Subject: Re: [PATCH]: net: Use hton[sl]() was Re: [PATCH 10/14] Phonet: Phonet datagram transport protocol

From: Piet Delaney <[email-masked]>
Date: Fri, 14 Nov 2008 00:32:51 -0800

Arnaldo Carvalho de Melo wrote:
> Em Fri, Sep 19, 2008 at 09:33:33AM +0300, Rémi Denis-Courmont escreveu:
>> On Tuesday 16 September 2008 20:06:44 ext Arnaldo Carvalho de Melo, you wrote:
>>>> +	ph->robj = pn_obj(dst);
>>>> +	ph->sobj = pn_obj(src);
>>>> +
>>>> +	skb->protocol = __constant_htons(ETH_P_PHONET);
>>> No need for __constant_htons(CONSTANT), htons will do the right thing
>>> and the code will be shorter, clearer.
>> Ok. There are quite many of these in net/ though... is that reserved for 
>> switch/case only?
> 
> Nope, they should only be used when initializing static variables.

I see more downside with this patch with it's preventing the kernel
from being compiled -O0 when using kgdb or looking at KEXEC/KDUMP
core files with gdb.

-piet

> 
> David, the following patch converts what is in net-next-2.6 net/ now:
> 
> 
> commit 8e64a880d1f8a3df44648e0109f22a22322acc56
> Author: Arnaldo Carvalho de Melo <[email-masked]>
> Date:   Fri Sep 19 11:34:45 2008 -0300
> 
>     net: Use hton[sl]() instead of __constant_hton[sl]() where applicable
>     
>     Signed-off-by: Arnaldo Carvalho de Melo <[email-masked]>
> 
> diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
> index 97688cd..8883e9c 100644
> --- a/net/8021q/vlan_dev.c
> +++ b/net/8021q/vlan_dev.c
> @@ -48,7 +48,7 @@ static int vlan_dev_rebuild_header(struct sk_buff *skb)
>  
>  	switch (veth->h_vlan_encapsulated_proto) {
>  #ifdef CONFIG_INET
> -	case __constant_htons(ETH_P_IP):
> +	case htons(ETH_P_IP):
>  
>  		/* TODO:  Confirm this will work with VLAN headers... */
>  		return arp_find(veth->h_dest, skb);
> diff --git a/net/atm/br2684.c b/net/atm/br2684.c
> index 8d9a6f1..280de48 100644
> --- a/net/atm/br2684.c
> +++ b/net/atm/br2684.c
> @@ -375,11 +375,11 @@ static void br2684_push(struct atm_vcc *atmvcc, struct sk_buff *skb)
>  			if (memcmp
>  			    (skb->data + 6, ethertype_ipv6,
>  			     sizeof(ethertype_ipv6)) == 0)
> -				skb->protocol = __constant_htons(ETH_P_IPV6);
> +				skb->protocol = htons(ETH_P_IPV6);
>  			else if (memcmp
>  				 (skb->data + 6, ethertype_ipv4,
>  				  sizeof(ethertype_ipv4)) == 0)
> -				skb->protocol = __constant_htons(ETH_P_IP);
> +				skb->protocol = htons(ETH_P_IP);
>  			else
>  				goto error;
>  			skb_pull(skb, sizeof(llc_oui_ipv4));
> @@ -404,9 +404,9 @@ static void br2684_push(struct atm_vcc *atmvcc, struct sk_buff *skb)
>  			skb_reset_network_header(skb);
>  			iph = ip_hdr(skb);
>  			if (iph->version == 4)
> -				skb->protocol = __constant_htons(ETH_P_IP);
> +				skb->protocol = htons(ETH_P_IP);
>  			else if (iph->version == 6)
> -				skb->protocol = __constant_htons(ETH_P_IPV6);
> +				skb->protocol = htons(ETH_P_IPV6);
>  			else
>  				goto error;
>  			skb->pkt_type = PACKET_HOST;
> diff --git a/net/core/dev.c b/net/core/dev.c
