Re: [PATCHSET RFC v3 0/6] Add support for TIF_NOTIFY_SIGNAL

Jens Axboe
2020-10-09T15:21:30Z

On 10/9/20 2:01 AM, Miroslav Benes wrote:
> On Thu, 8 Oct 2020, Oleg Nesterov wrote:
>
>> On 10/05, Jens Axboe wrote:
>>>
>>> Hi,
>>>
>>> The goal is this patch series is to decouple TWA_SIGNAL based task_work
>>> from real signals and signal delivery.
>>
>> I think TIF_NOTIFY_SIGNAL can have more users. Say, we can move
>> try_to_freeze() from get_signal() to tracehook_notify_signal(), kill
>> fake_signal_wake_up(), and remove freezing() from recalc_sigpending().
>>
>> Probably the same for TIF_PATCH_PENDING, klp_send_signals() can use
>> set_notify_signal() rather than signal_wake_up().
>
> Yes, that was my impression from the patch set too, when I accidentally
> noticed it.
>
> Jens, could you CC our live patching ML when you submit v4, please? It
> would be a nice cleanup.

Definitely, though it'd be v5 at this point. But we really need to get
all archs supporting TIF_NOTIFY_SIGNAL first. Once we have that, there's
a whole slew of cleanups that'll fall out naturally:

- Removal of JOBCTL_TASK_WORK
- Removal of special path for TWA_SIGNAL in task_work
- TIF_PATCH_PENDING can be converted and then removed
- try_to_freeze() cleanup that Oleg mentioned

And probably more I'm not thinking of right now :-)

--
Jens Axboe