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From:   Chuhong Yuan <hslester96@gmail.com>
Date:   Fri, 2 Aug 2019 22:27:42 +0800
Message-ID: <CANhBUQ2TRr4RuSmjaRYPXHZpVw_-2awXvWNjjdvV_z1yoGdkXA@mail.gmail.com>
Subject: Re: [PATCH v2 1/2] cxgb4: sched: Use refcount_t for refcount
To:     Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc:     Vishal Kulkarni <vishal@chelsio.com>,
        "David S . Miller" <davem@davemloft.net>,
        Network Development <netdev@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
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Willem de Bruijn <willemdebruijn.kernel@gmail.com> =E4=BA=8E2019=E5=B9=B48=
=E6=9C=882=E6=97=A5=E5=91=A8=E4=BA=94 =E4=B8=8B=E5=8D=889:40=E5=86=99=E9=81=
=93=EF=BC=9A
>
> On Fri, Aug 2, 2019 at 4:36 AM Chuhong Yuan <hslester96@gmail.com> wrote:
> >
> > refcount_t is better for reference counters since its
> > implementation can prevent overflows.
> > So convert atomic_t ref counters to refcount_t.
> >
> > Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
> > ---
> > Changes in v2:
> >   - Convert refcount from 0-base to 1-base.
>
> This changes the initial value from 0 to 1, but does not change the
> release condition. So this introduces an accounting bug?

I have noticed this problem and have checked other files which use refcount=
_t.
I find although the refcounts are 1-based, they still use
refcount_dec_and_test()
to check whether the resource should be released.
One example is drivers/char/mspec.c.
Therefore I think this is okay and do not change the release condition.