linux-kernel - Re: [PATCH 10/15] iio: sx9310: Simplify error return handling

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Date:   Tue, 28 Jul 2020 15:23:29 -0600
From:   Daniel Campello <campello@...omium.org>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     LKML <devicetree@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Douglas Anderson <dianders@...omium.org>,
        Enrico Granata <egranata@...omium.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-iio <linux-iio@...r.kernel.org>
Subject: Re: [PATCH 10/15] iio: sx9310: Simplify error return handling

On Tue, Jul 28, 2020 at 1:40 PM Stephen Boyd <swboyd@...omium.org> wrote:
>
> Quoting Daniel Campello (2020-07-28 08:12:53)
> > @@ -368,13 +368,13 @@ static int sx9310_wait_for_sample(struct sx9310_data *data)
> >  static int sx9310_read_proximity(struct sx9310_data *data,
> >                                  const struct iio_chan_spec *chan, int *val)
> >  {
> > -       int ret = 0;
> > +       int ret;
> >         __be16 rawval;
> >
> >         mutex_lock(&data->mutex);
> >
> >         ret = sx9310_get_read_channel(data, chan->channel);
> > -       if (ret < 0)
> > +       if (ret)
> >                 goto out;
> >
> >         if (data->client->irq) {
> > @@ -394,11 +394,11 @@ static int sx9310_read_proximity(struct sx9310_data *data,
> >
> >         mutex_lock(&data->mutex);
> >
> > -       if (ret < 0)
> > +       if (ret)
> >                 goto out_disable_irq;
>
> Why is this condition checked after grabbing the mutex? Shouldn't it be
> checked before grabbing the mutex? Or is that supposed to be a
> mutex_unlock()?
We acquire the lock before jumping to out_disable_irq which is before
a mutex_unlock()
>
> >
> >         ret = sx9310_read_prox_data(data, chan, &rawval);
> > -       if (ret < 0)
> > +       if (ret)
> >                 goto out_disable_irq;
> >
> >         *val = sign_extend32(be16_to_cpu(rawval),