From c7d03a00b56fc23c3a01a8353789ad257363e281 Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Thu, 17 Nov 2016 04:58:21 +0300 Subject: 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 Signed-off-by: David S. Miller --- drivers/infiniband/core/cma.c | 2 +- drivers/net/bonding/bond_main.c | 2 +- drivers/net/geneve.c | 2 +- drivers/net/gtp.c | 2 +- drivers/net/ppp/ppp_generic.c | 2 +- drivers/net/ppp/pppoe.c | 2 +- drivers/net/vxlan.c | 2 +- drivers/net/wireless/mac80211_hwsim.c | 2 +- 8 files changed, 8 insertions(+), 8 deletions(-) (limited to 'drivers') 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; -- cgit v1.2.3