Re: Why I want PTRACE_O_TRACESTOP option

[Tejun Heo <tj@kernel.org>]

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.

If options naturally happen to match the events, that's a nice
coincidence.  If the real life requirement deviates from the beautiful
one-to-one mapping, then, so be it.  No, the magical contiguous one to
one mapping isn't the most important design concern.

To me, the rationale presented here almost argues against
PTRACE_O_TRACESTOP.  :(

Thanks.

-- 
tejun