Input: applespi - use struct_size() helper

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 touchpad_protocol {
	...
        struct tp_finger        fingers[0];
};

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.

So, replace the following form:

sizeof(*tp) + tp->number_of_fingers * sizeof(tp->fingers[0]);

with:

struct_size(tp, fingers, tp->number_of_fingers)

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/keyboard/applespi.c b/drivers/input/keyboard/applespi.c
index acf34a5ff571225d463f4b147e6b6aa7ca36111c..584289b67fb3cbccc20f9a26200c624fea468ef9 100644 (file)
--- a/drivers/input/keyboard/applespi.c
+++ b/drivers/input/keyboard/applespi.c
@@ -1494,8 +1494,7 @@ static void applespi_got_data(struct applespi_data *applespi)
                size_t tp_len;
 
                tp = &message->touchpad;
-               tp_len = sizeof(*tp) +
-                        tp->number_of_fingers * sizeof(tp->fingers[0]);
+               tp_len = struct_size(tp, fingers, tp->number_of_fingers);
 
                if (le16_to_cpu(message->length) + 2 != tp_len) {
                        dev_warn_ratelimited(&applespi->spi->dev,