Re: [PATCH] cpufreq: e_powersaver: Use struct_size() in kzalloc()

Viresh Kumar
2019-01-08T05:00:56Z

On 07-01-19, 11:33, 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 = kzalloc(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 = kzalloc(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/cpufreq/e_powersaver.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/cpufreq/e_powersaver.c b/drivers/cpufreq/e_powersaver.c
> index 60bea302abbe..2d3ef208dd70 100644
> --- a/drivers/cpufreq/e_powersaver.c
> +++ b/drivers/cpufreq/e_powersaver.c
> @@ -323,9 +323,8 @@ static int eps_cpu_init(struct cpufreq_policy *policy)
> states = 2;
>
> /* Allocate private data and frequency table for current cpu */
> - centaur = kzalloc(sizeof(*centaur)
> - + (states + 1) * sizeof(struct cpufreq_frequency_table),
> - GFP_KERNEL);
> + centaur = kzalloc(struct_size(centaur, freq_table, states + 1),
> + GFP_KERNEL);
> if (!centaur)
> return -ENOMEM;
> eps_cpu[0] = centaur;

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

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viresh