RE: [PATCH] regulator: da9062: Use struct_size() in devm_kzalloc()

From: Steve Twiss
Date: Mon Feb 25 2019 - 08:13:39 EST


Hi Gustavo,

On 23 February 2019 01:55, Gustavo A. R. Silva wrote:

> Subject: [PATCH] regulator: da9062: 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;
> struct boo entry[];
> };
>
> size = sizeof(struct foo) + count * sizeof(struct boo);
> instance = alloc(size, GFP_KERNEL)
>
> Instead of leaving these open-coded and prone to type mistakes, we can
> now use the new struct_size() helper:

Acked-by: Steve Twiss <stwiss.opensource@xxxxxxxxxxx>

Thanks,

Regards,
Steve

>
> instance = alloc(struct_size(instance, entry, count), GFP_KERNEL)
>
> Notice that, in this case, variable size is not necessary, hence it is
> removed.
>
> This code was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
> ---
> drivers/regulator/da9062-regulator.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/regulator/da9062-regulator.c b/drivers/regulator/da9062-
> regulator.c
> index 4c5d6ad853f8..b064d8a19d4c 100644
> --- a/drivers/regulator/da9062-regulator.c
> +++ b/drivers/regulator/da9062-regulator.c
> @@ -992,7 +992,6 @@ static int da9062_regulator_probe(struct platform_device
> *pdev)
> struct regulator_config config = { };
> const struct da9062_regulator_info *rinfo;
> int irq, n, ret;
> - size_t size;
> int max_regulators;
>
> switch (chip->chip_type) {
> @@ -1010,9 +1009,8 @@ static int da9062_regulator_probe(struct
> platform_device *pdev)
> }
>
> /* Allocate memory required by usable regulators */
> - size = sizeof(struct da9062_regulators) +
> - max_regulators * sizeof(struct da9062_regulator);
> - regulators = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
> + regulators = devm_kzalloc(&pdev->dev, struct_size(regulators, regulator,
> + max_regulators), GFP_KERNEL);
> if (!regulators)
> return -ENOMEM;
>
> --
> 2.20.1