linux-kernel - Re: [PATCH V3] riscv: patch_text: Fixup last cpu should be master

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Date:   Thu, 7 Apr 2022 14:36:26 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Palmer Dabbelt <palmer@...osinc.com>
Cc:     Greg KH <gregkh@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        linux-arch <linux-arch@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Guo Ren <guoren@...ux.alibaba.com>,
        Masami Hiramatsu <mhiramat@...nel.org>, stable@...r.kernel.org
Subject: Re: [PATCH V3] riscv: patch_text: Fixup last cpu should be master

On Thu, Apr 7, 2022 at 3:06 AM Palmer Dabbelt <palmer@...osinc.com> wrote:
>
> On Wed, 06 Apr 2022 11:13:36 PDT (-0700), Greg KH wrote:
> > On Wed, Apr 06, 2022 at 10:16:49PM +0800, guoren@...nel.org wrote:
> >> From: Guo Ren <guoren@...ux.alibaba.com>
> >>
> >> These patch_text implementations are using stop_machine_cpuslocked
> >> infrastructure with atomic cpu_count. The original idea: When the
> >> master CPU patch_text, the others should wait for it. But current
> >> implementation is using the first CPU as master, which couldn't
> >> guarantee the remaining CPUs are waiting. This patch changes the
> >> last CPU as the master to solve the potential risk.
> >>
> >> Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
> >> Signed-off-by: Guo Ren <guoren@...nel.org>
> >> Acked-by: Palmer Dabbelt <palmer@...osinc.com>
> >> Reviewed-by: Masami Hiramatsu <mhiramat@...nel.org>
> >> Cc: <stable@...r.kernel.org>
> >> ---
> >>  arch/riscv/kernel/patch.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > What commit id does this change fix?
>
> I think it's been there since the beginning of our text patching, so
>
> Fixes: 043cb41a85de ("riscv: introduce interfaces to patch kernel code")
Yes, it the riscv origin.

>
> seems like the best bet, but I'll go take another look before merging
> it.  That's confusing here, as I acked it, but that was for an earlier
> version that touched more than one arch so it was more ambiguous as to
> which tree it was going through (IIRC I said one of those "LMK if you
> want it through my tree, but here's an Ack in case someone else wants to
> take it" sort of things, as I usually do when it's ambiguous).
Thx for the clarification, I would remove the acked in the next version.

>
> Without a changelog, cover letter, or the other patches in the set it's
> kind of hard to tell, though ;)
Okay, I should add a changelog for the patch with cover letter.


-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/