move traced tasks to the ptrace list? The
> task will be both in the ptrace list and in the parent's child list, and
> everything should work as expected. This looks a more symmetric and
> simpler thing to me.

Hmm, I like that idea. But I was talking about current implementation.
If we want to do this then we'd need to fix up every ptrace
implementation in every architecture to call the appropriate function;
it's a separate problem.

> > > this splitup of the lists makes it possible for the debugger to do a wait4
> > > that will get events from the debugged task, and for the debugged task to
> > > also be available to the real parent.
> >
> > Great. I'm not exactly sure on how this works right now: sys_wait4 only
> > iterates over ->children, with the exception of the special code in
> > TASK_ZOMBIE. I'm not quite sure when events from a traced process get
> > to the normal parent of that process, or when they're supposed to.
> i'm not sure about this either. What happens if an (untraced) parent has
> traced and untraced children, and does a wait4. Would it confuse the
> debugger if the parent could get one of the traced tasks as a result in
> wait4? And how does the debugger solve this problem?

Well, it seems to me that when a traced task has an event, it should be
reported first to the debugger - for signals this happens in do_signal
- and then possibly to the normal parent. But I'm not sure if this
actually happens right now or not. Worth investigating some more.

Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:28    [W:0.058 / U:0.468 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site