ip_tunnel: convert __be16 tunnel flags to bitmaps

Historically, tunnel flags like TUNNEL_CSUM or TUNNEL_ERSPAN_OPT
have been defined as __be16. Now all of those 16 bits are occupied
and there's no more free space for new flags.
It can't be simply switched to a bigger container with no
adjustments to the values, since it's an explicit Endian storage,
and on LE systems (__be16)0x0001 equals to
(__be64)0x0001000000000000.
We could probably define new 64-bit flags depending on the
Endianness, i.e. (__be64)0x0001 on BE and (__be64)0x00010000... on
LE, but that would introduce an Endianness dependency and spawn a
ton of Sparse warnings. To mitigate them, all of those places which
were adjusted with this change would be touched anyway, so why not
define stuff properly if there's no choice.

Define IP_TUNNEL_*_BIT counterparts as a bit number instead of the
value already coded and a fistful of <16 <-> bitmap> converters and
helpers. The two flags which have a different bit position are
SIT_ISATAP_BIT and VTI_ISVTI_BIT, as they were defined not as
__cpu_to_be16(), but as (__force __be16), i.e. had different
positions on LE and BE. Now they both have strongly defined places.
Change all __be16 fields which were used to store those flags, to
IP_TUNNEL_DECLARE_FLAGS() -> DECLARE_BITMAP(__IP_TUNNEL_FLAG_NUM) ->
unsigned long[1] for now, and replace all TUNNEL_* occurrences to
their bitmap counterparts. Use the converters in the places which talk
to the userspace, hardware (NFP) or other hosts (GRE header). The rest
must explicitly use the new flags only. This must be done at once,
otherwise there will be too many conversions throughout the code in
the intermediate commits.
Finally, disable the old __be16 flags for use in the kernel code
(except for the two 'irregular' flags mentioned above), to prevent
any accidental (mis)use of them. For the userspace, nothing is
changed, only additions were made.

Most noticeable bloat-o-meter difference (.text):

vmlinux:	307/-1 (306)
gre.ko:		62/0 (62)
ip_gre.ko:	941/-217 (724)	[*]
ip_tunnel.ko:	390/-900 (-510)	[**]
ip_vti.ko:	138/0 (138)
ip6_gre.ko:	534/-18 (516)	[*]
ip6_tunnel.ko:	118/-10 (108)

[*] gre_flags_to_tnl_flags() grew, but still is inlined
[**] ip_tunnel_find() got uninlined, hence such decrease

The average code size increase in non-extreme case is 100-200 bytes
per module, mostly due to sizeof(long) > sizeof(__be16), as
%__IP_TUNNEL_FLAG_NUM is less than %BITS_PER_LONG and the compilers
are able to expand the majority of bitmap_*() calls here into direct
operations on scalars.

Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 59 insertions, 45 deletions

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index ca7e77e84283..2146cf69d8e2 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -496,11 +496,11 @@ static int ip6gre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi)
 				      tpi->proto);
 	if (tunnel) {
 		if (tunnel->parms.collect_md) {
+			IP_TUNNEL_DECLARE_FLAGS(flags);
 			struct metadata_dst *tun_dst;
 			__be64 tun_id;
-			__be16 flags;
 
-			flags = tpi->flags;
+			ip_tunnel_flags_copy(flags, tpi->flags);
 			tun_id = key32_to_tunnel_id(tpi->key);
 
 			tun_dst = ipv6_tun_rx_dst(skb, flags, tun_id, 0);
@@ -548,14 +548,14 @@ static int ip6erspan_rcv(struct sk_buff *skb,
 
 		if (tunnel->parms.collect_md) {
 			struct erspan_metadata *pkt_md, *md;
+			IP_TUNNEL_DECLARE_FLAGS(flags);
 			struct metadata_dst *tun_dst;
 			struct ip_tunnel_info *info;
 			unsigned char *gh;
 			__be64 tun_id;
-			__be16 flags;
 
