Re: More waitpid issues with CLONE_DETACHED/CLONE_THREAD

[Linus Torvalds]

On Mon, 2 Feb 2004, Andries Brouwer wrote:
> 
> 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.

Well, Duh! You'r eobviously right.

PTRACE_KILL is a special case, since it's supposed to work _regardless_ of 
whether the process being traced is actually stopped for tracing or not.

And Roland is correct that PTRACE_KILL works fine _if_ it is stopped. 

But for the case where it isn't (and Daniel's program isn't, since it did 
the PTRACE_CONT), PTRACE_KILL does nothing.

> Maybe there is no bug.

No, I do believe that PTRACE_KILL is supposed to kill the child even if it 
wasn't synchronized. See the special case for "ptrace_check_attach()", 
which allows a PTRACE_KILL to happen even for a nonsynchronized target.

		Linus
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