ipv6: Optimize ipv6_change_dsfield().

Do not convert endian back and forth.
If the caller uses contant "mask" argument (and most callers do),
we can omit runtime endian conversion here.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/dsfield.h b/include/net/dsfield.h
index 8a8d4e06900d8824ba4a892c5f29f9c40525f0e0..e1ad903a8d6a0ff2a93106a9a3e430d4f0089558 100644 (file)
--- a/include/net/dsfield.h
+++ b/include/net/dsfield.h
@@ -43,11 +43,9 @@ static inline void ipv4_change_dsfield(struct iphdr *iph,__u8 mask,
 static inline void ipv6_change_dsfield(struct ipv6hdr *ipv6h,__u8 mask,
     __u8 value)
 {
-        __u16 tmp;
+       __be16 *p = (__force __be16 *)ipv6h;
 
-       tmp = ntohs(*(__be16 *) ipv6h);
-       tmp = (tmp & ((mask << 4) | 0xf00f)) | (value << 4);
-       *(__be16 *) ipv6h = htons(tmp);
+       *p = (*p & htons((((u16)mask << 4) | 0xf00f))) | htons((u16)value << 4);
 }