[PATCH 3/5] net: core: Use FIELD_SIZEOF directly instead of reimplementing its function

[zhong jiang <zhongjiang@huawei.com>]

FIELD_SIZEOF is defined as a macro to calculate the specified value. Therefore,
We prefer to use the macro rather than calculating its value.

Signed-off-by: zhong jiang <zhongjiang@huawei.com>
---
 net/core/flow_dissector.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 5c5dd74..aeac884 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -423,8 +423,8 @@ __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
 	offset += sizeof(struct gre_base_hdr);
 
 	if (hdr->flags & GRE_CSUM)
-		offset += sizeof(((struct gre_full_hdr *) 0)->csum) +
-			  sizeof(((struct gre_full_hdr *) 0)->reserved1);
+		offset += FIELD_SIZEOF(struct gre_full_hdr, csum) +
+			  FIELD_SIZEOF(struct gre_full_hdr, reserved1);
 
 	if (hdr->flags & GRE_KEY) {
 		const __be32 *keyid;
@@ -446,11 +446,11 @@ __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
 			else
 				key_keyid->keyid = *keyid & GRE_PPTP_KEY_MASK;
 		}
-		offset += sizeof(((struct gre_full_hdr *) 0)->key);
+		offset += FIELD_SIZEOF(struct gre_full_hdr, key);
 	}
 
 	if (hdr->flags & GRE_SEQ)
-		offset += sizeof(((struct pptp_gre_header *) 0)->seq);
+		offset += FIELD_SIZEOF(struct pptp_gre_header, seq);
 
 	if (gre_ver == 0) {
 		if (*p_proto == htons(ETH_P_TEB)) {
@@ -477,7 +477,7 @@ __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
 		u8 *ppp_hdr;
 
 		if (hdr->flags & GRE_ACK)
-			offset += sizeof(((struct pptp_gre_header *) 0)->ack);
+			offset += FIELD_SIZEOF(struct pptp_gre_header, ack);
 
 		ppp_hdr = __skb_header_pointer(skb, *p_nhoff + offset,
 					       sizeof(_ppp_hdr),
-- 
1.7.12.4