[PATCH net-next] cxgb4: sched: use struct_size() in kvzalloc()

[PATCH net-next] cxgb4: sched: use struct_size() in kvzalloc()

[Gustavo A. R. Silva]

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[];
};

instance = kvzalloc(sizeof(struct foo) + count * sizeof(struct boo), GFP_KERNEL);

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

instance = kvzalloc(struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/net/ethernet/chelsio/cxgb4/sched.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb4/sched.c b/drivers/net/ethernet/chelsio/cxgb4/sched.c
index 52edb688942b..ba6c153ee45c 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/sched.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/sched.c
@@ -478,7 +478,7 @@ struct sched_table *t4_init_sched(unsigned int sched_size)
 	struct sched_table *s;
 	unsigned int i;
 
-	s = kvzalloc(sizeof(*s) + sched_size * sizeof(struct sched_class), GFP_KERNEL);
+	s = kvzalloc(struct_size(s, tab, sched_size), GFP_KERNEL);
 	if (!s)
 		return NULL;
 
-- 
2.20.1

Re: [PATCH net-next] cxgb4: sched: use struct_size() in kvzalloc()

[David Miller]

From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Wed, 30 Jan 2019 18:23:14 -0600

> 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[];
> };
> 
> instance = kvzalloc(sizeof(struct foo) + count * sizeof(struct boo), GFP_KERNEL);
> 
> Instead of leaving these open-coded and prone to type mistakes, we can now
> use the new struct_size() helper:
> 
> instance = kvzalloc(struct_size(instance, entry, count), GFP_KERNEL);
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Applied.