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>
diff --git a/net/sched/act_bpf.c b/net/sched/act_bpf.c
index 9ff06cf..1aa4ecf 100644
--- a/net/sched/act_bpf.c
+++ b/net/sched/act_bpf.c
@@ -33,7 +33,7 @@ struct tcf_bpf_cfg {
bool is_ebpf;
};
-static int bpf_net_id;
+static unsigned int bpf_net_id;
static struct tc_action_ops act_bpf_ops;
static int tcf_bpf(struct sk_buff *skb, const struct tc_action *act,
diff --git a/net/sched/act_connmark.c b/net/sched/act_connmark.c
index eae07a2..ab80629 100644
--- a/net/sched/act_connmark.c
+++ b/net/sched/act_connmark.c
@@ -30,7 +30,7 @@
#define CONNMARK_TAB_MASK 3
-static int connmark_net_id;
+static unsigned int connmark_net_id;
static struct tc_action_ops act_connmark_ops;
static int tcf_connmark(struct sk_buff *skb, const struct tc_action *a,
diff --git a/net/sched/act_csum.c b/net/sched/act_csum.c
index e0defce..a0edd80 100644
--- a/net/sched/act_csum.c
+++ b/net/sched/act_csum.c
@@ -42,7 +42,7 @@ static const struct nla_policy csum_policy[TCA_CSUM_MAX + 1] = {
[TCA_CSUM_PARMS] = { .len = sizeof(struct tc_csum), },
};
-static int csum_net_id;
+static unsigned int csum_net_id;
static struct tc_action_ops act_csum_ops;
static int tcf_csum_init(struct net *net, struct nlattr *nla,
diff --git a/net/sched/act_gact.c b/net/sched/act_gact.c
index e0aa30f..e6c874a 100644
--- a/net/sched/act_gact.c
+++ b/net/sched/act_gact.c
@@ -25,7 +25,7 @@
#define GACT_TAB_MASK 15
-static int gact_net_id;
+static unsigned int gact_net_id;
static struct tc_action_ops act_gact_ops;
#ifdef CONFIG_GACT_PROB
diff --git a/net/sched/act_ife.c b/net/sched/act_ife.c
index 95c463c..80b848d 100644
--- a/net/sched/act_ife.c
+++ b/net/sched/act_ife.c
@@ -35,7 +35,7 @@
#define IFE_TAB_MASK 15
-static int ife_net_id;
+static unsigned int ife_net_id;
static int max_metacnt = IFE_META_MAX + 1;
static struct tc_action_ops act_ife_ops;
diff --git a/net/sched/act_ipt.c b/net/sched/act_ipt.c
index ce7ea6c..992ef8d 100644
--- a/net/sched/act_ipt.c
+++ b/net/sched/act_ipt.c
@@ -30,10 +30,10 @@
#define IPT_TAB_MASK 15
-static int ipt_net_id;
+static unsigned int ipt_net_id;
static struct tc_action_ops act_ipt_ops;
-static int xt_net_id;
+static unsigned int xt_net_id;
static struct tc_action_ops act_xt_ops;
static int ipt_init_target(struct xt_entry_target *t, char *table,
diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index 6073a11..b2d417b 100644
--- a/net/sched/act_mirred.c
+++ b/net/sched/act_mirred.c
@@ -70,7 +70,7 @@ static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
[TCA_MIRRED_PARMS] = { .len = sizeof(struct tc_mirred) },
};
-static int mirred_net_id;
+static unsigned int mirred_net_id;
static struct tc_action_ops act_mirred_ops;
static bool dev_is_mac_header_xmit(const struct net_device *dev)
diff --git a/net/sched/act_nat.c b/net/sched/act_nat.c
index 8e8b0cc..9b6aec6 100644
--- a/net/sched/act_nat.c
+++ b/net/sched/act_nat.c
@@ -31,7 +31,7 @@
#define NAT_TAB_MASK 15
-static int nat_net_id;
+static unsigned int nat_net_id;
static struct tc_action_ops act_nat_ops;
static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
diff --git a/net/sched/act_pedit.c b/net/sched/act_pedit.c
index b54d56d..eda3220 100644
--- a/net/sched/act_pedit.c
+++ b/net/sched/act_pedit.c
@@ -25,7 +25,7 @@
#define PEDIT_TAB_MASK 15
-static int pedit_net_id;
+static unsigned int pedit_net_id;
static struct tc_action_ops act_pedit_ops;
static const struct nla_policy pedit_policy[TCA_PEDIT_MAX + 1] = {
diff --git a/net/sched/act_police.c b/net/sched/act_police.c
index d1bd248..c990b73 100644
--- a/net/sched/act_police.c
+++ b/net/sched/act_police.c
@@ -55,7 +55,7 @@ struct tc_police_compat {
/* Each policer is serialized by its individual spinlock */
-static int police_net_id;
+static unsigned int police_net_id;
static struct tc_action_ops act_police_ops;
static int tcf_act_police_walker(struct net *net, struct sk_buff *skb,
diff --git a/net/sched/act_simple.c b/net/sched/act_simple.c
index 289af6f..823a73a 100644
--- a/net/sched/act_simple.c
+++ b/net/sched/act_simple.c
@@ -26,7 +26,7 @@
#define SIMP_TAB_MASK 7
-static int simp_net_id;
+static unsigned int simp_net_id;
static struct tc_action_ops act_simp_ops;
#define SIMP_MAX_DATA 32
diff --git a/net/sched/act_skbedit.c b/net/sched/act_skbedit.c
index 024f3a3..06ccae3 100644
--- a/net/sched/act_skbedit.c
+++ b/net/sched/act_skbedit.c
@@ -29,7 +29,7 @@
#define SKBEDIT_TAB_MASK 15
-static int skbedit_net_id;
+static unsigned int skbedit_net_id;
static struct tc_action_ops act_skbedit_ops;
static int tcf_skbedit(struct sk_buff *skb, const struct tc_action *a,
diff --git a/net/sched/act_skbmod.c b/net/sched/act_skbmod.c
index e7d9638..3b7074e 100644
--- a/net/sched/act_skbmod.c
+++ b/net/sched/act_skbmod.c
@@ -22,7 +22,7 @@
#define SKBMOD_TAB_MASK 15
-static int skbmod_net_id;
+static unsigned int skbmod_net_id;
static struct tc_action_ops act_skbmod_ops;
#define MAX_EDIT_LEN ETH_HLEN
diff --git a/net/sched/act_tunnel_key.c b/net/sched/act_tunnel_key.c
index edc720f..7af7125 100644
--- a/net/sched/act_tunnel_key.c
+++ b/net/sched/act_tunnel_key.c
@@ -22,7 +22,7 @@
#define TUNNEL_KEY_TAB_MASK 15
-static int tunnel_key_net_id;
+static unsigned int tunnel_key_net_id;
static struct tc_action_ops act_tunnel_key_ops;
static int tunnel_key_act(struct sk_buff *skb, const struct tc_action *a,
diff --git a/net/sched/act_vlan.c b/net/sched/act_vlan.c
index b57fcbc..19e0dba 100644
--- a/net/sched/act_vlan.c
+++ b/net/sched/act_vlan.c
@@ -21,7 +21,7 @@
#define VLAN_TAB_MASK 15
-static int vlan_net_id;
+static unsigned int vlan_net_id;
static struct tc_action_ops act_vlan_ops;
static int tcf_vlan(struct sk_buff *skb, const struct tc_action *a,