> index f48d1b2..fdfc4b6 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -1675,13 +1675,13 @@ static u16 simple_tx_hash(struct net_device *dev, struct sk_buff *skb)
>  	}
>  
>  	switch (skb->protocol) {
> -	case __constant_htons(ETH_P_IP):
> +	case htons(ETH_P_IP):
>  		ip_proto = ip_hdr(skb)->protocol;
>  		addr1 = ip_hdr(skb)->saddr;
>  		addr2 = ip_hdr(skb)->daddr;
>  		ihl = ip_hdr(skb)->ihl;
>  		break;
> -	case __constant_htons(ETH_P_IPV6):
> +	case htons(ETH_P_IPV6):
>  		ip_proto = ipv6_hdr(skb)->nexthdr;
>  		addr1 = ipv6_hdr(skb)->saddr.s6_addr32[3];
>  		addr2 = ipv6_hdr(skb)->daddr.s6_addr32[3];
> diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
> index a80839b..647a9ed 100644
> --- a/net/ethernet/eth.c
> +++ b/net/ethernet/eth.c
> @@ -129,7 +129,7 @@ int eth_rebuild_header(struct sk_buff *skb)
>  
>  	switch (eth->h_proto) {
>  #ifdef CONFIG_INET
> -	case __constant_htons(ETH_P_IP):
> +	case htons(ETH_P_IP):
>  		return arp_find(eth->h_dest, skb);
>  #endif
>  	default:
> diff --git a/net/ipv4/ipvs/ip_vs_core.c b/net/ipv4/ipvs/ip_vs_core.c
> index ece748d..958abf3 100644
> --- a/net/ipv4/ipvs/ip_vs_core.c
> +++ b/net/ipv4/ipvs/ip_vs_core.c
> @@ -938,7 +938,7 @@ ip_vs_out(unsigned int hooknum, struct sk_buff *skb,
>  
>  	EnterFunction(11);
>  
> -	af = (skb->protocol == __constant_htons(ETH_P_IP)) ? AF_INET : AF_INET6;
> +	af = (skb->protocol == htons(ETH_P_IP)) ? AF_INET : AF_INET6;
>  
>  	if (skb->ipvs_property)
>  		return NF_ACCEPT;
> @@ -1258,7 +1258,7 @@ ip_vs_in(unsigned int hooknum, struct sk_buff *skb,
>  	struct ip_vs_conn *cp;
>  	int ret, restart, af;
>  
> -	af = (skb->protocol == __constant_htons(ETH_P_IP)) ? AF_INET : AF_INET6;
> +	af = (skb->protocol == htons(ETH_P_IP)) ? AF_INET : AF_INET6;
>  
>  	ip_vs_fill_iphdr(af, skb_network_header(skb), &iph);
>  
> diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
> index 17c7b09..64ce3d3 100644
> --- a/net/ipv6/ip6_tunnel.c
> +++ b/net/ipv6/ip6_tunnel.c
> @@ -1050,10 +1050,10 @@ ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
>  	}
>  
>  	switch (skb->protocol) {
> -	case __constant_htons(ETH_P_IP):
> +	case htons(ETH_P_IP):
>  		ret = ip4ip6_tnl_xmit(skb, dev);
>  		break;
> -	case __constant_htons(ETH_P_IPV6):
> +	case htons(ETH_P_IPV6):
>  		ret = ip6ip6_tnl_xmit(skb, dev);
>  		break;
>  	default:
> diff --git a/net/mac80211/wme.c b/net/mac80211/wme.c
> index 7229e95..5966b9f 100644
> --- a/net/mac80211/wme.c
> +++ b/net/mac80211/wme.c
> @@ -39,7 +39,7 @@ static unsigned int classify_1d(struct sk_buff *skb)
>  		return skb->priority - 256;
>  
>  	switch (skb->protocol) {
> -	case __constant_htons(ETH_P_IP):
> +	case htons(ETH_P_IP):
>  		dscp = ip_hdr(skb)->tos & 0xfc;
>  		break;
>  
> diff --git a/net/sched/cls_flow.c b/net/sched/cls_flow.c
> index 8f63a1a..0ebaff6 100644
> --- a/net/sched/cls_flow.c
> +++ b/net/sched/cls_flow.c
> @@ -67,9 +67,9 @@ static inline u32 addr_fold(void *addr)
>  static u32 flow_get_src(const struct sk_buff *skb)
>  {
