forked from Minki/linux
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>
133 lines
3.0 KiB
C
133 lines
3.0 KiB
C
/*
|
|
* Common code for control of lockd and nfsv4 grace periods.
|
|
*
|
|
* Transplanted from lockd code
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <net/net_namespace.h>
|
|
#include <net/netns/generic.h>
|
|
#include <linux/fs.h>
|
|
|
|
static unsigned int grace_net_id;
|
|
static DEFINE_SPINLOCK(grace_lock);
|
|
|
|
/**
|
|
* locks_start_grace
|
|
* @net: net namespace that this lock manager belongs to
|
|
* @lm: who this grace period is for
|
|
*
|
|
* A grace period is a period during which locks should not be given
|
|
* out. Currently grace periods are only enforced by the two lock
|
|
* managers (lockd and nfsd), using the locks_in_grace() function to
|
|
* check when they are in a grace period.
|
|
*
|
|
* This function is called to start a grace period.
|
|
*/
|
|
void
|
|
locks_start_grace(struct net *net, struct lock_manager *lm)
|
|
{
|
|
struct list_head *grace_list = net_generic(net, grace_net_id);
|
|
|
|
spin_lock(&grace_lock);
|
|
list_add(&lm->list, grace_list);
|
|
spin_unlock(&grace_lock);
|
|
}
|
|
EXPORT_SYMBOL_GPL(locks_start_grace);
|
|
|
|
/**
|
|
* locks_end_grace
|
|
* @net: net namespace that this lock manager belongs to
|
|
* @lm: who this grace period is for
|
|
*
|
|
* Call this function to state that the given lock manager is ready to
|
|
* resume regular locking. The grace period will not end until all lock
|
|
* managers that called locks_start_grace() also call locks_end_grace().
|
|
* Note that callers count on it being safe to call this more than once,
|
|
* and the second call should be a no-op.
|
|
*/
|
|
void
|
|
locks_end_grace(struct lock_manager *lm)
|
|
{
|
|
spin_lock(&grace_lock);
|
|
list_del_init(&lm->list);
|
|
spin_unlock(&grace_lock);
|
|
}
|
|
EXPORT_SYMBOL_GPL(locks_end_grace);
|
|
|
|
/**
|
|
* locks_in_grace
|
|
*
|
|
* Lock managers call this function to determine when it is OK for them
|
|
* to answer ordinary lock requests, and when they should accept only
|
|
* lock reclaims.
|
|
*/
|
|
int
|
|
__state_in_grace(struct net *net, bool open)
|
|
{
|
|
struct list_head *grace_list = net_generic(net, grace_net_id);
|
|
struct lock_manager *lm;
|
|
|
|
if (!open)
|
|
return !list_empty(grace_list);
|
|
|
|
list_for_each_entry(lm, grace_list, list) {
|
|
if (lm->block_opens)
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
int locks_in_grace(struct net *net)
|
|
{
|
|
return __state_in_grace(net, 0);
|
|
}
|
|
EXPORT_SYMBOL_GPL(locks_in_grace);
|
|
|
|
int opens_in_grace(struct net *net)
|
|
{
|
|
return __state_in_grace(net, 1);
|
|
}
|
|
EXPORT_SYMBOL_GPL(opens_in_grace);
|
|
|
|
static int __net_init
|
|
grace_init_net(struct net *net)
|
|
{
|
|
struct list_head *grace_list = net_generic(net, grace_net_id);
|
|
|
|
INIT_LIST_HEAD(grace_list);
|
|
return 0;
|
|
}
|
|
|
|
static void __net_exit
|
|
grace_exit_net(struct net *net)
|
|
{
|
|
struct list_head *grace_list = net_generic(net, grace_net_id);
|
|
|
|
BUG_ON(!list_empty(grace_list));
|
|
}
|
|
|
|
static struct pernet_operations grace_net_ops = {
|
|
.init = grace_init_net,
|
|
.exit = grace_exit_net,
|
|
.id = &grace_net_id,
|
|
.size = sizeof(struct list_head),
|
|
};
|
|
|
|
static int __init
|
|
init_grace(void)
|
|
{
|
|
return register_pernet_subsys(&grace_net_ops);
|
|
}
|
|
|
|
static void __exit
|
|
exit_grace(void)
|
|
{
|
|
unregister_pernet_subsys(&grace_net_ops);
|
|
}
|
|
|
|
MODULE_AUTHOR("Jeff Layton <jlayton@primarydata.com>");
|
|
MODULE_LICENSE("GPL");
|
|
module_init(init_grace)
|
|
module_exit(exit_grace)
|