linux-kernel - Re: [PATCH] [media] tda18212: tda18218: use 'val' if initialized

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Date:	Tue, 06 Nov 2012 01:19:38 +0200
From:	Antti Palosaari <crope@....fi>
To:	Paul Bolle <pebolle@...cali.nl>
CC:	Mauro Carvalho Chehab <mchehab@...radead.org>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [media] tda18212: tda18218: use 'val' if initialized

On 11/01/2012 11:00 PM, Paul Bolle wrote:
> Commits e666a44fa313cb9329c0381ad02fc6ee1e21cb31 ("[media] tda18212:
> silence compiler warning") and e0e52d4e9f5bce7ea887027c127473eb654a5a04
> ("[media] tda18218: silence compiler warning") silenced warnings
> equivalent to these:
>      drivers/media/tuners/tda18212.c: In function ‘tda18212_attach’:
>      drivers/media/tuners/tda18212.c:299:2: warning: ‘val’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>      drivers/media/tuners/tda18218.c: In function ‘tda18218_attach’:
>      drivers/media/tuners/tda18218.c:305:2: warning: ‘val’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>
> But in both cases 'val' will still be used uninitialized if the calls
> of tda18212_rd_reg() or tda18218_rd_reg() fail. Fix this by only
> printing the "chip id" if the calls of those functions were successful.
> This allows to drop the uninitialized_var() stopgap measure.
>
> Also stop printing the return values of tda18212_rd_reg() or
> tda18218_rd_reg(), as these are not interesting.
>
> Signed-off-by: Paul Bolle <pebolle@...cali.nl>

Acked-by: Antti Palosaari <crope@....fi>
Reviewed-by: Antti Palosaari <crope@....fi>

That patch does not make much sense, but I don't still see any reason to 
reject it.

> ---
> 0) Compile tested only.
>
>   drivers/media/tuners/tda18212.c | 6 +++---
>   drivers/media/tuners/tda18218.c | 6 +++---
>   2 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/media/tuners/tda18212.c b/drivers/media/tuners/tda18212.c
> index 5d9f028..e4a84ee 100644
> --- a/drivers/media/tuners/tda18212.c
> +++ b/drivers/media/tuners/tda18212.c
> @@ -277,7 +277,7 @@ struct dvb_frontend *tda18212_attach(struct dvb_frontend *fe,
>   {
>   	struct tda18212_priv *priv = NULL;
>   	int ret;
> -	u8 uninitialized_var(val);
> +	u8 val;
>
>   	priv = kzalloc(sizeof(struct tda18212_priv), GFP_KERNEL);
>   	if (priv == NULL)
> @@ -296,8 +296,8 @@ struct dvb_frontend *tda18212_attach(struct dvb_frontend *fe,
>   	if (fe->ops.i2c_gate_ctrl)
>   		fe->ops.i2c_gate_ctrl(fe, 0); /* close I2C-gate */
>
> -	dev_dbg(&priv->i2c->dev, "%s: ret=%d chip id=%02x\n", __func__, ret,
> -			val);
> +	if (!ret)
> +		dev_dbg(&priv->i2c->dev, "%s: chip id=%02x\n", __func__, val);
>   	if (ret || val != 0xc7) {
>   		kfree(priv);
>   		return NULL;
> diff --git a/drivers/media/tuners/tda18218.c b/drivers/media/tuners/tda18218.c
> index 1819853..2d31aeb 100644
> --- a/drivers/media/tuners/tda18218.c
> +++ b/drivers/media/tuners/tda18218.c
> @@ -277,7 +277,7 @@ struct dvb_frontend *tda18218_attach(struct dvb_frontend *fe,
>   	struct i2c_adapter *i2c, struct tda18218_config *cfg)
>   {
>   	struct tda18218_priv *priv = NULL;
> -	u8 uninitialized_var(val);
> +	u8 val;
>   	int ret;
>   	/* chip default registers values */
>   	static u8 def_regs[] = {
> @@ -302,8 +302,8 @@ struct dvb_frontend *tda18218_attach(struct dvb_frontend *fe,
>
>   	/* check if the tuner is there */
>   	ret = tda18218_rd_reg(priv, R00_ID, &val);
> -	dev_dbg(&priv->i2c->dev, "%s: ret=%d chip id=%02x\n", __func__, ret,
> -			val);
> +	if (!ret)
> +		dev_dbg(&priv->i2c->dev, "%s: chip id=%02x\n", __func__, val);
>   	if (ret || val != def_regs[R00_ID]) {
>   		kfree(priv);
>   		return NULL;
>


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