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Subject[PATCH] 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>
---
drivers/char/hpet.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index 9bffcd37cc7b..d0ad85900b79 100644
--- 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;
--
2.20.1
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