netdev - Re: [PATCH] [v2] test_rhashtable: remove semaphore usage

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Message-ID: <CAMuHMdWKLccPn0Orf=tv7Nb6YBhraxbL9O-ujXwq_ULoZOU7iA@mail.gmail.com>
Date:   Wed, 2 Jan 2019 11:05:12 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     netdev <netdev@...r.kernel.org>,
        "Acked-by : Phil Sutter" <phil@....cc>,
        Thomas Graf <tgraf@...g.ch>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        NeilBrown <neilb@...e.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] [v2] test_rhashtable: remove semaphore usage

Hi Arnd,

On Sun, Dec 16, 2018 at 8:50 PM Arnd Bergmann <arnd@...db.de> wrote:
> This is one of only two files that initialize a semaphore to a negative
> value. We don't really need the two semaphores here at all, but can do
> the same thing in more conventional and more effient way, by using a
> single waitqueue and an atomic thread counter.
>
> This gets us a little bit closer to eliminating classic semaphores from
> the kernel. It also fixes a corner case where we fail to continue after
> one of the threads fails to start up.
>
> An alternative would be to use a split kthread_create()+wake_up_process()
> and completely eliminate the separate synchronization.
>
> Acked-by: Phil Sutter <phil@....cc>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
> Changes from v1:
>  - rebase to mainline,
>  - fix pr_err() output
>  - bail out if interrupted

Now this is upstream as 809c67059162e7ba ("test_rhashtable: remove
semaphore usage"), I gave test_rhashtable a try again on m68k/ARAnyM.
And it succeeded, without my workaround from
https://www.mail-archive.com/netdev@vger.kernel.org/msg134240.html
Interestingly, it still succeeded without the workaround after reverting
809c67059162e7ba, so some other change during the last two years must
have fixed this.

I have no plans to bisect this, though.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds