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Date:   Thu, 15 Oct 2020 16:36:17 +0200
From:   Oleg Nesterov <oleg@redhat.com>
To:     Jens Axboe <axboe@kernel.dk>
Cc:     Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org,
        io-uring@vger.kernel.org, peterz@infradead.org
Subject: Re: [PATCH 4/5] x86: wire up TIF_NOTIFY_SIGNAL
Message-ID: <20201015143616.GD24156@redhat.com>
References: <20201015131701.511523-1-axboe@kernel.dk>
 <20201015131701.511523-5-axboe@kernel.dk>
 <87o8l3a8af.fsf@nanos.tec.linutronix.de>
 <da84a2a7-f94a-d0aa-14e0-3925f758aa0e@kernel.dk>
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On 10/15, Jens Axboe wrote:
>
> static void handle_signal_work(ti_work, regs)
> {
> 	if (ti_work & _TIF_NOTIFY_SIGNAL)
>         	tracehook_notify_signal();
>
> 	if (ti_work & _TIF_SIGPENDING)
>         	arch_do_signal(regs);
> }
>
> and then we can skip modifying arch_do_signal() all together, as it'll
> only be called if _TIF_SIGPENDING is set.

No, this can't work. We need to restart the syscall if TIF_NOTIFY_SIGNAL.

Oleg.