eeprom: at24: 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 = devm_kzalloc(dev, size, 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);

Notice that, in this case, variable at24_size is not necessary, hence it is removed.

This code was detected with the help of Coccinelle.

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 drivers/misc/eeprom/at24.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

drivers/misc/eeprom/at24.c +2 -4

index ba8e73812644..78ba6b1917a8 100644
@@ -568,7 +568,6 @@ static int at24_probe(struct i2c_client *client)
        unsigned int i, num_addresses;
        struct at24_data *at24;
        struct regmap *regmap;
-       size_t at24_size;
        bool writable;
        u8 test_byte;
        int err;

@@ -652,8 +651,8 @@ static int at24_probe(struct i2c_client *client)
        if (IS_ERR(regmap))
                return PTR_ERR(regmap);
 
-       at24_size = sizeof(*at24) + num_addresses * sizeof(struct at24_client);
-       at24 = devm_kzalloc(dev, at24_size, GFP_KERNEL);
+       at24 = devm_kzalloc(dev, struct_size(at24, client, num_addresses),
+                           GFP_KERNEL);
        if (!at24)
                return -ENOMEM;
 
--

2.21.0