-			tpi->flags |= TUNNEL_KEY;
-			flags = tpi->flags;
+			__set_bit(IP_TUNNEL_KEY_BIT, tpi->flags);
+			ip_tunnel_flags_copy(flags, tpi->flags);
 			tun_id = key32_to_tunnel_id(tpi->key);
 
 			tun_dst = ipv6_tun_rx_dst(skb, flags, tun_id,
@@ -577,7 +577,8 @@ static int ip6erspan_rcv(struct sk_buff *skb,
 			md2 = &md->u.md2;
 			memcpy(md2, pkt_md, ver == 1 ? ERSPAN_V1_MDSIZE :
 						       ERSPAN_V2_MDSIZE);
-			info->key.tun_flags |= TUNNEL_ERSPAN_OPT;
+			__set_bit(IP_TUNNEL_ERSPAN_OPT_BIT,
+				  info->key.tun_flags);
 			info->options_len = sizeof(*md);
 
 			ip6_tnl_rcv(tunnel, skb, tpi, tun_dst, log_ecn_error);
@@ -745,8 +746,8 @@ static netdev_tx_t __gre6_xmit(struct sk_buff *skb,
 			       __u32 *pmtu, __be16 proto)
 {
 	struct ip6_tnl *tunnel = netdev_priv(dev);
+	IP_TUNNEL_DECLARE_FLAGS(flags);
 	__be16 protocol;
-	__be16 flags;
 
 	if (dev->type == ARPHRD_ETHER)
 		IPCB(skb)->flags = 0;
@@ -778,8 +779,11 @@ static netdev_tx_t __gre6_xmit(struct sk_buff *skb,
 		fl6->fl6_gre_key = tunnel_id_to_key32(key->tun_id);
 
 		dsfield = key->tos;
-		flags = key->tun_flags &
-			(TUNNEL_CSUM | TUNNEL_KEY | TUNNEL_SEQ);
+		ip_tunnel_flags_zero(flags);
+		__set_bit(IP_TUNNEL_CSUM_BIT, flags);
+		__set_bit(IP_TUNNEL_KEY_BIT, flags);
+		__set_bit(IP_TUNNEL_SEQ_BIT, flags);
+		ip_tunnel_flags_and(flags, flags, key->tun_flags);
 		tun_hlen = gre_calc_hlen(flags);
 
 		if (skb_cow_head(skb, dev->needed_headroom ?: tun_hlen + tunnel->encap_hlen))
@@ -788,19 +792,21 @@ static netdev_tx_t __gre6_xmit(struct sk_buff *skb,
 		gre_build_header(skb, tun_hlen,
 				 flags, protocol,
 				 tunnel_id_to_key32(tun_info->key.tun_id),
-				 (flags & TUNNEL_SEQ) ? htonl(atomic_fetch_inc(&tunnel->o_seqno))
-						      : 0);
+				 test_bit(IP_TUNNEL_SEQ_BIT, flags) ?
+				 htonl(atomic_fetch_inc(&tunnel->o_seqno)) :
+				 0);
 
 	} else {
 		if (skb_cow_head(skb, dev->needed_headroom ?: tunnel->hlen))
 			return -ENOMEM;
 
-		flags = tunnel->parms.o_flags;
+		ip_tunnel_flags_copy(flags, tunnel->parms.o_flags);
 
 		gre_build_header(skb, tunnel->tun_hlen, flags,
 				 protocol, tunnel->parms.o_key,
-				 (flags & TUNNEL_SEQ) ? htonl(atomic_fetch_inc(&tunnel->o_seqno))
-						      : 0);
+				 test_bit(IP_TUNNEL_SEQ_BIT, flags) ?
+				 htonl(atomic_fetch_inc(&tunnel->o_seqno)) :
+				 0);
 	}
 
 	return ip6_tnl_xmit(skb, dev, dsfield, fl6, encap_limit, pmtu,
@@ -822,7 +828,8 @@ static inline int ip6gre_xmit_ipv4(struct sk_buff *skb, struct net_device *dev)
 		prepare_ip6gre_xmit_ipv4(skb, dev, &fl6,
 					 &dsfield, &encap_limit);
 
