Re: [patch] O(1) sys_exit(), threading, scalable-exit-2.5.31-A6

From: Linus Torvalds (
Date: Mon Aug 19 2002 - 12:42:06 EST

Hmm.. This looks good, but I wonder if the real problem isn't really that
our ptrace approach has always been kind of flaky.

Basically, we started with the notion that only parents can trace their
children, so no reparenting was ever needed. Then PTRACE_ATTACH came
along, and we did the reparenting, and I think _that_ is where we made our
big mistake.

We sh ould just have made a separate "tsk->tracer" pointer, instead of
continuing with the perverted "my parent is my tracer" logic. We shouldn't
really re-write the parent/child relationship just because we're being

I'd be happy to apply this patch (well, your fixed version), but I think
I'd prefer even more to make the whole reparenting go away, and keep the
child list valid all through the lifetime of a process. How painful could
that be?


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