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

Gustavo A. R. Silva
2019-01-07T17:33:43Z

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;
--
2.20.1