netns: make struct pernet_operations::id unsigned int

Make struct pernet_operations::id unsigned.

There are 2 reasons to do so:

1)
This field is really an index into an zero based array and
thus is unsigned entity. Using negative value is out-of-bound
access by definition.

2)
On x86_64 unsigned 32-bit data which are mixed with pointers
via array indexing or offsets added or subtracted to pointers
are preffered to signed 32-bit data.

"int" being used as an array index needs to be sign-extended
to 64-bit before being used.

	void f(long *p, int i)
	{
		g(p[i]);
	}

  roughly translates to

	movsx	rsi, esi
	mov	rdi, [rsi+...]
	call 	g

MOVSX is 3 byte instruction which isn't necessary if the variable is
unsigned because x86_64 is zero extending by default.

Now, there is net_generic() function which, you guessed it right, uses
"int" as an array index:

	static inline void *net_generic(const struct net *net, int id)
	{
		...
		ptr = ng->ptr[id - 1];
		...
	}

And this function is used a lot, so those sign extensions add up.

Patch snipes ~1730 bytes on allyesconfig kernel (without all junk
messing with code generation):

	add/remove: 0/0 grow/shrink: 70/598 up/down: 396/-2126 (-1730)

Unfortunately some functions actually grow bigger.
This is a semmingly random artefact of code generation with register
allocator being used differently. gcc decides that some variable
needs to live in new r8+ registers and every access now requires REX
prefix. Or it is shifted into r12, so [r12+0] addressing mode has to be
used which is longer than [r8]

However, overall balance is in negative direction:

	add/remove: 0/0 grow/shrink: 70/598 up/down: 396/-2126 (-1730)
	function                                     old     new   delta
	nfsd4_lock                                  3886    3959     +73
	tipc_link_build_proto_msg                   1096    1140     +44
	mac80211_hwsim_new_radio                    2776    2808     +32
	tipc_mon_rcv                                1032    1058     +26
	svcauth_gss_legacy_init                     1413    1429     +16
	tipc_bcbase_select_primary                   379     392     +13
	nfsd4_exchange_id                           1247    1260     +13
	nfsd4_setclientid_confirm                    782     793     +11
		...
	put_client_renew_locked                      494     480     -14
	ip_set_sockfn_get                            730     716     -14
	geneve_sock_add                              829     813     -16
	nfsd4_sequence_done                          721     703     -18
	nlmclnt_lookup_host                          708     686     -22
	nfsd4_lockt                                 1085    1063     -22
	nfs_get_client                              1077    1050     -27
	tcf_bpf_init                                1106    1076     -30
	nfsd4_encode_fattr                          5997    5930     -67
	Total: Before=154856051, After=154854321, chg -0.00%

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 7 insertions, 7 deletions

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 576f705d8180..78fd62048335 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -113,8 +113,8 @@ MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");
 static struct rtnl_link_ops ipgre_link_ops __read_mostly;
 static int ipgre_tunnel_init(struct net_device *dev);
 
-static int ipgre_net_id __read_mostly;
-static int gre_tap_net_id __read_mostly;
+static unsigned int ipgre_net_id __read_mostly;
+static unsigned int gre_tap_net_id __read_mostly;
 
 static void ipgre_err(struct sk_buff *skb, u32 info,
 		      const struct tnl_ptk_info *tpi)
diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 12a92e3349ed..823abaef006b 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -994,7 +994,7 @@ int ip_tunnel_get_iflink(const struct net_device *dev)
 }
 EXPORT_SYMBOL(ip_tunnel_get_iflink);
 
-int ip_tunnel_init_net(struct net *net, int ip_tnl_net_id,
+int ip_tunnel_init_net(struct net *net, unsigned int ip_tnl_net_id,
 				  struct rtnl_link_ops *ops, char *devname)
 {
 	struct ip_tunnel_net *itn = net_generic(net, ip_tnl_net_id);
@@ -1196,7 +1196,7 @@ void ip_tunnel_uninit(struct net_device *dev)
 EXPORT_SYMBOL_GPL(ip_tunnel_uninit);
 
 /* Do least required initialization, rest of init is done in tunnel_init call */
-void ip_tunnel_setup(struct net_device *dev, int net_id)
+void ip_tunnel_setup(struct net_device *dev, unsigned int net_id)
 {
 	struct ip_tunnel *tunnel = netdev_priv(dev);
 	tunnel->ip_tnl_net_id = net_id;
diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c
index 5d7944f394d9..8b14f1404c8f 100644
--- a/net/ipv4/ip_vti.c
+++ b/net/ipv4/ip_vti.c
@@ -46,7 +46,7 @@
 
 static struct rtnl_link_ops vti_link_ops __read_mostly;
 
-static int vti_net_id __read_mostly;
+static unsigned int vti_net_id __read_mostly;
 static int vti_tunnel_init(struct net_device *dev);
 
 static int vti_input(struct sk_buff *skb, int nexthdr, __be32 spi,
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index c9392589c415..79489f017854 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -121,7 +121,7 @@ static bool log_ecn_error = true;
 module_param(log_ecn_error, bool, 0644);
 MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");
 
-static int ipip_net_id __read_mostly;
+static unsigned int ipip_net_id __read_mostly;
 
 static int ipip_tunnel_init(struct net_device *dev);
 static struct rtnl_link_ops ipip_link_ops __read_mostly;
diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c
index 4a9e6db9df8d..e6e206fa86c8 100644
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -62,7 +62,7 @@ struct clusterip_config {
 static const struct file_operations clusterip_proc_fops;
 #endif
 
-static int clusterip_net_id __read_mostly;
+static unsigned int clusterip_net_id __read_mostly;
 
 struct clusterip_net {
 	struct list_head configs;