>  	switch (skb->protocol) {
> -	case __constant_htons(ETH_P_IP):
> +	case htons(ETH_P_IP):
>  		return ntohl(ip_hdr(skb)->saddr);
> -	case __constant_htons(ETH_P_IPV6):
> +	case htons(ETH_P_IPV6):
>  		return ntohl(ipv6_hdr(skb)->saddr.s6_addr32[3]);
>  	default:
>  		return addr_fold(skb->sk);
> @@ -79,9 +79,9 @@ static u32 flow_get_src(const struct sk_buff *skb)
>  static u32 flow_get_dst(const struct sk_buff *skb)
>  {
>  	switch (skb->protocol) {
> -	case __constant_htons(ETH_P_IP):
> +	case htons(ETH_P_IP):
>  		return ntohl(ip_hdr(skb)->daddr);
> -	case __constant_htons(ETH_P_IPV6):
> +	case htons(ETH_P_IPV6):
>  		return ntohl(ipv6_hdr(skb)->daddr.s6_addr32[3]);
>  	default:
>  		return addr_fold(skb->dst) ^ (__force u16)skb->protocol;
> @@ -91,9 +91,9 @@ static u32 flow_get_dst(const struct sk_buff *skb)
>  static u32 flow_get_proto(const struct sk_buff *skb)
>  {
>  	switch (skb->protocol) {
> -	case __constant_htons(ETH_P_IP):
> +	case htons(ETH_P_IP):
>  		return ip_hdr(skb)->protocol;
> -	case __constant_htons(ETH_P_IPV6):
> +	case htons(ETH_P_IPV6):
>  		return ipv6_hdr(skb)->nexthdr;
>  	default:
>  		return 0;
> @@ -120,7 +120,7 @@ static u32 flow_get_proto_src(const struct sk_buff *skb)
>  	u32 res = 0;
>  
>  	switch (skb->protocol) {
> -	case __constant_htons(ETH_P_IP): {
> +	case htons(ETH_P_IP): {
>  		struct iphdr *iph = ip_hdr(skb);
>  
>  		if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&
> @@ -128,7 +128,7 @@ static u32 flow_get_proto_src(const struct sk_buff *skb)
>  			res = ntohs(*(__be16 *)((void *)iph + iph->ihl * 4));
>  		break;
>  	}
> -	case __constant_htons(ETH_P_IPV6): {
> +	case htons(ETH_P_IPV6): {
>  		struct ipv6hdr *iph = ipv6_hdr(skb);
>  
>  		if (has_ports(iph->nexthdr))
> @@ -147,7 +147,7 @@ static u32 flow_get_proto_dst(const struct sk_buff *skb)
>  	u32 res = 0;
>  
>  	switch (skb->protocol) {
> -	case __constant_htons(ETH_P_IP): {
> +	case htons(ETH_P_IP): {
>  		struct iphdr *iph = ip_hdr(skb);
>  
>  		if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&
> @@ -155,7 +155,7 @@ static u32 flow_get_proto_dst(const struct sk_buff *skb)
>  			res = ntohs(*(__be16 *)((void *)iph + iph->ihl * 4 + 2));
>  		break;
>  	}
> -	case __constant_htons(ETH_P_IPV6): {
> +	case htons(ETH_P_IPV6): {
>  		struct ipv6hdr *iph = ipv6_hdr(skb);
>  
>  		if (has_ports(iph->nexthdr))
> @@ -213,9 +213,9 @@ static u32 flow_get_nfct(const struct sk_buff *skb)
>  static u32 flow_get_nfct_src(const struct sk_buff *skb)
>  {
>  	switch (skb->protocol) {
> -	case __constant_htons(ETH_P_IP):
> +	case htons(ETH_P_IP):
>  		return ntohl(CTTUPLE(skb, src.u3.ip));
> -	case __constant_htons(ETH_P_IPV6):
> +	case htons(ETH_P_IPV6):
>  		return ntohl(CTTUPLE(skb, src.u3.ip6[3]));
>  	}
>  fallback:
> @@ -225,9 +225,9 @@ fallback:
>  static u32 flow_get_nfct_dst(const struct sk_buff *skb)
>  {
>  	switch (skb->protocol) {
> -	case __constant_htons(ETH_P_IP):
> +	case htons(ETH_P_IP):
>  		return ntohl(CTTUPLE(skb, dst.u3.ip));
