hpet: Use struct_size() in 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 = kzalloc(size, 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);

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

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index 9bffcd37cc7bd65b93fbac59f996b62d118d084f..d0ad85900b7948e68d1654a410f2c5dde6e6511e 100644 (file)
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -842,7 +842,6 @@ int hpet_alloc(struct hpet_data *hdp)
        struct hpet_dev *devp;
        u32 i, ntimer;
        struct hpets *hpetp;
-       size_t siz;
        struct hpet __iomem *hpet;
        static struct hpets *last;
        unsigned long period;
@@ -860,10 +859,8 @@ int hpet_alloc(struct hpet_data *hdp)
                return 0;
        }
 
-       siz = sizeof(struct hpets) + ((hdp->hd_nirqs - 1) *
-                                     sizeof(struct hpet_dev));
-
-       hpetp = kzalloc(siz, GFP_KERNEL);
+       hpetp = kzalloc(struct_size(hpetp, hp_dev, hdp->hd_nirqs - 1),
+                       GFP_KERNEL);
 
        if (!hpetp)
                return -ENOMEM;