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c7d03a00b5
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>
137 lines
2.6 KiB
C
137 lines
2.6 KiB
C
/*
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* linux/net/sunrpc/sunrpc_syms.c
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*
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* Symbols exported by the sunrpc module.
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*
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* Copyright (C) 1997 Olaf Kirch <okir@monad.swb.de>
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/uio.h>
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#include <linux/unistd.h>
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#include <linux/init.h>
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#include <linux/sunrpc/sched.h>
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#include <linux/sunrpc/clnt.h>
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#include <linux/sunrpc/svc.h>
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#include <linux/sunrpc/svcsock.h>
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#include <linux/sunrpc/auth.h>
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#include <linux/workqueue.h>
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#include <linux/sunrpc/rpc_pipe_fs.h>
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#include <linux/sunrpc/xprtsock.h>
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#include "netns.h"
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unsigned int sunrpc_net_id;
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EXPORT_SYMBOL_GPL(sunrpc_net_id);
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static __net_init int sunrpc_init_net(struct net *net)
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{
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int err;
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struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
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err = rpc_proc_init(net);
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if (err)
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goto err_proc;
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err = ip_map_cache_create(net);
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if (err)
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goto err_ipmap;
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err = unix_gid_cache_create(net);
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if (err)
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goto err_unixgid;
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err = rpc_pipefs_init_net(net);
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if (err)
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goto err_pipefs;
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INIT_LIST_HEAD(&sn->all_clients);
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spin_lock_init(&sn->rpc_client_lock);
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spin_lock_init(&sn->rpcb_clnt_lock);
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return 0;
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err_pipefs:
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unix_gid_cache_destroy(net);
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err_unixgid:
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ip_map_cache_destroy(net);
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err_ipmap:
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rpc_proc_exit(net);
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err_proc:
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return err;
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}
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static __net_exit void sunrpc_exit_net(struct net *net)
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{
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rpc_pipefs_exit_net(net);
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unix_gid_cache_destroy(net);
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ip_map_cache_destroy(net);
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rpc_proc_exit(net);
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}
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static struct pernet_operations sunrpc_net_ops = {
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.init = sunrpc_init_net,
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.exit = sunrpc_exit_net,
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.id = &sunrpc_net_id,
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.size = sizeof(struct sunrpc_net),
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};
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static int __init
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init_sunrpc(void)
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{
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int err = rpc_init_mempool();
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if (err)
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goto out;
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err = rpcauth_init_module();
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if (err)
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goto out2;
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cache_initialize();
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err = register_pernet_subsys(&sunrpc_net_ops);
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if (err)
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goto out3;
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err = register_rpc_pipefs();
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if (err)
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goto out4;
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sunrpc_debugfs_init();
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#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
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rpc_register_sysctl();
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#endif
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svc_init_xprt_sock(); /* svc sock transport */
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init_socket_xprt(); /* clnt sock transport */
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return 0;
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out4:
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unregister_pernet_subsys(&sunrpc_net_ops);
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out3:
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rpcauth_remove_module();
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out2:
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rpc_destroy_mempool();
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out:
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return err;
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}
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static void __exit
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cleanup_sunrpc(void)
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{
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rpcauth_remove_module();
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cleanup_socket_xprt();
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svc_cleanup_xprt_sock();
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sunrpc_debugfs_exit();
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unregister_rpc_pipefs();
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rpc_destroy_mempool();
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unregister_pernet_subsys(&sunrpc_net_ops);
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#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
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rpc_unregister_sysctl();
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#endif
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rcu_barrier(); /* Wait for completion of call_rcu()'s */
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}
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MODULE_LICENSE("GPL");
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fs_initcall(init_sunrpc); /* Ensure we're initialised before nfs */
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module_exit(cleanup_sunrpc);
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