Re: [PATCH 11/17] ptrace: implement PTRACE_SEIZE

[Tejun Heo]

Hey,

On Wed, Jun 01, 2011 at 09:01:17PM +0200, Oleg Nesterov wrote:
> On 05/30, Tejun Heo wrote:
> > implements a new ptrace request PTRACE_SEIZE which attaches and traps
> > tracee
> 
> it doesn't trap the tracee ;)

Ah, missed that one.  Will update.

> > * PTRACE_SEIZE, unlike ATTACH, doesn't force tracee to trap.  After
> >   attaching tracee continues to run unless a trap condition occurs.
> 
> OK.
> 
> Just to remind, tracehook_report_clone() shouldn't send SIGSTOP if
> the auto-attached tracee is PT_SEIZED.

Yeap, let's deal with it (and others) later.

> > * If PTRACE_SEIZE'd, group stop uses PTRACE_EVENT_STOP trap which uses
> >   exit_code of (SIGTRAP | PTRACE_EVENT_STOP << 8) instead of the
> >   stopping signal number
> 
> Hmm. May be it would be better to report stopping_signal | PTRACE_EVENT_STOP
> instead... I am not sure yet, but it seems this way we can avoid the
> PTRACE_GETSIGINFO changes. I'll try to explain later, when I finsh the
> reading.

Maybe, unsure.  Currently all the existing PTRACE_EVENT_* codes use
SIGTRAP and requiring GETSIGINFO on TRAP_STOP seems reasonable enough.
So, (stopping signo) | EVENT_STOP on stops, SIGTRAP | EVENT_STOP on
INTERRUPT and SIGCONT | EVENT_STOP (hmm....) on continued?

Thanks.

-- 
tejun
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