-	err = gre_handle_offloads(skb, !!(t->parms.o_flags & TUNNEL_CSUM));
+	err = gre_handle_offloads(skb, test_bit(IP_TUNNEL_CSUM_BIT,
+						t->parms.o_flags));
 	if (err)
 		return -1;
 
@@ -856,7 +863,8 @@ static inline int ip6gre_xmit_ipv6(struct sk_buff *skb, struct net_device *dev)
 	    prepare_ip6gre_xmit_ipv6(skb, dev, &fl6, &dsfield, &encap_limit))
 		return -1;
 
-	if (gre_handle_offloads(skb, !!(t->parms.o_flags & TUNNEL_CSUM)))
+	if (gre_handle_offloads(skb, test_bit(IP_TUNNEL_CSUM_BIT,
+					      t->parms.o_flags)))
 		return -1;
 
 	err = __gre6_xmit(skb, dev, dsfield, &fl6, encap_limit,
@@ -883,7 +891,8 @@ static int ip6gre_xmit_other(struct sk_buff *skb, struct net_device *dev)
 	    prepare_ip6gre_xmit_other(skb, dev, &fl6, &dsfield, &encap_limit))
 		return -1;
 
-	err = gre_handle_offloads(skb, !!(t->parms.o_flags & TUNNEL_CSUM));
+	err = gre_handle_offloads(skb, test_bit(IP_TUNNEL_CSUM_BIT,
+						t->parms.o_flags));
 	if (err)
 		return err;
 	err = __gre6_xmit(skb, dev, dsfield, &fl6, encap_limit, &mtu, skb->protocol);
@@ -936,6 +945,7 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
 	struct ip_tunnel_info *tun_info = NULL;
 	struct ip6_tnl *t = netdev_priv(dev);
 	struct dst_entry *dst = skb_dst(skb);
+	IP_TUNNEL_DECLARE_FLAGS(flags) = { };
 	bool truncate = false;
 	int encap_limit = -1;
 	__u8 dsfield = false;
@@ -979,7 +989,7 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
 	if (skb_cow_head(skb, dev->needed_headroom ?: t->hlen))
 		goto tx_err;
 
-	t->parms.o_flags &= ~TUNNEL_KEY;
+	__clear_bit(IP_TUNNEL_KEY_BIT, t->parms.o_flags);
 	IPCB(skb)->flags = 0;
 
 	/* For collect_md mode, derive fl6 from the tunnel key,
@@ -1004,7 +1014,8 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
 		fl6.fl6_gre_key = tunnel_id_to_key32(key->tun_id);
 
 		dsfield = key->tos;
-		if (!(tun_info->key.tun_flags & TUNNEL_ERSPAN_OPT))
+		if (!test_bit(IP_TUNNEL_ERSPAN_OPT_BIT,
+			      tun_info->key.tun_flags))
 			goto tx_err;
 		if (tun_info->options_len < sizeof(*md))
 			goto tx_err;
@@ -1065,7 +1076,9 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb,
 	}
 
 	/* Push GRE header. */
-	gre_build_header(skb, 8, TUNNEL_SEQ, proto, 0, htonl(atomic_fetch_inc(&t->o_seqno)));
+	__set_bit(IP_TUNNEL_SEQ_BIT, flags);
+	gre_build_header(skb, 8, flags, proto, 0,
+			 htonl(atomic_fetch_inc(&t->o_seqno)));
 
