Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20221214191355.GA2596199@paulmck-ThinkPad-P17-Gen-1>
 <CAEXW_YTztHvaXJG9jQmQ13tF2HdCy8+TbvBDCYWd98tMrsE-vw@mail.gmail.com>
 <20221214212455.GA4001@paulmck-ThinkPad-P17-Gen-1> <CAEXW_YQp5K2iy0ULnFOVKQit3T+OM_vY29ZcLu6drNEt-ex1QQ@mail.gmail.com>
In-Reply-To: <CAEXW_YQp5K2iy0ULnFOVKQit3T+OM_vY29ZcLu6drNEt-ex1QQ@mail.gmail.com>
From:   Joel Fernandes <joel@joelfernandes.org>
Date:   Wed, 14 Dec 2022 23:10:43 +0000
Message-ID: <CAEXW_YRvSrD40WJ+8GicWB5NN8QyLLoUzRS9j8Tc9CMvojKO0g@mail.gmail.com>
Subject: Re: [PATCH RFC] srcu: Yet more detail for srcu_readers_active_idx_check()
 comments
To:     paulmck@kernel.org
Cc:     boqun.feng@gmail.com, frederic@kernel.org, neeraj.iitr10@gmail.com,
        urezki@gmail.com, rcu@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Wed, Dec 14, 2022 at 11:07 PM Joel Fernandes <joel@joelfernandes.org> wrote:
>
> On Wed, Dec 14, 2022 at 9:24 PM Paul E. McKenney <paulmck@kernel.org> wrote:
> > > I also did not get why you care about readers that come and ago (you
> > > mentioned the first reader seeing incorrect idx and the second reader
> > > seeing the right flipped one, etc). Those readers are irrelevant
> > > AFAICS since they came and went, and need not be waited on , right?.
> >
> > The comment is attempting to show (among other things) that we don't
> > need to care about readers that come and go more than twice during that
> > critical interval of time during the counter scans.
>
> Why do we need to care about readers that come and go even once? Once
> they are gone, they have already done an unlock() and their RSCS is
> over, so they need to be considered AFAICS.
>

Aargh, I meant: "so they need to be considered AFAICS".

Thanks.