[PATCH] gpio: dwapb: reduce allocation to single kzalloc

[PATCH] gpio: dwapb: reduce allocation to single kzalloc

[Rosen Penev]

Instead of kzalloc + kcalloc, Combine the two using a flexible array
member.

Allows using __counted_by for extra runtime analysis. Move counting
variable to right after allocation as required by __counted_by.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/gpio/gpio-dwapb.c | 19 +++++--------------
 1 file changed, 5 insertions(+), 14 deletions(-)

diff --git a/drivers/gpio/gpio-dwapb.c b/drivers/gpio/gpio-dwapb.c
index 4986c465c9a8..15cebc8b5d66 100644
--- a/drivers/gpio/gpio-dwapb.c
+++ b/drivers/gpio/gpio-dwapb.c
@@ -75,8 +75,8 @@ struct dwapb_port_property {
 };
 
 struct dwapb_platform_data {
-	struct dwapb_port_property *properties;
 	unsigned int nports;
+	struct dwapb_port_property properties[] __counted_by(nports);
 };
 
 /* Store GPIO context across system-wide suspend/resume transitions */
@@ -114,11 +114,11 @@ static inline struct dwapb_gpio *to_dwapb_gpio(struct gpio_chip *gc)
 struct dwapb_gpio {
 	struct	device		*dev;
 	void __iomem		*regs;
-	struct dwapb_gpio_port	*ports;
 	unsigned int		nr_ports;
 	unsigned int		flags;
 	struct reset_control	*rst;
 	struct clk_bulk_data	clks[DWAPB_NR_CLOCKS];
+	struct dwapb_gpio_port	ports[] __counted_by(nr_ports);
 };
 
 static inline u32 gpio_reg_v2_convert(unsigned int offset)
@@ -585,14 +585,10 @@ static struct dwapb_platform_data *dwapb_gpio_get_pdata(struct device *dev)
 	if (nports == 0)
 		return ERR_PTR(-ENODEV);
 
-	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
+	pdata = devm_kzalloc(dev, struct_size(pdata, properties, nports), GFP_KERNEL);
 	if (!pdata)
 		return ERR_PTR(-ENOMEM);
 
-	pdata->properties = devm_kcalloc(dev, nports, sizeof(*pp), GFP_KERNEL);
-	if (!pdata->properties)
-		return ERR_PTR(-ENOMEM);
-
 	pdata->nports = nports;
 
 	i = 0;
@@ -714,22 +710,17 @@ static int dwapb_gpio_probe(struct platform_device *pdev)
 	if (IS_ERR(pdata))
 		return PTR_ERR(pdata);
 
-	gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
+	gpio = devm_kzalloc(&pdev->dev, struct_size(gpio, ports, pdata->nports), GFP_KERNEL);
 	if (!gpio)
 		return -ENOMEM;
 
-	gpio->dev = &pdev->dev;
 	gpio->nr_ports = pdata->nports;
+	gpio->dev = &pdev->dev;
 
 	err = dwapb_get_reset(gpio);
 	if (err)
 		return err;
 
-	gpio->ports = devm_kcalloc(&pdev->dev, gpio->nr_ports,
-				   sizeof(*gpio->ports), GFP_KERNEL);
-	if (!gpio->ports)
-		return -ENOMEM;
-
 	gpio->regs = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(gpio->regs))
 		return PTR_ERR(gpio->regs);
-- 
2.53.0

Re: [PATCH] gpio: dwapb: reduce allocation to single kzalloc

[Linus Walleij]

On Fri, Mar 20, 2026 at 1:53 AM Rosen Penev <rosenp@gmail.com> wrote:

> Instead of kzalloc + kcalloc, Combine the two using a flexible array
> member.
>
> Allows using __counted_by for extra runtime analysis. Move counting
> variable to right after allocation as required by __counted_by.
>
> Signed-off-by: Rosen Penev <rosenp@gmail.com>

Reviewed-by: Linus Walleij <linusw@kernel.org>

Yours,
Linus Walleij

Re: [PATCH] gpio: dwapb: reduce allocation to single kzalloc

[Bartosz Golaszewski]

On Thu, 19 Mar 2026 17:53:38 -0700, Rosen Penev wrote:
> Instead of kzalloc + kcalloc, Combine the two using a flexible array
> member.
> 
> Allows using __counted_by for extra runtime analysis. Move counting
> variable to right after allocation as required by __counted_by.
> 
> 
> [...]

Applied, thanks!

[1/1] gpio: dwapb: reduce allocation to single kzalloc
      https://git.kernel.org/brgl/c/9a5bf2f53b76b1619c602f9e751fe4c0e64713ca

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>