linux-kernel - Re: [PATCH v4] riscv: patch: Fixup lockdep warning in stop

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Date:   Wed, 15 Feb 2023 11:45:32 +0800
From:   Changbin Du <changbin.du@...wei.com>
To:     Guo Ren <guoren@...nel.org>
CC:     Conor Dooley <conor@...nel.org>,
        Changbin Du <changbin.du@...wei.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Hui Wang <hw.huiwang@...wei.com>,
        <linux-riscv@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Zong Li <zong.li@...ive.com>
Subject: Re: [PATCH v4] riscv: patch: Fixup lockdep warning in stop_machine

On Wed, Feb 15, 2023 at 09:24:33AM +0800, Guo Ren wrote:
> On Wed, Feb 15, 2023 at 8:22 AM Conor Dooley <conor@...nel.org> wrote:
> >
> > Hey Changbin,
> >
> > On Thu, Feb 02, 2023 at 07:41:16PM +0800, Changbin Du wrote:
> > > The task of ftrace_arch_code_modify(_post)_prepare() caller is
> > > stop_machine, whose caller and work thread are of different tasks. The
> > > lockdep checker needs the same task context, or it's wrong. That means
> > > it's a bug here to use lockdep_assert_held because we don't guarantee
> > > the same task context.
> I'm trying to delete all stop_machine in riscv, from ftrace to kprobe.
> When I have done, we needn't this patch.
>
Which approch would you use? I looked through the riscv-spec, but didn't find any
description abount concurrent modification and execution.

> > >
> > > 2.25.1
> > >
> 
> 
> 
> -- 
> Best Regards
>  Guo Ren

-- 
Cheers,
Changbin Du