2019-01-04 21:40:39

by Gustavo A. R. Silva

Subject: [PATCH] serial: max310x: 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/tty/serial/max310x.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c
index 4f479841769a..1d700a8ab517 100644
--- a/drivers/tty/serial/max310x.c
+++ b/drivers/tty/serial/max310x.c
@@ -1197,8 +1197,7 @@ static int max310x_probe(struct device *dev, struct max310x_devtype *devtype,
return PTR_ERR(regmap);

/* Alloc port structure */
- s = devm_kzalloc(dev, sizeof(*s) +
- sizeof(struct max310x_one) * devtype->nr, GFP_KERNEL);
+ s = devm_kzalloc(dev, struct_size(s, p, devtype->nr), GFP_KERNEL);
if (!s) {
dev_err(dev, "Error allocating port structure\n");
return -ENOMEM;
--
2.20.1

2019-03-07 11:04:24

by Jan Kundrát

Subject: Re: [PATCH] serial: max310x: Use struct_size() in devm_kzalloc()

On pátek 4. ledna 2019 22:39:13 CET, Gustavo A. R. Silva 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/tty/serial/max310x.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c
> index 4f479841769a..1d700a8ab517 100644
> --- a/drivers/tty/serial/max310x.c
> +++ b/drivers/tty/serial/max310x.c
> @@ -1197,8 +1197,7 @@ static int max310x_probe(struct device
> *dev, struct max310x_devtype *devtype,
> return PTR_ERR(regmap);
>
> /* Alloc port structure */
> - s = devm_kzalloc(dev, sizeof(*s) +
> - sizeof(struct max310x_one) * devtype->nr, GFP_KERNEL);
> + s = devm_kzalloc(dev, struct_size(s, p, devtype->nr), GFP_KERNEL);
> if (!s) {
> dev_err(dev, "Error allocating port structure\n");
> return -ENOMEM;

Reviewed-by: Jan Kundrát <[email protected]>
Tested-by: Jan Kundrát <[email protected]>