[PATCH] usb: typec: intel_pmc_mux: combine kzalloc + kcalloc

[PATCH] usb: typec: intel_pmc_mux: combine kzalloc + kcalloc

[Rosen Penev]

A flexible array member can be used to combine allocations and simplify
handling slightly.

Add __counted_by for extra runtime analysis.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/usb/typec/mux/intel_pmc_mux.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/typec/mux/intel_pmc_mux.c b/drivers/usb/typec/mux/intel_pmc_mux.c
index 1698428654ab..8b0a3dd3f940 100644
--- a/drivers/usb/typec/mux/intel_pmc_mux.c
+++ b/drivers/usb/typec/mux/intel_pmc_mux.c
@@ -151,13 +151,14 @@ struct pmc_usb {
 	u8 num_ports;
 	struct device *dev;
 	struct intel_scu_ipc_dev *ipc;
-	struct pmc_usb_port *port;
 	struct acpi_device *iom_adev;
 	void __iomem *iom_base;
 	u32 iom_port_status_offset;
 	u8 iom_port_status_size;
 
 	struct dentry *dentry;
+
+	struct pmc_usb_port port[] __counted_by(num_ports);
 };
 
 static struct dentry *pmc_mux_debugfs_root;
@@ -731,27 +732,26 @@ static int pmc_usb_probe(struct platform_device *pdev)
 {
 	struct fwnode_handle *fwnode = NULL;
 	struct pmc_usb *pmc;
+	u8 num_ports;
 	int i = 0;
 	int ret;
 
-	pmc = devm_kzalloc(&pdev->dev, sizeof(*pmc), GFP_KERNEL);
-	if (!pmc)
-		return -ENOMEM;
-
 	device_for_each_child_node(&pdev->dev, fwnode)
-		pmc->num_ports++;
+		num_ports++;
 
 	/* The IOM microcontroller has a limitation of max 4 ports. */
-	if (pmc->num_ports > 4) {
+	if (num_ports > 4) {
 		dev_err(&pdev->dev, "driver limited to 4 ports\n");
 		return -ERANGE;
 	}
 
-	pmc->port = devm_kcalloc(&pdev->dev, pmc->num_ports,
-				 sizeof(struct pmc_usb_port), GFP_KERNEL);
-	if (!pmc->port)
+	pmc = devm_kzalloc(&pdev->dev, struct_size(pmc, port, num_ports),
+			GFP_KERNEL);
+	if (!pmc)
 		return -ENOMEM;
 
+	pmc->num_ports = num_ports;
+
 	pmc->ipc = devm_intel_scu_ipc_dev_get(&pdev->dev);
 	if (!pmc->ipc)
 		return -EPROBE_DEFER;
-- 
2.53.0

Re: [PATCH] usb: typec: intel_pmc_mux: combine kzalloc + kcalloc

[Heikki Krogerus]

Hi Rosen,

On Fri, Apr 10, 2026 at 07:36:42PM -0700, Rosen Penev wrote:
> A flexible array member can be used to combine allocations and simplify
> handling slightly.
> 
> Add __counted_by for extra runtime analysis.

One nitpick below.
Otherwise this looks okay to me.

> Signed-off-by: Rosen Penev <rosenp@gmail.com>
> ---
>  drivers/usb/typec/mux/intel_pmc_mux.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/usb/typec/mux/intel_pmc_mux.c b/drivers/usb/typec/mux/intel_pmc_mux.c
> index 1698428654ab..8b0a3dd3f940 100644
> --- a/drivers/usb/typec/mux/intel_pmc_mux.c
> +++ b/drivers/usb/typec/mux/intel_pmc_mux.c
> @@ -151,13 +151,14 @@ struct pmc_usb {
>  	u8 num_ports;
>  	struct device *dev;
>  	struct intel_scu_ipc_dev *ipc;
> -	struct pmc_usb_port *port;
>  	struct acpi_device *iom_adev;
>  	void __iomem *iom_base;
>  	u32 iom_port_status_offset;
>  	u8 iom_port_status_size;
>  
>  	struct dentry *dentry;
> +
> +	struct pmc_usb_port port[] __counted_by(num_ports);
>  };
>  
>  static struct dentry *pmc_mux_debugfs_root;
> @@ -731,27 +732,26 @@ static int pmc_usb_probe(struct platform_device *pdev)
>  {
>  	struct fwnode_handle *fwnode = NULL;
>  	struct pmc_usb *pmc;
> +	u8 num_ports;
>  	int i = 0;
>  	int ret;
>  
> -	pmc = devm_kzalloc(&pdev->dev, sizeof(*pmc), GFP_KERNEL);
> -	if (!pmc)
> -		return -ENOMEM;
> -
>  	device_for_each_child_node(&pdev->dev, fwnode)
> -		pmc->num_ports++;
> +		num_ports++;
>  
>  	/* The IOM microcontroller has a limitation of max 4 ports. */
> -	if (pmc->num_ports > 4) {
> +	if (num_ports > 4) {
>  		dev_err(&pdev->dev, "driver limited to 4 ports\n");
>  		return -ERANGE;
>  	}
>  
> -	pmc->port = devm_kcalloc(&pdev->dev, pmc->num_ports,
> -				 sizeof(struct pmc_usb_port), GFP_KERNEL);
> -	if (!pmc->port)
> +	pmc = devm_kzalloc(&pdev->dev, struct_size(pmc, port, num_ports),
> +			GFP_KERNEL);

One line is enough for that.

> +	if (!pmc)
>  		return -ENOMEM;
>  
> +	pmc->num_ports = num_ports;
> +
>  	pmc->ipc = devm_intel_scu_ipc_dev_get(&pdev->dev);
>  	if (!pmc->ipc)
>  		return -EPROBE_DEFER;
> -- 
> 2.53.0

thanks,

-- 
heikki