linux-kernel - Re: [PATCH v2] ahci: qoriq: fixed using uninitialized variable warnings

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Message-ID: <20150910142214.GA8114@mtj.duckdns.org>
Date:	Thu, 10 Sep 2015 10:22:14 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Yuantian.Tang@...escale.com
Cc:	hdegoede@...hat.com, linux-ide@...r.kernel.org,
	linux-kernel@...r.kernel.org, fengguang.wu@...el.com
Subject: Re: [PATCH v2] ahci: qoriq: fixed using uninitialized variable
 warnings

(cc'ing Fengguang, hi!)

Fengguang, this is about kbuild test robot warning titled
"drivers/ata/ahci_qoriq.c:70:6: warning: 'px_cmd' may be used
uninitialized in this function".  Yuantian can't reproduce the warning
and I'm wondering whether the below patch would make the warning go
away.  Which gcc was the build bot using?  Would it be possible to
verify that the following patch makes the warning go away?

Thanks.

On Thu, Sep 10, 2015 at 03:13:32PM +0800, Yuantian.Tang@...escale.com wrote:
> From: Tang Yuantian <Yuantian.Tang@...escale.com>
> 
> kbuild test robot reports the warnings:
> drivers/ata/ahci_qoriq.c: In function 'ahci_qoriq_hardreset':
> >> include/asm-generic/io.h:163:2: warning: 'px_is' may be used
> >> uninitialized in this function [-Wuninitialized]
> drivers/ata/ahci_qoriq.c:70:14: note: 'px_is' was declared here
> >> include/asm-generic/io.h:163:2: warning: 'px_cmd' may be used
> >> uninitialized in this function [-Wuninitialized]
> drivers/ata/ahci_qoriq.c:70:6: note: 'px_cmd' was declared here
> 
> This patch fixed it by making type as a local variable.
> 
> Signed-off-by: Tang Yuantian <Yuantian.Tang@...escale.com>
> ---
> v2:
> 	- try another way to fix the warnings
> 	- remove clean up code
> 
>  drivers/ata/ahci_qoriq.c | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/ata/ahci_qoriq.c b/drivers/ata/ahci_qoriq.c
> index e5e4988..0d06e76 100644
> --- a/drivers/ata/ahci_qoriq.c
> +++ b/drivers/ata/ahci_qoriq.c
> @@ -48,9 +48,9 @@ enum ahci_qoriq_type {
>  	AHCI_LS2085A,
>  };
>  
> +enum ahci_qoriq_type type;
>  struct ahci_qoriq_priv {
>  	struct ccsr_ahci *reg_base;
> -	enum ahci_qoriq_type type;
>  	void __iomem *ecc_addr;
>  };
>  
> @@ -71,7 +71,6 @@ static int ahci_qoriq_hardreset(struct ata_link *link, unsigned int *class,
>  	struct ata_port *ap = link->ap;
>  	struct ahci_port_priv *pp = ap->private_data;
>  	struct ahci_host_priv *hpriv = ap->host->private_data;
> -	struct ahci_qoriq_priv *qoriq_priv = hpriv->plat_data;
>  	u8 *d2h_fis = pp->rx_fis + RX_FIS_D2H_REG;
>  	struct ata_taskfile tf;
>  	bool online;
> @@ -92,7 +91,7 @@ static int ahci_qoriq_hardreset(struct ata_link *link, unsigned int *class,
>  	 * After the sequence is complete, software should restore the
>  	 * PxCMD and PxIS with the stored values.
>  	 */
> -	if (qoriq_priv->type == AHCI_LS1021A) {
> +	if (type == AHCI_LS1021A) {
>  		px_cmd = readl(port_mmio + PORT_CMD);
>  		px_is = readl(port_mmio + PORT_IRQ_STAT);
>  	}
> @@ -106,7 +105,7 @@ static int ahci_qoriq_hardreset(struct ata_link *link, unsigned int *class,
>  				 ahci_check_ready);
>  
>  	/* restore the PxCMD and PxIS on ls1021 */
> -	if (qoriq_priv->type == AHCI_LS1021A) {
> +	if (type == AHCI_LS1021A) {
>  		px_val = readl(port_mmio + PORT_CMD);
>  		if (px_val != px_cmd)
>  			writel(px_cmd, port_mmio + PORT_CMD);
> @@ -146,7 +145,7 @@ static int ahci_qoriq_phy_init(struct ahci_host_priv *hpriv)
>  	struct ahci_qoriq_priv *qpriv = hpriv->plat_data;
>  	void __iomem *reg_base = hpriv->mmio;
>  
> -	switch (qpriv->type) {
> +	switch (type) {
>  	case AHCI_LS1021A:
>  		writel(SATA_ECC_DISABLE, qpriv->ecc_addr);
>  		writel(AHCI_PORT_PHY_1_CFG, reg_base + PORT_PHY1);
> @@ -188,9 +187,9 @@ static int ahci_qoriq_probe(struct platform_device *pdev)
>  	if (!qoriq_priv)
>  		return -ENOMEM;
>  
> -	qoriq_priv->type = (enum ahci_qoriq_type)of_id->data;
> +	type = (enum ahci_qoriq_type)of_id->data;
>  
> -	if (qoriq_priv->type == AHCI_LS1021A) {
> +	if (type == AHCI_LS1021A) {
>  		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
>  				"sata-ecc");
>  		qoriq_priv->ecc_addr = devm_ioremap_resource(dev, res);
> -- 
> 2.1.0.27.g96db324
> 

-- 
tejun
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