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>

8 files changed, 8 insertions, 8 deletions

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 89a6b0546804..c68f4fe001d7 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -116,7 +116,7 @@ static LIST_HEAD(dev_list);
 static LIST_HEAD(listen_any_list);
 static DEFINE_MUTEX(lock);
 static struct workqueue_struct *cma_wq;
-static int cma_pernet_id;
+static unsigned int cma_pernet_id;
 
 struct cma_pernet {
 	struct idr tcp_ps;
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 5708f17e4cdf..8029dd4912b6 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -199,7 +199,7 @@ MODULE_PARM_DESC(lp_interval, "The number of seconds between instances where "
 atomic_t netpoll_block_tx = ATOMIC_INIT(0);
 #endif
 
-int bond_net_id __read_mostly;
+unsigned int bond_net_id __read_mostly;
 
 static __be32 arp_target[BOND_MAX_ARP_TARGETS];
 static int arp_ip_count;
diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index 85a423a66478..90dc6b188607 100644
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -43,7 +43,7 @@ struct geneve_net {
 	struct list_head	sock_list;
 };
 
-static int geneve_net_id;
+static unsigned int geneve_net_id;
 
 union geneve_addr {
 	struct sockaddr_in sin;
diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index 719d19f35673..98f10c216521 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -77,7 +77,7 @@ struct gtp_dev {
 	struct hlist_head	*addr_hash;
 };
 
-static int gtp_net_id __read_mostly;
+static unsigned int gtp_net_id __read_mostly;
 
 struct gtp_net {
 	struct list_head gtp_dev_list;
diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 5489c0ec1d9a..3d3b1f4339ef 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -204,7 +204,7 @@ static atomic_t ppp_unit_count = ATOMIC_INIT(0);
 static atomic_t channel_count = ATOMIC_INIT(0);
 
 /* per-net private data for this module */
-static int ppp_net_id __read_mostly;
+static unsigned int ppp_net_id __read_mostly;
 struct ppp_net {
 	/* units to ppp mapping */
 	struct idr units_idr;
diff --git a/drivers/net/ppp/pppoe.c b/drivers/net/ppp/pppoe.c
index 4ddae8118c85..f017c72bb7fd 100644
--- a/drivers/net/ppp/pppoe.c
+++ b/drivers/net/ppp/pppoe.c
@@ -95,7 +95,7 @@ static const struct proto_ops pppoe_ops;
 static const struct ppp_channel_ops pppoe_chan_ops;
 
 /* per-net private data for this module */
-static int pppoe_net_id __read_mostly;
+static unsigned int pppoe_net_id __read_mostly;
 struct pppoe_net {
 	/*
 	 * we could use _single_ hash table for all
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 0a3fd675408f..21e92be6e56c 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -52,7 +52,7 @@ 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 vxlan_net_id;
+static unsigned int vxlan_net_id;
 static struct rtnl_link_ops vxlan_link_ops;
 
 static const u8 all_zeros_mac[ETH_ALEN + 2];
diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index 8f366cc097e6..1293f8494985 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -250,7 +250,7 @@ static inline void hwsim_clear_chanctx_magic(struct ieee80211_chanctx_conf *c)
 	cp->magic = 0;
 }
 
-static int hwsim_net_id;
+static unsigned int hwsim_net_id;
 
 static int hwsim_netgroup;