* [PATCH net-next] nfp: flower: cmsg: use struct_size() helper
@ 2019-02-08 3:47 Gustavo A. R. Silva
2019-02-08 15:51 ` Jakub Kicinski
2019-02-09 6:58 ` David Miller
0 siblings, 2 replies; 3+ messages in thread
From: Gustavo A. R. Silva @ 2019-02-08 3:47 UTC (permalink / raw)
To: Jakub Kicinski, David S. Miller
Cc: oss-drivers, netdev, linux-kernel, 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;
void *entry[];
};
size = sizeof(struct foo) + count * sizeof(void *);
instance = alloc(size, GFP_KERNEL);
Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:
instance = alloc(struct_size(instance, entry, count), GFP_KERNEL);
Notice that, in this case, variable size 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/net/ethernet/netronome/nfp/flower/cmsg.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ethernet/netronome/nfp/flower/cmsg.c b/drivers/net/ethernet/netronome/nfp/flower/cmsg.c
index 56b22ea32474..cf9e1118ee8f 100644
--- a/drivers/net/ethernet/netronome/nfp/flower/cmsg.c
+++ b/drivers/net/ethernet/netronome/nfp/flower/cmsg.c
@@ -45,11 +45,9 @@ nfp_flower_cmsg_mac_repr_start(struct nfp_app *app, unsigned int num_ports)
{
struct nfp_flower_cmsg_mac_repr *msg;
struct sk_buff *skb;
- unsigned int size;
- size = sizeof(*msg) + num_ports * sizeof(msg->ports[0]);
- skb = nfp_flower_cmsg_alloc(app, size, NFP_FLOWER_CMSG_TYPE_MAC_REPR,
- GFP_KERNEL);
+ skb = nfp_flower_cmsg_alloc(app, struct_size(msg, ports, num_ports),
+ NFP_FLOWER_CMSG_TYPE_MAC_REPR, GFP_KERNEL);
if (!skb)
return NULL;
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH net-next] nfp: flower: cmsg: use struct_size() helper
2019-02-08 3:47 [PATCH net-next] nfp: flower: cmsg: use struct_size() helper Gustavo A. R. Silva
@ 2019-02-08 15:51 ` Jakub Kicinski
2019-02-09 6:58 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: Jakub Kicinski @ 2019-02-08 15:51 UTC (permalink / raw)
To: Gustavo A. R. Silva; +Cc: David S. Miller, oss-drivers, netdev, linux-kernel
On Thu, 7 Feb 2019 21:47:25 -0600, Gustavo A. R. Silva wrote:
> 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[];
> };
>
> size = sizeof(struct foo) + count * sizeof(void *);
> instance = alloc(size, GFP_KERNEL);
>
> Instead of leaving these open-coded and prone to type mistakes, we can
> now use the new struct_size() helper:
>
> instance = alloc(struct_size(instance, entry, count), GFP_KERNEL);
>
> Notice that, in this case, variable size 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>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH net-next] nfp: flower: cmsg: use struct_size() helper
2019-02-08 3:47 [PATCH net-next] nfp: flower: cmsg: use struct_size() helper Gustavo A. R. Silva
2019-02-08 15:51 ` Jakub Kicinski
@ 2019-02-09 6:58 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2019-02-09 6:58 UTC (permalink / raw)
To: gustavo; +Cc: jakub.kicinski, oss-drivers, netdev, linux-kernel
From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Thu, 7 Feb 2019 21:47:25 -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;
> void *entry[];
> };
>
> size = sizeof(struct foo) + count * sizeof(void *);
> instance = alloc(size, GFP_KERNEL);
>
> Instead of leaving these open-coded and prone to type mistakes, we can
> now use the new struct_size() helper:
>
> instance = alloc(struct_size(instance, entry, count), GFP_KERNEL);
>
> Notice that, in this case, variable size 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>
Applied.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-02-08 3:47 [PATCH net-next] nfp: flower: cmsg: use struct_size() helper Gustavo A. R. Silva
2019-02-08 15:51 ` Jakub Kicinski
2019-02-09 6:58 ` David Miller
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