[PATCH] pinctrl: sirf: atlas7: use struct_size() in devm_kzalloc()

[PATCH] pinctrl: sirf: atlas7: use struct_size() in devm_kzalloc()

[Gustavo A. R. Silva]

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct foo {
    int stuff;
    void *entry[];
};

instance = devm_kzalloc(dev, sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = devm_kzalloc(dev, struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/pinctrl/sirf/pinctrl-atlas7.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pinctrl/sirf/pinctrl-atlas7.c b/drivers/pinctrl/sirf/pinctrl-atlas7.c
index 4ba171827428..8a0eee044264 100644
--- a/drivers/pinctrl/sirf/pinctrl-atlas7.c
+++ b/drivers/pinctrl/sirf/pinctrl-atlas7.c
@@ -6007,8 +6007,8 @@ static int atlas7_gpio_probe(struct platform_device *pdev)
 	}
 
 	/* retrieve gpio descriptor data */
-	a7gc = devm_kzalloc(&pdev->dev, sizeof(*a7gc) +
-			sizeof(struct atlas7_gpio_bank) * nbank, GFP_KERNEL);
+	a7gc = devm_kzalloc(&pdev->dev, struct_size(a7gc, banks, nbank),
+			    GFP_KERNEL);
 	if (!a7gc)
 		return -ENOMEM;
 
-- 
2.20.1


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Re: [PATCH] pinctrl: sirf: atlas7: use struct_size() in devm_kzalloc()

[Linus Walleij]

On Fri, Jan 4, 2019 at 10:35 PM Gustavo A. R. Silva
<gustavo@embeddedor.com> wrote:

> One of the more common cases of allocation size calculations is finding
> the size of a structure that has a zero-sized array at the end, along
> with memory for some number of elements for that array. For example:
>
> struct foo {
>     int stuff;
>     void *entry[];
> };
>
> instance = devm_kzalloc(dev, sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);
>
> Instead of leaving these open-coded and prone to type mistakes, we can
> now use the new struct_size() helper:
>
> instance = devm_kzalloc(dev, struct_size(instance, entry, count), GFP_KERNEL);
>
> This code was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Patch applied.

Yours,
Linus Walleij

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