> -	case __constant_htons(ETH_P_IPV6):
> +	case htons(ETH_P_IPV6):
>  		return ntohl(CTTUPLE(skb, dst.u3.ip6[3]));
>  	}
>  fallback:
> diff --git a/net/sched/sch_dsmark.c b/net/sched/sch_dsmark.c
> index edd1298..ba43aab 100644
> --- a/net/sched/sch_dsmark.c
> +++ b/net/sched/sch_dsmark.c
> @@ -202,7 +202,7 @@ static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch)
>  
>  	if (p->set_tc_index) {
>  		switch (skb->protocol) {
> -		case __constant_htons(ETH_P_IP):
> +		case htons(ETH_P_IP):
>  			if (skb_cow_head(skb, sizeof(struct iphdr)))
>  				goto drop;
>  
> @@ -210,7 +210,7 @@ static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch)
>  				& ~INET_ECN_MASK;
>  			break;
>  
> -		case __constant_htons(ETH_P_IPV6):
> +		case htons(ETH_P_IPV6):
>  			if (skb_cow_head(skb, sizeof(struct ipv6hdr)))
>  				goto drop;
>  
> @@ -289,11 +289,11 @@ static struct sk_buff *dsmark_dequeue(struct Qdisc *sch)
>  	pr_debug("index %d->%d\n", skb->tc_index, index);
>  
>  	switch (skb->protocol) {
> -	case __constant_htons(ETH_P_IP):
> +	case htons(ETH_P_IP):
>  		ipv4_change_dsfield(ip_hdr(skb), p->mask[index],
>  				    p->value[index]);
>  			break;
> -	case __constant_htons(ETH_P_IPV6):
> +	case htons(ETH_P_IPV6):
>  		ipv6_change_dsfield(ipv6_hdr(skb), p->mask[index],
>  				    p->value[index]);
>  			break;
> diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
> index 6e041d1..fe1508e 100644
> --- a/net/sched/sch_sfq.c
> +++ b/net/sched/sch_sfq.c
> @@ -119,7 +119,7 @@ static unsigned sfq_hash(struct sfq_sched_data *q, struct sk_buff *skb)
>  	u32 h, h2;
>  
>  	switch (skb->protocol) {
> -	case __constant_htons(ETH_P_IP):
> +	case htons(ETH_P_IP):
>  	{
>  		const struct iphdr *iph = ip_hdr(skb);
>  		h = iph->daddr;
> @@ -134,7 +134,7 @@ static unsigned sfq_hash(struct sfq_sched_data *q, struct sk_buff *skb)
>  			h2 ^= *(((u32*)iph) + iph->ihl);
>  		break;
>  	}
> -	case __constant_htons(ETH_P_IPV6):
> +	case htons(ETH_P_IPV6):
>  	{
>  		struct ipv6hdr *iph = ipv6_hdr(skb);
>  		h = iph->daddr.s6_addr32[3];
> diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
> index e55427f..5c1954d 100644
> --- a/net/sunrpc/xprtrdma/rpc_rdma.c
> +++ b/net/sunrpc/xprtrdma/rpc_rdma.c
> @@ -769,7 +769,7 @@ repost:
>  	/* check for expected message types */
>  	/* The order of some of these tests is important. */
>  	switch (headerp->rm_type) {
> -	case __constant_htonl(RDMA_MSG):
> +	case htonl(RDMA_MSG):
>  		/* never expect read chunks */
>  		/* never expect reply chunks (two ways to check) */
>  		/* never expect write chunks without having offered RDMA */
> @@ -802,7 +802,7 @@ repost:
>  		rpcrdma_inline_fixup(rqst, (char *)iptr, rep->rr_len);
>  		break;
>  
> -	case __constant_htonl(RDMA_NOMSG):
> +	case htonl(RDMA_NOMSG):
>  		/* never expect read or write chunks, always reply chunks */
>  		if (headerp->rm_body.rm_chunks[0] != xdr_zero ||
>  		    headerp->rm_body.rm_chunks[1] != xdr_zero ||
> --
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