ip: IP cmsg cleanup

Move the IP_CMSG_* constants from ip_sockglue.c to inet_sock.h so that
they can be referenced in other source files.

Restructure ip_cmsg_recv to not go through flags using shift, check
for flags by 'and'. This eliminates both the shift and a conditional
per flag check.
Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/inet_sock.h

@@ -16,7 +16,7 @@
 #ifndef _INET_SOCK_H
 #define _INET_SOCK_H
 
-
+#include <linux/bitops.h>
 #include <linux/kmemcheck.h>
 #include <linux/string.h>
 #include <linux/types.h>
@@ -195,6 +195,15 @@ struct inet_sock {
 #define IPCORK_OPT	1	/* ip-options has been held in ipcork.opt */
 #define IPCORK_ALLFRAG	2	/* always fragment (for ipv6 for now) */
 
+/* cmsg flags for inet */
+#define IP_CMSG_PKTINFO		BIT(0)
+#define IP_CMSG_TTL		BIT(1)
+#define IP_CMSG_TOS		BIT(2)
+#define IP_CMSG_RECVOPTS	BIT(3)
+#define IP_CMSG_RETOPTS		BIT(4)
+#define IP_CMSG_PASSSEC		BIT(5)
+#define IP_CMSG_ORIGDSTADDR	BIT(6)
+
 static inline struct inet_sock *inet_sk(const struct sock *sk)
 {
 	return (struct inet_sock *)sk;

net/ipv4/ip_sockglue.c

@@ -45,14 +45,6 @@
 #include <linux/errqueue.h>
 #include <asm/uaccess.h>
 
-#define IP_CMSG_PKTINFO		1
-#define IP_CMSG_TTL		2
-#define IP_CMSG_TOS		4
-#define IP_CMSG_RECVOPTS	8
-#define IP_CMSG_RETOPTS		16
-#define IP_CMSG_PASSSEC		32
-#define IP_CMSG_ORIGDSTADDR     64
-
 /*
  *	SOL_IP control messages.
  */
@@ -150,37 +142,55 @@ void ip_cmsg_recv(struct msghdr *msg, struct sk_buff *skb)
 	unsigned int flags = inet->cmsg_flags;
 
 	/* Ordered by supposed usage frequency */
-	if (flags & 1)
+	if (flags & IP_CMSG_PKTINFO) {
 		ip_cmsg_recv_pktinfo(msg, skb);
-	if ((flags >>= 1) == 0)
+
+		flags &= ~IP_CMSG_PKTINFO;
+		if (!flags)
 			return;
+	}
 
-	if (flags & 1)
+	if (flags & IP_CMSG_TTL) {
 		ip_cmsg_recv_ttl(msg, skb);
-	if ((flags >>= 1) == 0)
+
+		flags &= ~IP_CMSG_TTL;
+		if (!flags)
 			return;
+	}
 
-	if (flags & 1)
+	if (flags & IP_CMSG_TOS) {
 		ip_cmsg_recv_tos(msg, skb);
-	if ((flags >>= 1) == 0)
+
+		flags &= ~IP_CMSG_TOS;
+		if (!flags)
 			return;
+	}
 
-	if (flags & 1)
+	if (flags & IP_CMSG_RECVOPTS) {
 		ip_cmsg_recv_opts(msg, skb);
-	if ((flags >>= 1) == 0)
+
+		flags &= ~IP_CMSG_RECVOPTS;
+		if (!flags)
 			return;
+	}
 
-	if (flags & 1)
+	if (flags & IP_CMSG_RETOPTS) {
 		ip_cmsg_recv_retopts(msg, skb);
-	if ((flags >>= 1) == 0)
+
+		flags &= ~IP_CMSG_RETOPTS;
+		if (!flags)
 			return;
+	}
 
-	if (flags & 1)
+	if (flags & IP_CMSG_PASSSEC) {
 		ip_cmsg_recv_security(msg, skb);
 
-	if ((flags >>= 1) == 0)
+		flags &= ~IP_CMSG_PASSSEC;
+		if (!flags)
 			return;
-	if (flags & 1)
+	}
+
+	if (flags & IP_CMSG_ORIGDSTADDR)
 		ip_cmsg_recv_dstaddr(msg, skb);
 
 }