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From: Maxime Ripard <maxime.ripard@bootlin.com>
To: Yizhuo Zhai <yzhai003@ucr.edu>
Cc: David Miller <davem@davemloft.net>,
	Chengyu Song <csong@cs.ucr.edu>, Zhiyun Qian <zhiyunq@cs.ucr.edu>,
	Giuseppe Cavallaro <peppe.cavallaro@st.com>,
	Alexandre Torgue <alexandre.torgue@st.com>,
	Chen-Yu Tsai <wens@csie.org>,
	netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: stmmac: Variable "val" in function sun8i_dwmac_set_syscon() could be uninitialized
Date: Thu, 7 Feb 2019 10:24:54 +0100	[thread overview]
Message-ID: <20190207092454.xq5jvnfnuhcp37nm@flea> (raw)
In-Reply-To: <CABvMjLTymaszPdX5afOHFfFBS1AueVzRVra5_QUr144GahH5gQ@mail.gmail.com>

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On Wed, Feb 06, 2019 at 09:53:16PM -0800, Yizhuo Zhai wrote:
> 
> 
> On Wed, Feb 6, 2019 at 9:52 PM Yizhuo Zhai <yzhai003@ucr.edu> wrote:
> >
> > Thanks, but why initialization matters here? Is performance the main concern?
> >
> > On Wed, Feb 6, 2019 at 8:17 PM David Miller <davem@davemloft.net> wrote:
> >>
> >> From: Yizhuo <yzhai003@ucr.edu>
> >> Date: Tue,  5 Feb 2019 14:15:59 -0800
> >>
> >> > @@ -639,9 +639,14 @@ static int sun8i_dwmac_set_syscon(struct stmmac_priv *priv)
> >> >       struct sunxi_priv_data *gmac = priv->plat->bsp_priv;
> >> >       struct device_node *node = priv->device->of_node;
> >> >       int ret;
> >> > -     u32 reg, val;
> >> > +     u32 reg, val = 0;
> >> > +
> >> > +     ret = regmap_read(gmac->regmap, SYSCON_EMAC_REG, &val);
> >> > +     if (ret) {
> >> > +             dev_err(priv->device, "Fail to read SYSCON_EMAC_REG.\n");
> >> > +             return ret;
> >> > +     }
> >>
> >> I agree with the other reviewer that since you check 'ret' the initialization of
> >> 'val' is no longer needed.
>
> Thanks, but why initialization matters here? Is performance the main
> concern?

Not really, but if we turn this the other way around, why should we do
something that doesn't bring anything?

Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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WARNING: multiple messages have this Message-ID (diff)
From: Maxime Ripard <maxime.ripard@bootlin.com>
To: Yizhuo Zhai <yzhai003@ucr.edu>
Cc: Chengyu Song <csong@cs.ucr.edu>,
	Alexandre Torgue <alexandre.torgue@st.com>,
	netdev@vger.kernel.org, Zhiyun Qian <zhiyunq@cs.ucr.edu>,
	linux-kernel@vger.kernel.org, Chen-Yu Tsai <wens@csie.org>,
	Giuseppe Cavallaro <peppe.cavallaro@st.com>,
	David Miller <davem@davemloft.net>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] net: stmmac: Variable "val" in function sun8i_dwmac_set_syscon() could be uninitialized
Date: Thu, 7 Feb 2019 10:24:54 +0100	[thread overview]
Message-ID: <20190207092454.xq5jvnfnuhcp37nm@flea> (raw)
In-Reply-To: <CABvMjLTymaszPdX5afOHFfFBS1AueVzRVra5_QUr144GahH5gQ@mail.gmail.com>


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On Wed, Feb 06, 2019 at 09:53:16PM -0800, Yizhuo Zhai wrote:
> 
> 
> On Wed, Feb 6, 2019 at 9:52 PM Yizhuo Zhai <yzhai003@ucr.edu> wrote:
> >
> > Thanks, but why initialization matters here? Is performance the main concern?
> >
> > On Wed, Feb 6, 2019 at 8:17 PM David Miller <davem@davemloft.net> wrote:
> >>
> >> From: Yizhuo <yzhai003@ucr.edu>
> >> Date: Tue,  5 Feb 2019 14:15:59 -0800
> >>
> >> > @@ -639,9 +639,14 @@ static int sun8i_dwmac_set_syscon(struct stmmac_priv *priv)
> >> >       struct sunxi_priv_data *gmac = priv->plat->bsp_priv;
> >> >       struct device_node *node = priv->device->of_node;
> >> >       int ret;
> >> > -     u32 reg, val;
> >> > +     u32 reg, val = 0;
> >> > +
> >> > +     ret = regmap_read(gmac->regmap, SYSCON_EMAC_REG, &val);
> >> > +     if (ret) {
> >> > +             dev_err(priv->device, "Fail to read SYSCON_EMAC_REG.\n");
> >> > +             return ret;
> >> > +     }
> >>
> >> I agree with the other reviewer that since you check 'ret' the initialization of
> >> 'val' is no longer needed.
>
> Thanks, but why initialization matters here? Is performance the main
> concern?

Not really, but if we turn this the other way around, why should we do
something that doesn't bring anything?

Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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_______________________________________________
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2019-02-07  9:25 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-05 22:15 [PATCH] net: stmmac: Variable "val" in function sun8i_dwmac_set_syscon() could be uninitialized Yizhuo
2019-02-05 22:15 ` Yizhuo
2019-02-06  9:18 ` Maxime Ripard
2019-02-06  9:18   ` Maxime Ripard
2019-02-07  4:17 ` David Miller
2019-02-07  4:17   ` David Miller
     [not found]   ` <CABvMjLQ6MYtGYeLxwceZsvcyn4oScgMo+BGQMHw7SkZ1uxFmHQ@mail.gmail.com>
2019-02-07  5:53     ` Yizhuo Zhai
2019-02-07  5:53       ` Yizhuo Zhai
2019-02-07  9:24       ` Maxime Ripard [this message]
2019-02-07  9:24         ` Maxime Ripard
2019-02-07 17:48         ` Yizhuo Zhai
2019-02-07 17:48           ` Yizhuo Zhai
2019-02-07 17:53     ` David Miller
2019-02-07 17:53       ` David Miller
2019-02-07 17:46 Yizhuo
2019-02-07 17:46 ` Yizhuo
2019-02-08  7:44 ` Maxime Ripard
2019-02-08  7:44   ` Maxime Ripard
2019-02-09  7:01 ` David Miller
2019-02-09  7:01   ` David Miller
2019-08-30 22:29   ` Yizhuo Zhai
2019-08-30 22:29     ` Yizhuo Zhai
2019-08-31  0:37     ` David Miller
2019-08-31  0:37       ` David Miller

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