linux-kernel - Re: [GIT pull] locking/urgent for v5.10-rc6

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Message-ID: <CAHk-=wgTsvLivVr05CbfUEUv+maq+qyvsfXTA0W278f_JbJciw@mail.gmail.com>
Date:   Tue, 1 Dec 2020 11:45:25 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "the arch/x86 maintainers" <x86@...nel.org>
Subject: Re: [GIT pull] locking/urgent for v5.10-rc6

On Mon, Nov 30, 2020 at 11:56 PM Peter Zijlstra <peterz@...radead.org> wrote:
>
> So even if an architecture needs to enable interrupts on idle, we need
> it disabled again when coming out. So we might as well have the arch
> idle routine then be: STI; HLT; CLI; because then architectures than can
> idle with interrupts disabled can avoid mucking about with the interrupt
> state entirely.

But that's not what the code is doing.

Go look at it.

It does sti;hlt;cli;pushf;cli;sti.

All for no good reason - because the code is structured so that even
if all the tracking and lockdep is disabled, the pointless "let's
protect the tracking from interrupts" is still there.

See what I am complaining about?

                Linus