linux/net
Alexey Dobriyan c7d03a00b5 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>
2016-11-18 10:59:15 -05:00
..
6lowpan 6lowpan: ndisc: no overreact if no short address is available 2016-09-19 20:19:34 +02:00
9p IB/core: add support to create a unsafe global rkey to ib_create_pd 2016-09-23 13:47:44 -04:00
802 net: use core MTU range checking in misc drivers 2016-10-20 14:51:10 -04:00
8021q netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
appletalk appletalk: use IS_ENABLED() instead of checking for built-in or module 2016-09-10 21:19:10 -07:00
atm net: remove MTU limits on a few ether_setup callers 2016-10-21 13:57:50 -04:00
ax25
batman-adv This feature and cleanup patchset includes the following changes: 2016-11-09 22:15:28 -05:00
bluetooth Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-10-30 12:42:58 -04:00
bridge netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
caif netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
can can: bcm: fix warning in bcm_connect/proc_register 2016-10-31 20:48:19 +01:00
ceph libceph: initialize last_linger_id with a large integer 2016-11-10 20:13:08 +01:00
core netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
dcb
dccp Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-11-15 10:54:36 -05:00
decnet net: fix sleeping for sk_wait_event() 2016-11-14 13:17:21 -05:00
dns_resolver
dsa net: remove MTU limits on a few ether_setup callers 2016-10-21 13:57:50 -04:00
ethernet net: make default TX queue length a defined constant 2016-11-07 20:15:55 -05:00
hsr Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-10-30 12:42:58 -04:00
ieee802154 genetlink: mark families as __ro_after_init 2016-10-27 16:16:09 -04:00
ipv4 netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
ipv6 netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
ipx
irda genetlink: mark families as __ro_after_init 2016-10-27 16:16:09 -04:00
iucv Subject: [PATCH] af_iucv: drop skbs rejected by filter 2016-10-12 01:56:04 -04:00
kcm Merge branch 'work.splice_read' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-10-07 15:36:58 -07:00
key netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
l2tp net: l2tp: fix negative assignment to unsigned int 2016-11-09 18:55:36 -05:00
l3mdev net: ipv6: Remove l3mdev_get_saddr6 2016-09-10 23:12:53 -07:00
lapb
llc net: fix sleeping for sk_wait_event() 2016-11-14 13:17:21 -05:00
mac80211 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-10-30 12:42:58 -04:00
mac802154 mac802154: use rate limited warnings for malformed frames 2016-09-19 20:19:34 +02:00
mpls lwt: Remove unused len field 2016-10-23 17:45:01 -04:00
ncsi net/ncsi: Improve HNCDSC AEN handler 2016-10-20 11:23:08 -04:00
netfilter netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
netlabel genetlink: mark families as __ro_after_init 2016-10-27 16:16:09 -04:00
netlink Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-11-15 10:54:36 -05:00
netrom
nfc genetlink: mark families as __ro_after_init 2016-10-27 16:16:09 -04:00
openvswitch netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
packet packet: on direct_xmit, limit tso and csum to supported devices 2016-10-29 15:02:15 -04:00
phonet netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
qrtr
rds netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
rfkill
rose rose: limit sk_filter trim to payload 2016-07-13 11:53:40 -07:00
rxrpc udp: do fwd memory scheduling on dequeue 2016-11-07 13:24:41 -05:00
sched netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
sctp sctp: use new rhlist interface on sctp transport rhashtable 2016-11-16 23:22:17 -05:00
strparser strparser: Propagate correct error code in strp_recv() 2016-10-12 01:51:49 -04:00
sunrpc netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
switchdev Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-10-30 12:42:58 -04:00
tipc netns: make struct pernet_operations::id unsigned int 2016-11-18 10:59:15 -05:00
unix Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-11-15 10:54:36 -05:00
vmw_vsock net: fix sleeping for sk_wait_event() 2016-11-14 13:17:21 -05:00
wimax genetlink: mark families as __ro_after_init 2016-10-27 16:16:09 -04:00
wireless Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-10-30 12:42:58 -04:00
x25 net: x25: remove null checks on arrays calling_ae and called_ae 2016-09-09 18:13:30 -07:00
xfrm Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next 2016-10-28 13:26:27 -04:00
compat.c
Kconfig strparser: Stream parser for messages 2016-08-17 19:36:23 -04:00
Makefile strparser: Stream parser for messages 2016-08-17 19:36:23 -04:00
socket.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-11-15 10:54:36 -05:00
sysctl_net.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2016-10-06 09:52:23 -07:00