 	/* TooBig packet may have updated dst->dev's mtu */
 	if (!t->parms.collect_md && dst && dst_mtu(dst) > dst->dev->mtu)
@@ -1208,8 +1221,8 @@ static void ip6gre_tnl_copy_tnl_parm(struct ip6_tnl *t,
 	t->parms.proto = p->proto;
 	t->parms.i_key = p->i_key;
 	t->parms.o_key = p->o_key;
-	t->parms.i_flags = p->i_flags;
-	t->parms.o_flags = p->o_flags;
+	ip_tunnel_flags_copy(t->parms.i_flags, p->i_flags);
+	ip_tunnel_flags_copy(t->parms.o_flags, p->o_flags);
 	t->parms.fwmark = p->fwmark;
 	t->parms.erspan_ver = p->erspan_ver;
 	t->parms.index = p->index;
@@ -1238,8 +1251,8 @@ static void ip6gre_tnl_parm_from_user(struct __ip6_tnl_parm *p,
 	p->link = u->link;
 	p->i_key = u->i_key;
 	p->o_key = u->o_key;
-	p->i_flags = gre_flags_to_tnl_flags(u->i_flags);
-	p->o_flags = gre_flags_to_tnl_flags(u->o_flags);
+	gre_flags_to_tnl_flags(p->i_flags, u->i_flags);
+	gre_flags_to_tnl_flags(p->o_flags, u->o_flags);
 	memcpy(p->name, u->name, sizeof(u->name));
 }
 
@@ -1391,7 +1404,7 @@ static int ip6gre_header(struct sk_buff *skb, struct net_device *dev,
 	ipv6h->daddr = t->parms.raddr;
 
 	p = (__be16 *)(ipv6h + 1);
-	p[0] = t->parms.o_flags;
+	p[0] = ip_tunnel_flags_to_be16(t->parms.o_flags);
 	p[1] = htons(type);
 
 	/*
@@ -1455,19 +1468,17 @@ static void ip6gre_tunnel_setup(struct net_device *dev)
 static void ip6gre_tnl_init_features(struct net_device *dev)
 {
 	struct ip6_tnl *nt = netdev_priv(dev);
-	__be16 flags;
 
 	dev->features		|= GRE6_FEATURES | NETIF_F_LLTX;
 	dev->hw_features	|= GRE6_FEATURES;
 
-	flags = nt->parms.o_flags;
-
 	/* TCP offload with GRE SEQ is not supported, nor can we support 2
 	 * levels of outer headers requiring an update.
 	 */
-	if (flags & TUNNEL_SEQ)
+	if (test_bit(IP_TUNNEL_SEQ_BIT, nt->parms.o_flags))
 		return;
-	if (flags & TUNNEL_CSUM && nt->encap.type != TUNNEL_ENCAP_NONE)
+	if (test_bit(IP_TUNNEL_CSUM_BIT, nt->parms.o_flags) &&
+	    nt->encap.type != TUNNEL_ENCAP_NONE)
 		return;
 
 	dev->features |= NETIF_F_GSO_SOFTWARE;
@@ -1792,12 +1803,12 @@ static void ip6gre_netlink_parms(struct nlattr *data[],
 		parms->link = nla_get_u32(data[IFLA_GRE_LINK]);
 
 	if (data[IFLA_GRE_IFLAGS])
-		parms->i_flags = gre_flags_to_tnl_flags(
-				nla_get_be16(data[IFLA_GRE_IFLAGS]));
+		gre_flags_to_tnl_flags(parms->i_flags,
+				       nla_get_be16(data[IFLA_GRE_IFLAGS]));
 
 	if (data[IFLA_GRE_OFLAGS])
-		parms->o_flags = gre_flags_to_tnl_flags(
-				nla_get_be16(data[IFLA_GRE_OFLAGS]));
+		gre_flags_to_tnl_flags(parms->o_flags,
+				       nla_get_be16(data[IFLA_GRE_OFLAGS]));
 
 	if (data[IFLA_GRE_IKEY])
 		parms->i_key = nla_get_be32(data[IFLA_GRE_IKEY]);
@@ -2144,11 +2155,13 @@ static int ip6gre_fill_info(struct sk_buff *skb, const struct net_device *dev)
 {
 	struct ip6_tnl *t = netdev_priv(dev);
 	struct __ip6_tnl_parm *p = &t->parms;
-	__be16 o_flags = p->o_flags;
+	IP_TUNNEL_DECLARE_FLAGS(o_flags);
+
+	ip_tunnel_flags_copy(o_flags, p->o_flags);
 
