Re: Why I want PTRACE_O_TRACESTOP option

[Denys Vlasenko]

On Friday 09 September 2011 02:18, Tejun Heo wrote:
> Hello, Denys.
> 
> On Thu, Sep 08, 2011 at 06:50:01PM +0200, Denys Vlasenko wrote:
> > Consider what will happen when a next ptrace fix will require
> > a way to change ptrace API at runtime. A new option will likely
> > be introduced, say, PTRACE_O_TRACEPONY, with next available
> > bit position 7, and perhaps some new event will be generated,
> > PTRACE_EVENT_PONY, with value.... yes, it can't be 7,
> > PTRACE_EVENT_STOP took it. So it will probably be 8.
> 
> Then, just give it the next matching number.

My point is that previously, ptrace behavior was modified by setting
options. Why don't we use this mechanism? Why we invent a different
wheel? Ptrace is ugly as-is, why complicate it even further?

The argument was that SETOPTIONS wasn't suitable for modifying
attach behavior, but this is fixed by "set options on SEIZE"
patch. I don't see why we can't use options mechanist to affect
group-stop behavior now.

-- 
vda
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