Re: More waitpid issues with CLONE_DETACHED/CLONE_THREAD

[Andries Brouwer <aebr _at_ xxxxxxxxxx>]

On Sun, Feb 01, 2004 at 04:55:11PM -0800, Linus Torvalds wrote:

> On Sun, 1 Feb 2004, Roland McGrath wrote:

> > I haven't really looked into the problem with Dan's test case yet (didn't
> > seem to reproduce, but I haven't tried a current and cruft-free kernel yet).  
> > But I don't see any problem with the implementation of PTRACE_KILL.
> 
> Hmm.. For me, Dan's program (with "-DBUG -DNOTHREAD") results in a 
> sleeping parent, and both children are likewise just sleeping. Despite the 
> fact that the parent just did the PTRACE_KILL on child2.
> 
> I didn't trace it through the kernel, it just looked like PTRACE_KILL 
> didn't do anything.

I agree with both of you.

So, I think what happens is that PTRACE_KILL immediately after the PTRACE_CONT
works because there is no schedule in between, so the effect of PTRACE_KILL
is still seen by the (grand)child.
Once the grandchild has returned it has become immune for PTRACE_KILL.
Maybe there is no bug.

Andries
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