Re: [PATCH v8 06/14] task_isolation: provide strict mode configurable signal

Andy Lutomirski
2015-10-21T01:43:15Z

On Tue, Oct 20, 2015 at 6:30 PM, Chris Metcalf <cmetcalf@ezchip.com> wrote:
> On 10/20/2015 8:56 PM, Steven Rostedt wrote:
>>
>> On Tue, 20 Oct 2015 16:36:04 -0400
>> Chris Metcalf <cmetcalf@ezchip.com> wrote:
>>
>>> Allow userspace to override the default SIGKILL delivered
>>> when a task_isolation process in STRICT mode does a syscall
>>> or otherwise synchronously enters the kernel.
>>>
>> Is this really a good idea? This means that there's no way to terminate
>> a task in this mode, even if it goes astray.
>
>
> It doesn't map SIGKILL to some other signal unconditionally. It just allows
> the "hey, you broke the STRICT contract and entered the kernel" signal
> to be something besides the default SIGKILL.
>

...which has the odd side effect that sending a non-fatal signal from
another process will cause the strict process to enter the kernel and
receive an extra signal.

I still dislike this thing. It seems like a debugging feature being
implemented using signals instead of existing APIs. I *still* don't
see why perf can't be used to accomplish your goal.

--Andy