linux-kernel - Re: [PATCH V2 2/3] riscv: Add support for restartable sequence

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Message-ID: <CABvJ_xgLgk0woE-X2mjtSUzO5ykzmu+qKkToDiskOrCQ1u=Pog@mail.gmail.com>
Date:   Wed, 21 Jul 2021 11:19:24 +0800
From:   Vincent Chen <vincent.chen@...ive.com>
To:     Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc:     Guo Ren <guoren@...ux.alibaba.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        linux-kselftest <linux-kselftest@...r.kernel.org>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH V2 2/3] riscv: Add support for restartable sequence

On Mon, Jul 19, 2021 at 10:43 PM Mathieu Desnoyers
<mathieu.desnoyers@...icios.com> wrote:
>
> ----- On Mar 9, 2020, at 1:59 AM, Vincent Chen vincent.chen@...ive.com wrote:
> [...]
> > --- a/arch/riscv/kernel/signal.c
> > +++ b/arch/riscv/kernel/signal.c
> > @@ -234,6 +234,7 @@ static void handle_signal(struct ksignal *ksig, struct
> > pt_regs *regs)
> >       sigset_t *oldset = sigmask_to_save();
> >       int ret;
> >
> > +     rseq_signal_deliver(ksig, regs);
> >       /* Are we from a system call? */
> >       if (regs->cause == EXC_SYSCALL) {
>
> [...]
>
> As Al Viro pointed out on IRC, the rseq_signal_deliver() should go after syscall
> restart handling, similarly to what is done on every other supported architecture.

Thanks for the notification. I will adjust the porting and try to send
the patch again for review.


>
> Note that there is already an upstream commit derived on this non-upstream patch:
>
> commit 9866d141a097 ("csky: Add support for restartable sequence")
>
> which is broken in the same way.
>
> I'm not sure why I was never CC'd on the csky patch. Considering that nobody
> bothered to implement the rseq selftests for csky, I don't see how any of
> this is tested. I would favor a revert of that commit until the testing glue
> is contributed. Unfortunately, the csky commit has been upstream since v5.7.
>
> Thanks,
>
> Mathieu
>
>
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com