2019-01-04 19:00:40

by Gustavo A. R. Silva

Subject: [PATCH] mtd: rawnand: sunxi: Use struct_size() in devm_kzalloc()

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 <[email protected]>
---
drivers/mtd/nand/raw/sunxi_nand.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/mtd/nand/raw/sunxi_nand.c b/drivers/mtd/nand/raw/sunxi_nand.c
index e828ee50a201..f66fffe663bf 100644
--- a/drivers/mtd/nand/raw/sunxi_nand.c
+++ b/drivers/mtd/nand/raw/sunxi_nand.c
@@ -1870,10 +1870,7 @@ static int sunxi_nand_chip_init(struct device *dev, struct sunxi_nfc *nfc,
return -EINVAL;
}

- chip = devm_kzalloc(dev,
- sizeof(*chip) +
- (nsels * sizeof(struct sunxi_nand_chip_sel)),
- GFP_KERNEL);
+ chip = devm_kzalloc(dev, struct_size(chip, sels, nsels), GFP_KERNEL);
if (!chip) {
dev_err(dev, "could not allocate chip\n");
return -ENOMEM;
--
2.20.1

2019-01-04 19:05:37

by Boris Brezillon

Subject: Re: [PATCH] mtd: rawnand: sunxi: Use struct_size() in devm_kzalloc()

Hi Gustavo,

On Fri, 4 Jan 2019 11:26:37 -0600
"Gustavo A. R. Silva" <[email protected]> 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 <[email protected]>
> ---
> drivers/mtd/nand/raw/sunxi_nand.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/sunxi_nand.c b/drivers/mtd/nand/raw/sunxi_nand.c
> index e828ee50a201..f66fffe663bf 100644
> --- a/drivers/mtd/nand/raw/sunxi_nand.c
> +++ b/drivers/mtd/nand/raw/sunxi_nand.c
> @@ -1870,10 +1870,7 @@ static int sunxi_nand_chip_init(struct device *dev, struct sunxi_nfc *nfc,
> return -EINVAL;
> }
>
> - chip = devm_kzalloc(dev,
> - sizeof(*chip) +
> - (nsels * sizeof(struct sunxi_nand_chip_sel)),
> - GFP_KERNEL);
> + chip = devm_kzalloc(dev, struct_size(chip, sels, nsels), GFP_KERNEL);
> if (!chip) {
> dev_err(dev, "could not allocate chip\n");
> return -ENOMEM;

I posted the same patch a few days back [1].

[1]http://patchwork.ozlabs.org/patch/1013855/

2019-01-04 19:05:50

by Gustavo A. R. Silva

Subject: Re: [PATCH] mtd: rawnand: sunxi: Use struct_size() in devm_kzalloc()

Hey Boris,

On 1/4/19 12:14 PM, Boris Brezillon wrote:

>
> I posted the same patch a few days back [1].
>
> [1]http://patchwork.ozlabs.org/patch/1013855/
>

Oh, that's great.

It's good to see people adopting the struct_size helper. :)

Happy new year.

Thanks
--
Gustavo