[PATCH net-next] sctp: deduplicate identical skb_checksum_ops

From: Matteo Croce
Date: Wed May 29 2019 - 11:43:15 EST


The same skb_checksum_ops struct is defined twice in two different places,
leading to code duplication. Declare it as a global variable into a common
header instead of allocating it on the stack on each function call.
bloat-o-meter reports a slight code shrink.

add/remove: 1/1 grow/shrink: 0/10 up/down: 128/-1282 (-1154)
Function old new delta
sctp_csum_ops - 128 +128
crc32c_csum_ops 16 - -16
sctp_rcv 6616 6583 -33
sctp_packet_pack 4542 4504 -38
nf_conntrack_sctp_packet 4980 4926 -54
execute_masked_set_action 6453 6389 -64
tcf_csum_sctp 575 428 -147
sctp_gso_segment 1292 1126 -166
sctp_csum_check 579 412 -167
sctp_snat_handler 957 772 -185
sctp_dnat_handler 1321 1132 -189
l4proto_manip_pkt 2536 2313 -223
Total: Before=359297613, After=359296459, chg -0.00%

Reviewed-by: Xin Long <lucien.xin@xxxxxxxxx>
Signed-off-by: Matteo Croce <mcroce@xxxxxxxxxx>
---
include/net/sctp/checksum.h | 12 +++++++-----
net/sctp/offload.c | 7 +------
2 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/include/net/sctp/checksum.h b/include/net/sctp/checksum.h
index 314699333bec..5a9bb09f32b6 100644
--- a/include/net/sctp/checksum.h
+++ b/include/net/sctp/checksum.h
@@ -43,19 +43,21 @@ static inline __wsum sctp_csum_combine(__wsum csum, __wsum csum2,
(__force __u32)csum2, len);
}

+static const struct skb_checksum_ops sctp_csum_ops = {
+ .update = sctp_csum_update,
+ .combine = sctp_csum_combine,
+};
+
static inline __le32 sctp_compute_cksum(const struct sk_buff *skb,
unsigned int offset)
{
struct sctphdr *sh = (struct sctphdr *)(skb->data + offset);
- const struct skb_checksum_ops ops = {
- .update = sctp_csum_update,
- .combine = sctp_csum_combine,
- };
__le32 old = sh->checksum;
__wsum new;

sh->checksum = 0;
- new = ~__skb_checksum(skb, offset, skb->len - offset, ~(__wsum)0, &ops);
+ new = ~__skb_checksum(skb, offset, skb->len - offset, ~(__wsum)0,
+ &sctp_csum_ops);
sh->checksum = old;

return cpu_to_le32((__force __u32)new);
diff --git a/net/sctp/offload.c b/net/sctp/offload.c
index edfcf16e704c..dac46dfadab5 100644
--- a/net/sctp/offload.c
+++ b/net/sctp/offload.c
@@ -103,11 +103,6 @@ static const struct net_offload sctp6_offload = {
},
};

-static const struct skb_checksum_ops crc32c_csum_ops = {
- .update = sctp_csum_update,
- .combine = sctp_csum_combine,
-};
-
int __init sctp_offload_init(void)
{
int ret;
@@ -120,7 +115,7 @@ int __init sctp_offload_init(void)
if (ret)
goto ipv4;

- crc32c_csum_stub = &crc32c_csum_ops;
+ crc32c_csum_stub = &sctp_csum_ops;
return ret;

ipv4:
--
2.21.0