Re: [PATCH 03/10] ptrace: implement PTRACE_SEIZE

[Denys Vlasenko]

On Thursday 19 May 2011 21:31, Pedro Alves wrote:
> On Thursday 19 May 2011 15:17:28, Tejun Heo wrote:
> > But making SEIZE not trigger INTERRUPT and SETOPTIONS without
> > requiring TRACED don't seem too difficult.  Jan, would that be enough?
> > Oleg, what do you think?
> 
> UUIC, that opens a race where between SEIZEing and
> SETOPTIONS(O_TRACE FORK|VFORK|EXEC...), the tracee can
> fork/vfork/clone/exec, without the tracer getting the
> nice corresponding PTRACE_EVENT_ events.

SEIZE,fork-in-tracee,INTERRUPT sequence is indistinguishable
from SEIZE happening two microseconds later:

fork-in-tracee,SEIZE,INTERRUPT

> In GDBs case, GDB will want to poke at memory
> right after attaching

...where "right after attaching" is defined as "when the first ptrace-stop
is reported". Which will happen very soon.

-- 
vda
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