Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <20191107193738.195914-1-edumazet@google.com> <20191108192448.GB20975@paulmck-ThinkPad-P72>
In-Reply-To: <20191108192448.GB20975@paulmck-ThinkPad-P72>
From:   Eric Dumazet <edumazet@google.com>
Date:   Fri, 8 Nov 2019 12:17:49 -0800
Message-ID: <CANn89iKNLESN7U7BtyzkC6WLVn__Hm727A5cRm6PDuzG5+E4vA@mail.gmail.com>
Subject: Re: [PATCH 1/2] list: add hlist_unhashed_lockless()
To:     "Paul E. McKenney" <paulmck@kernel.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Eric Dumazet <eric.dumazet@gmail.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, Nov 8, 2019 at 11:24 AM Paul E. McKenney <paulmck@kernel.org> wrote:
>
> On Thu, Nov 07, 2019 at 11:37:37AM -0800, Eric Dumazet wrote:
> > We would like to use hlist_unhashed() from timer_pending(),
> > which runs without protection of a lock.
> >
> > Note that other callers might also want to use this variant.
> >
> > Instead of forcing a READ_ONCE() for all hlist_unhashed()
> > callers, add a new helper with an explicit _lockless suffix
> > in the name to better document what is going on.
> >
> > Also add various WRITE_ONCE() in __hlist_del(), hlist_add_head()
> > and hlist_add_before()/hlist_add_behind() to pair with
> > the READ_ONCE().
> >
> > Signed-off-by: Eric Dumazet <edumazet@google.com>
> > Cc: "Paul E. McKenney" <paulmck@kernel.org>
> > Cc: Thomas Gleixner <tglx@linutronix.de>
>
> I have queued this, but if you prefer it go some other way:
>
> Acked-by: Paul E. McKenney <paulmck@kernel.org>
>
> But shouldn't the uses in include/linux/rculist.h also be converted
> into the patch below?  If so, I will squash the following into your
> patch.
>
>                                                 Thanx, Paul
>
> ------------------------------------------------------------------------

Agreed, thanks for the addition of this Paul.