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From: Thomas Gleixner <tglx@linutronix.de>
To: Oleg Nesterov <oleg@redhat.com>, Jens Axboe <axboe@kernel.dk>
Cc: linux-kernel@vger.kernel.org, io-uring@vger.kernel.org,
	peterz@infradead.org
Subject: Re: [PATCH 3/3] task_work: use TIF_TASKWORK if available
Date: Fri, 02 Oct 2020 17:31:07 +0200	[thread overview]
Message-ID: <871rigejb8.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20201002151415.GA29066@redhat.com>

On Fri, Oct 02 2020 at 17:14, Oleg Nesterov wrote:
> Heh. To be honest I don't really like 1-2 ;)

I do not like any of this :)

> So I think that if we are going to add TIF_TASKWORK we should generalize
> this logic and turn it into TIF_NOTIFY_SIGNAL. Similar to TIF_NOTIFY_RESUME
> but implies signal_pending().
>
> IOW, something like
>
> 	void set_notify_signal(task)
> 	{
> 		if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_SIGNAL)) {
> 			if (!wake_up_state(task, TASK_INTERRUPTIBLE))
> 				kick_process(t);
> 		}
> 	}
>
> 	// called by exit_to_user_mode_loop() if ti_work & _TIF_NOTIFY_SIGNAL
> 	void tracehook_notify_signal(regs)
> 	{
> 		clear_thread_flag(TIF_NOTIFY_SIGNAL);
> 		smp_mb__after_atomic();
> 		if (unlikely(current->task_works))
> 			task_work_run();
> 	}
>
> This way task_work_run() doesn't need to clear TIF_NOTIFY_SIGNAL and it can
> have more users.

I think it's fundamentaly wrong that we have several places and several
flags which handle task_work_run() instead of having exactly one place
and one flag.

Thanks,

        tglx


  reply	other threads:[~2020-10-02 15:31 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-01 19:42 [PATCHSET RFC 0/3] kernel: decouple TASK_WORK TWA_SIGNAL handling from signals Jens Axboe
2020-10-01 19:42 ` [PATCH 1/3] kernel: add task_sigpending() helper Jens Axboe
2020-10-01 19:42 ` [PATCH 2/3] kernel: decouple TASK_WORK TWA_SIGNAL handling from signals Jens Axboe
2020-10-01 19:42 ` [PATCH 3/3] task_work: use TIF_TASKWORK if available Jens Axboe
2020-10-02 15:14   ` Oleg Nesterov
2020-10-02 15:31     ` Thomas Gleixner [this message]
2020-10-02 15:38       ` Oleg Nesterov
2020-10-02 16:18         ` Jens Axboe
2020-10-03  1:49         ` Thomas Gleixner
2020-10-03 15:35           ` Jens Axboe
2020-10-02 15:52       ` Jens Axboe
2020-10-02 16:42         ` Jens Axboe
2020-10-02 19:10         ` Thomas Gleixner
2020-10-02 20:14           ` Jens Axboe
2020-10-02 15:53     ` Jens Axboe

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