[PATCH] usb: mtu3: allocate phys with ssusb

[PATCH] usb: mtu3: allocate phys with ssusb

[Rosen Penev]

Use a flexible array member to combine allocations. Allows removal of a
pointless branch. A size of 0 means phys are not allocated.

Add __counted_by for extra runtime analysis.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/usb/mtu3/mtu3.h      |  2 +-
 drivers/usb/mtu3/mtu3_plat.c | 18 ++++++------------
 2 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/drivers/usb/mtu3/mtu3.h b/drivers/usb/mtu3/mtu3.h
index ba5a63669e5f..d71849388602 100644
--- a/drivers/usb/mtu3/mtu3.h
+++ b/drivers/usb/mtu3/mtu3.h
@@ -252,7 +252,6 @@ struct ssusb_mtk {
 	struct mtu3 *u3d;
 	void __iomem *mac_base;
 	void __iomem *ippc_base;
-	struct phy **phys;
 	int num_phys;
 	int wakeup_irq;
 	/* common power & clock */
@@ -272,6 +271,7 @@ struct ssusb_mtk {
 	struct regmap *uwk;
 	u32 uwk_reg_base;
 	u32 uwk_vers;
+	struct phy *phys[] __counted_by(num_phys);
 };
 
 /**
diff --git a/drivers/usb/mtu3/mtu3_plat.c b/drivers/usb/mtu3/mtu3_plat.c
index cc8a864dbd63..11a919fc3d47 100644
--- a/drivers/usb/mtu3/mtu3_plat.c
+++ b/drivers/usb/mtu3/mtu3_plat.c
@@ -240,17 +240,6 @@ static int get_ssusb_rscs(struct platform_device *pdev, struct ssusb_mtk *ssusb)
 	if (ret)
 		return ret;
 
-	ssusb->num_phys = of_count_phandle_with_args(node,
-			"phys", "#phy-cells");
-	if (ssusb->num_phys > 0) {
-		ssusb->phys = devm_kcalloc(dev, ssusb->num_phys,
-					sizeof(*ssusb->phys), GFP_KERNEL);
-		if (!ssusb->phys)
-			return -ENOMEM;
-	} else {
-		ssusb->num_phys = 0;
-	}
-
 	for (i = 0; i < ssusb->num_phys; i++) {
 		ssusb->phys[i] = devm_of_phy_get_by_index(dev, node, i);
 		if (IS_ERR(ssusb->phys[i])) {
@@ -330,12 +319,17 @@ static int mtu3_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct ssusb_mtk *ssusb;
 	int ret = -ENOMEM;
+	int num_phys;
 
+	num_phys = of_count_phandle_with_args(dev->of_node,
+			"phys", "#phy-cells");
 	/* all elements are set to ZERO as default value */
-	ssusb = devm_kzalloc(dev, sizeof(*ssusb), GFP_KERNEL);
+	ssusb = devm_kzalloc(dev, struct_size(ssusb, phys, num_phys), GFP_KERNEL);
 	if (!ssusb)
 		return -ENOMEM;
 
+	ssusb->num_phys = num_phys;
+
 	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
 	if (ret) {
 		dev_err(dev, "No suitable DMA config available\n");
-- 
2.53.0

Re: [PATCH] usb: mtu3: allocate phys with ssusb

[Greg Kroah-Hartman]

On Fri, Apr 10, 2026 at 08:57:31PM -0700, Rosen Penev wrote:
> Use a flexible array member to combine allocations. Allows removal of a
> pointless branch. A size of 0 means phys are not allocated.
> 
> Add __counted_by for extra runtime analysis.
> 
> Signed-off-by: Rosen Penev <rosenp@gmail.com>
> ---
>  drivers/usb/mtu3/mtu3.h      |  2 +-
>  drivers/usb/mtu3/mtu3_plat.c | 18 ++++++------------
>  2 files changed, 7 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/usb/mtu3/mtu3.h b/drivers/usb/mtu3/mtu3.h
> index ba5a63669e5f..d71849388602 100644
> --- a/drivers/usb/mtu3/mtu3.h
> +++ b/drivers/usb/mtu3/mtu3.h
> @@ -252,7 +252,6 @@ struct ssusb_mtk {
>  	struct mtu3 *u3d;
>  	void __iomem *mac_base;
>  	void __iomem *ippc_base;
> -	struct phy **phys;
>  	int num_phys;
>  	int wakeup_irq;
>  	/* common power & clock */
> @@ -272,6 +271,7 @@ struct ssusb_mtk {
>  	struct regmap *uwk;
>  	u32 uwk_reg_base;
>  	u32 uwk_vers;
> +	struct phy *phys[] __counted_by(num_phys);
>  };
>  
>  /**
> diff --git a/drivers/usb/mtu3/mtu3_plat.c b/drivers/usb/mtu3/mtu3_plat.c
> index cc8a864dbd63..11a919fc3d47 100644
> --- a/drivers/usb/mtu3/mtu3_plat.c
> +++ b/drivers/usb/mtu3/mtu3_plat.c
> @@ -240,17 +240,6 @@ static int get_ssusb_rscs(struct platform_device *pdev, struct ssusb_mtk *ssusb)
>  	if (ret)
>  		return ret;
>  
> -	ssusb->num_phys = of_count_phandle_with_args(node,
> -			"phys", "#phy-cells");
> -	if (ssusb->num_phys > 0) {
> -		ssusb->phys = devm_kcalloc(dev, ssusb->num_phys,
> -					sizeof(*ssusb->phys), GFP_KERNEL);
> -		if (!ssusb->phys)
> -			return -ENOMEM;
> -	} else {
> -		ssusb->num_phys = 0;
> -	}
> -
>  	for (i = 0; i < ssusb->num_phys; i++) {
>  		ssusb->phys[i] = devm_of_phy_get_by_index(dev, node, i);
>  		if (IS_ERR(ssusb->phys[i])) {
> @@ -330,12 +319,17 @@ static int mtu3_probe(struct platform_device *pdev)
>  	struct device *dev = &pdev->dev;
>  	struct ssusb_mtk *ssusb;
>  	int ret = -ENOMEM;
> +	int num_phys;
>  
> +	num_phys = of_count_phandle_with_args(dev->of_node,
> +			"phys", "#phy-cells");

You just caused a bug here if this returns a negative value.

How was this tested?

And why is it even needed?

thanks,

greg k-h