linux-kernel - Re: [PATCH 3/6] kernel: split syscall restart from signal handling

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Message-ID: <20201008144539.GJ9995@redhat.com>
Date:   Thu, 8 Oct 2020 16:45:40 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     linux-kernel@...r.kernel.org, io-uring@...r.kernel.org,
        peterz@...radead.org, tglx@...utronix.de
Subject: Re: [PATCH 3/6] kernel: split syscall restart from signal handling

On 10/08, Jens Axboe wrote:
>
> On 10/8/20 8:21 AM, Oleg Nesterov wrote:
> > 
> > Can't we avoid this patch and the and simplify the change in
> > exit_to_user_mode_loop() from the next patch? Can't the much more simple
> > patch below work?
> > 
> > Then later we can even change arch_do_signal() to accept the additional
> > argument, ti_work, so that it can use ti_work & TIF_NOTIFY_SIGNAL/SIGPENDING
> > instead of test_thread_flag/task_sigpending.
> 
> Yeah I guess that would be a bit simpler, maybe I'm too focused on
> decoupling the two. But if we go this route, and avoid sighand->lock for
> just having TIF_NOTIFY_SIGNAL set, then that should be functionally
> equivalent as far as I'm concerned.

Not sure I understand... I think that the change I propose is functionally
equivalent or I missed something.

> I'll make the reduction, I'd prefer to keep this as small/simple as
> possible initially.

Great, thanks.

Oleg.