net: usb: cdc-phonet: use struct_size() in alloc_netdev()

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 = alloc(sizeof(struct foo) + count * sizeof(void *));

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = alloc(struct_size(instance, entry, count));

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/usb/cdc-phonet.c b/drivers/net/usb/cdc-phonet.c
index 78b16eb9e58c8ddb93e35ed965f00b1f173f3804..63aaae4879953f466efd8d48c4f334f2325cbca6 100644 (file)
--- a/drivers/net/usb/cdc-phonet.c
+++ b/drivers/net/usb/cdc-phonet.c
@@ -361,8 +361,8 @@ static int usbpn_probe(struct usb_interface *intf, const struct usb_device_id *i
        else
                return -EINVAL;
 
-       dev = alloc_netdev(sizeof(*pnd) + sizeof(pnd->urbs[0]) * rxq_size,
-                          ifname, NET_NAME_UNKNOWN, usbpn_setup);
+       dev = alloc_netdev(struct_size(pnd, urbs, rxq_size), ifname,
+                          NET_NAME_UNKNOWN, usbpn_setup);
        if (!dev)
                return -ENOMEM;