[PATCH net-next] cxgb4: cxgb4_tc_u32: use struct_size() in kvzalloc()

[PATCH net-next] cxgb4: cxgb4_tc_u32: 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/cxgb4_tc_u32.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_u32.c b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_u32.c
index c7d2b4dc7568..02fc63fa7f25 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_u32.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_u32.c
@@ -444,8 +444,7 @@ struct cxgb4_tc_u32_table *cxgb4_init_tc_u32(struct adapter *adap)
 	if (!max_tids)
 		return NULL;
 
-	t = kvzalloc(sizeof(*t) +
-			 (max_tids * sizeof(struct cxgb4_link)), GFP_KERNEL);
+	t = kvzalloc(struct_size(t, table, max_tids), GFP_KERNEL);
 	if (!t)
 		return NULL;
 
-- 
2.20.1

Re: [PATCH net-next] cxgb4: cxgb4_tc_u32: use struct_size() in kvzalloc()

[David Miller]

From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Tue, 29 Jan 2019 11:05:23 -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, thanks.

Re: [PATCH net-next] cxgb4: cxgb4_tc_u32: use struct_size() in kvzalloc()

[Gustavo A. R. Silva]

On 1/29/19 12:57 PM, David Miller wrote:

>>
>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> 
> Applied, thanks.
> 

Thanks, Dave.

--
Gustavo