 	if (p->erspan_ver == 1 || p->erspan_ver == 2) {
 		if (!p->collect_md)
-			o_flags |= TUNNEL_KEY;
+			__set_bit(IP_TUNNEL_KEY_BIT, o_flags);
 
 		if (nla_put_u8(skb, IFLA_GRE_ERSPAN_VER, p->erspan_ver))
 			goto nla_put_failure;
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index e9cc315832cb..57bb3b3ea0c5 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -798,17 +798,15 @@ static int __ip6_tnl_rcv(struct ip6_tnl *tunnel, struct sk_buff *skb,
 	const struct ipv6hdr *ipv6h;
 	int nh, err;
 
-	if ((!(tpi->flags & TUNNEL_CSUM) &&
-	     (tunnel->parms.i_flags & TUNNEL_CSUM)) ||
-	    ((tpi->flags & TUNNEL_CSUM) &&
-	     !(tunnel->parms.i_flags & TUNNEL_CSUM))) {
+	if (test_bit(IP_TUNNEL_CSUM_BIT, tunnel->parms.i_flags) !=
+	    test_bit(IP_TUNNEL_CSUM_BIT, tpi->flags)) {
 		DEV_STATS_INC(tunnel->dev, rx_crc_errors);
 		DEV_STATS_INC(tunnel->dev, rx_errors);
 		goto drop;
 	}
 
-	if (tunnel->parms.i_flags & TUNNEL_SEQ) {
-		if (!(tpi->flags & TUNNEL_SEQ) ||
+	if (test_bit(IP_TUNNEL_SEQ_BIT, tunnel->parms.i_flags)) {
+		if (!test_bit(IP_TUNNEL_SEQ_BIT, tpi->flags) ||
 		    (tunnel->i_seqno &&
 		     (s32)(ntohl(tpi->seq) - tunnel->i_seqno) < 0)) {
 			DEV_STATS_INC(tunnel->dev, rx_fifo_errors);
@@ -946,7 +944,9 @@ static int ipxip6_rcv(struct sk_buff *skb, u8 ipproto,
 		if (iptunnel_pull_header(skb, 0, tpi->proto, false))
 			goto drop;
 		if (t->parms.collect_md) {
-			tun_dst = ipv6_tun_rx_dst(skb, 0, 0, 0);
+			IP_TUNNEL_DECLARE_FLAGS(flags) = { };
+
+			tun_dst = ipv6_tun_rx_dst(skb, flags, 0, 0);
 			if (!tun_dst)
 				goto drop;
 		}
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 894e6a4c4be3..83b195f09561 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -207,7 +207,7 @@ static int ipip6_tunnel_create(struct net_device *dev)
 	__dev_addr_set(dev, &t->parms.iph.saddr, 4);
 	memcpy(dev->broadcast, &t->parms.iph.daddr, 4);
 
-	if ((__force u16)t->parms.i_flags & SIT_ISATAP)
+	if (test_bit(IP_TUNNEL_SIT_ISATAP_BIT, t->parms.i_flags))
 		dev->priv_flags |= IFF_ISATAP;
 
 	dev->rtnl_link_ops = &sit_link_ops;
@@ -1700,7 +1700,8 @@ static int ipip6_fill_info(struct sk_buff *skb, const struct net_device *dev)
 	    nla_put_u8(skb, IFLA_IPTUN_PMTUDISC,
 		       !!(parm->iph.frag_off & htons(IP_DF))) ||
 	    nla_put_u8(skb, IFLA_IPTUN_PROTO, parm->iph.protocol) ||
-	    nla_put_be16(skb, IFLA_IPTUN_FLAGS, parm->i_flags) ||
+	    nla_put_be16(skb, IFLA_IPTUN_FLAGS,
+			 ip_tunnel_flags_to_be16(parm->i_flags)) ||
 	    nla_put_u32(skb, IFLA_IPTUN_FWMARK, tunnel->fwmark))
 		goto nla_put_failure;