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From: Thomas Gleixner <tglx@linutronix.de>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
	linux-kernel@vger.kernel.org, io-uring@vger.kernel.org,
	peterz@infradead.org
Subject: Re: [PATCH 4/5] x86: wire up TIF_NOTIFY_SIGNAL
Date: Fri, 16 Oct 2020 15:07:14 +0200	[thread overview]
Message-ID: <87imbatj3x.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20201016105415.GA21989@redhat.com>

On Fri, Oct 16 2020 at 12:54, Oleg Nesterov wrote:
> On 10/16, Thomas Gleixner wrote:
>
> But again, I won't argue. And to remind, we do not really need to touch
> arch_do_signal() at all. We can just add
>
> 	if (test_thread_flag(TIF_NOTIFY_SIGNAL))
> 		tracehook_notify_signal();
>
> 	if (!task_sigpending(current))
> 		return 0;
>
> at the start of get_signal() and avoid the code duplication automatically.

That works as well and is smart, but it's completely non obvious while

     if (ti_work & _TIF_NOTIFY_SIGNAL)
            tracehook_notify_signal();

     arch_do_signal_or_restart(ti_work & _TIF_SIGPENDING);

makes it entirely clear to follow the logic and it just operates on
cached ti_work.

You can still do this for the non generic entry architectures:

     if (!IS_ENABLED(CONFIG_GENERIC_ENTRY) &&
     	 (test_thread_flag(TIF_NOTIFY_SIGNAL))
 		tracehook_notify_signal();

to avoid the churn in arch/*.

Thanks,

        tglx

  reply	other threads:[~2020-10-16 13:07 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
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 [this message]
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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