Re: [PATCH] ptrace: make former thread ID available viaPTRACE_GETEVENTMSG after PTRACE_EVENT_EXEC stop (v.2)
From: Tejun Heo
Date: Tue Jun 28 2011 - 08:43:31 EST
Hello,
On Tue, Jun 28, 2011 at 02:30:36PM +0200, Denys Vlasenko wrote:
> On Tue, Jun 28, 2011 at 10:25 AM, Tejun Heo <tj@xxxxxxxxxx> wrote:
> > On Mon, Jun 27, 2011 at 05:18:27PM +0200, Oleg Nesterov wrote:
> > Yeah, but that's a pretty silly way to do it. If we make it depend on
> > PT_SEIZED, we can simply say "if seized, EXEC reports..." but as it
> > currently stands, it would go like "If the message is non-zero on
> > EXEC, it indicates... This behavior is valid since kernel version
> > x.x.x".
>
> This is true for any new addition to API.
> It starts from some kernel version.
Hmmm... but as I wrote above, we have a choice to make here and the
two options are clearly different?
> > Maybe adding a guarantee that PTRACE_SEIZE capable kernel
> > always reports the old pid on EXEC but that would still seem
> > unnecessarily complicated. It isn't a bug fix. I don't see much
> > point in introducing new behavior separately.
>
> This new feature looks orthogonal to PTRACE_SEIZE to me.
Yeah, sure, but we're bundling a number of behavior changes with
PT_SEIZED because it's impractical to introduce each with its own
compatibility / feature test bits, so it makes sense to do the same
with this one, I think. It's not like there's a lot to gain by
supporting this outside of SEIZE anyway.
Thanks.
--
tejun
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