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nfp: flower: cmsg: use struct_size() helper

PATCH Applied Gustavo A. R. Silva 3 participants 3 messages Feb 8, 2019 – Feb 9, 2019

Subsystems (3)
Networking Network drivers Netronome Ethernet drivers
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Gustavo A. R. Silva

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#0 lore raw

PATCH 1/1 nfp: flower: cmsg: use struct_size() helper

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 <[email protected]>
---
 drivers/net/ethernet/netronome/nfp/flower/cmsg.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)
drivers/net/ethernet/netronome/nfp/flower/cmsg.c +2 -4
index 56b22ea32474..cf9e1118ee8f 100644
@@ -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;
Signature · 1 line
2.20.1
Acked-by on v1 1/1
#1 lore raw
Quoted 15 lines · 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:

Quoted 8 lines

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 <[email protected]>
Acked-by Jakub Kicinski <[email protected]>
maintainer Applied
#2 lore raw
In reply to Gustavo A. R. Silva

From: "Gustavo A. R. Silva" <[email protected]>
Date: Thu, 7 Feb 2019 21:47:25 -0600

Quoted 15 lines

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:

Quoted 8 lines

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 <[email protected]>

Applied.