afs: Use struct_size() in kzalloc()

GustavoARSilva · dhowells · commit c2b8bd49d35a · 2019-01-10T17:12:05.000Z
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 &lt;gustavo@embeddedor.com&gt;
Signed-off-by: David Howells &lt;dhowells@redhat.com&gt;
diff --git a/fs/afs/server_list.c b/fs/afs/server_list.c
@@ -42,9 +42,7 @@ struct afs_server_list *afs_alloc_server_list(struct afs_cell *cell,
 		if (vldb->fs_mask[i] & type_mask)
 			nr_servers++;
 
-	slist = kzalloc(sizeof(struct afs_server_list) +
-			sizeof(struct afs_server_entry) * nr_servers,
-			GFP_KERNEL);
+	slist = kzalloc(struct_size(slist, servers, nr_servers), GFP_KERNEL);
 	if (!slist)
 		goto error;
 
