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From: Oleg Nesterov <oleg@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-kernel@vger.kernel.org, io-uring@vger.kernel.org,
	peterz@infradead.org, tglx@linutronix.de
Subject: Re: [PATCH 3/5] kernel: add support for TIF_NOTIFY_SIGNAL
Date: Thu, 15 Oct 2020 16:47:14 +0200	[thread overview]
Message-ID: <20201015144713.GJ24156@redhat.com> (raw)
In-Reply-To: <788b31b7-6acc-cc85-5e91-d0c2538341b7@kernel.dk>

On 10/15, Jens Axboe wrote:
>
> On 10/15/20 8:37 AM, Oleg Nesterov wrote:
> > On 10/15, Jens Axboe wrote:
> >>
> >> On 10/15/20 8:31 AM, Oleg Nesterov wrote:
> >>> On 10/15, Jens Axboe wrote:
> >>>>
> >>>>  static inline int signal_pending(struct task_struct *p)
> >>>>  {
> >>>> +#if defined(CONFIG_GENERIC_ENTRY) && defined(TIF_NOTIFY_SIGNAL)
> >>>> +	/*
> >>>> +	 * TIF_NOTIFY_SIGNAL isn't really a signal, but it requires the same
> >>>> +	 * behavior in terms of ensuring that we break out of wait loops
> >>>> +	 * so that notify signal callbacks can be processed.
> >>>> +	 */
> >>>> +	if (unlikely(test_tsk_thread_flag(p, TIF_NOTIFY_SIGNAL)))
> >>>> +		return 1;
> >>>> +#endif
> >>>>  	return task_sigpending(p);
> >>>>  }
> >>>
> >>> I don't understand why does this version requires CONFIG_GENERIC_ENTRY.
> >>>
> >>> Afaics, it is very easy to change all the non-x86 arches to support
> >>> TIF_NOTIFY_SIGNAL, but it is not trivial to change them all to use
> >>> kernel/entry/common.c ?
> >>
> >> I think that Thomas wants to gate TIF_NOTIFY_SIGNAL on conversion to
> >> the generic entry code?
> > 
> > Then I think TIF_NOTIFY_SIGNAL will be never fully supported ;)
> 
> That is indeed a worry. From a functionality point of view, with the
> major archs supporting it, I'm not too worried about that side. But it
> does mean that we'll be stuck with the ifdeffery forever, which isn't
> great.

plus we can't kill the ugly JOBCTL_TASK_WORK.

Oleg.


  reply	other threads:[~2020-10-15 14:47 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-15 13:16 [PATCHSET v5] Add support for TIF_NOTIFY_SIGNAL Jens Axboe
2020-10-15 13:16 ` [PATCH 1/5] tracehook: clear TIF_NOTIFY_RESUME in tracehook_notify_resume() Jens Axboe
2020-10-15 14:42   ` Oleg Nesterov
2020-10-15 14:43     ` Jens Axboe
2020-10-15 13:16 ` [PATCH 2/5] kernel: add task_sigpending() helper Jens Axboe
2020-10-15 14:42   ` Oleg Nesterov
2020-10-15 13:16 ` [PATCH 3/5] kernel: add support for TIF_NOTIFY_SIGNAL Jens Axboe
2020-10-15 14:31   ` Oleg Nesterov
2020-10-15 14:33     ` Jens Axboe
2020-10-15 14:37       ` Oleg Nesterov
2020-10-15 14:43         ` Jens Axboe
2020-10-15 14:47           ` Oleg Nesterov [this message]
2020-10-15 14:53             ` Oleg Nesterov
2020-10-15 14:56               ` Jens Axboe
2020-10-15 15:01         ` Thomas Gleixner
2020-10-15 15:27           ` Oleg Nesterov
2020-10-15 14:44   ` Oleg Nesterov
2020-10-15 13:17 ` [PATCH 4/5] x86: wire up TIF_NOTIFY_SIGNAL Jens Axboe
2020-10-15 14:11   ` Thomas Gleixner
2020-10-15 14:31     ` Jens Axboe
2020-10-15 14:34       ` Thomas Gleixner
2020-10-15 14:35         ` Jens Axboe
2020-10-15 14:36       ` Oleg Nesterov
2020-10-15 14:42         ` Jens Axboe
2020-10-15 14:34     ` Oleg Nesterov
2020-10-15 14:54       ` Thomas Gleixner
2020-10-15 15:17         ` Oleg Nesterov
2020-10-16  9:55       ` Thomas Gleixner
2020-10-16 10:54         ` Oleg Nesterov
2020-10-16 13:07           ` Thomas Gleixner
2020-10-15 14:44   ` Oleg Nesterov
2020-10-20 10:57   ` introduce asm-generic/thread_info.h ? Oleg Nesterov
2020-10-15 13:17 ` [PATCH 5/5] task_work: use TIF_NOTIFY_SIGNAL if available Jens Axboe
2020-10-15 15:49   ` Oleg Nesterov
2020-10-15 18:39     ` Jens Axboe
2020-10-16  9:00       ` Thomas Gleixner
2020-10-16  9:39         ` Thomas Gleixner
2020-10-16 13:35           ` Jens Axboe
2020-10-16 14:17             ` Thomas Gleixner
2020-10-16 14:51               ` Oleg Nesterov
2020-10-16 14:53                 ` Jens Axboe
2020-10-16 18:03                   ` Thomas Gleixner
2020-10-16 18:05                     ` Jens Axboe
2020-10-16 13:33         ` Jens Axboe
2020-10-16 14:11           ` Thomas Gleixner
2020-10-16 14:22             ` Jens Axboe

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