summaryrefslogtreecommitdiffstats
path: root/fs
diff options
context:
space:
mode:
authorAlexey Dobriyan <adobriyan@gmail.com>2016-11-17 04:58:21 +0300
committerDavid S. Miller <davem@davemloft.net>2016-11-18 10:59:15 -0500
commitc7d03a00b56fc23c3a01a8353789ad257363e281 (patch)
treec4b4b9bbdf0ab8d53c213769052a4875c2866010 /fs
parente68b6e50fa359cc5aad4d2f8ac2bdbc1a8f4fd59 (diff)
downloadlinux-c7d03a00b56fc23c3a01a8353789ad257363e281.tar.bz2
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>
Diffstat (limited to 'fs')
-rw-r--r--fs/lockd/netns.h2
-rw-r--r--fs/lockd/svc.c2
-rw-r--r--fs/nfs/inode.c2
-rw-r--r--fs/nfs/netns.h2
-rw-r--r--fs/nfs_common/grace.c2
-rw-r--r--fs/nfsd/netns.h2
-rw-r--r--fs/nfsd/nfsctl.c2
7 files changed, 7 insertions, 7 deletions
diff --git a/fs/lockd/netns.h b/fs/lockd/netns.h
index 5426189406c1..fb8cac88251a 100644
--- a/fs/lockd/netns.h
+++ b/fs/lockd/netns.h
@@ -15,6 +15,6 @@ struct lockd_net {
struct list_head nsm_handles;
};
-extern int lockd_net_id;
+extern unsigned int lockd_net_id;
#endif
diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index fc4084ef4736..1c13dd80744f 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -57,7 +57,7 @@ static struct task_struct *nlmsvc_task;
static struct svc_rqst *nlmsvc_rqst;
unsigned long nlmsvc_timeout;
-int lockd_net_id;
+unsigned int lockd_net_id;
/*
* These can be set at insmod time (useful for NFS as root filesystem),
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index bf4ec5ecc97e..ce42dd00e4ee 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -2015,7 +2015,7 @@ static void nfsiod_stop(void)
destroy_workqueue(wq);
}
-int nfs_net_id;
+unsigned int nfs_net_id;
EXPORT_SYMBOL_GPL(nfs_net_id);
static int nfs_net_init(struct net *net)
diff --git a/fs/nfs/netns.h b/fs/nfs/netns.h
index fbce0d885d4c..5fbd2bde91ba 100644
--- a/fs/nfs/netns.h
+++ b/fs/nfs/netns.h
@@ -35,6 +35,6 @@ struct nfs_net {
#endif
};
-extern int nfs_net_id;
+extern unsigned int nfs_net_id;
#endif
diff --git a/fs/nfs_common/grace.c b/fs/nfs_common/grace.c
index fd8c9a5bcac4..420d3a0ab258 100644
--- a/fs/nfs_common/grace.c
+++ b/fs/nfs_common/grace.c
@@ -9,7 +9,7 @@
#include <net/netns/generic.h>
#include <linux/fs.h>
-static int grace_net_id;
+static unsigned int grace_net_id;
static DEFINE_SPINLOCK(grace_lock);
/**
diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
index ee36efd5aece..3714231a9d0f 100644
--- a/fs/nfsd/netns.h
+++ b/fs/nfsd/netns.h
@@ -124,5 +124,5 @@ struct nfsd_net {
/* Simple check to find out if a given net was properly initialized */
#define nfsd_netns_ready(nn) ((nn)->sessionid_hashtbl)
-extern int nfsd_net_id;
+extern unsigned int nfsd_net_id;
#endif /* __NFSD_NETNS_H__ */
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 36b2af931e06..2857e46d5cc5 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1201,7 +1201,7 @@ static int create_proc_exports_entry(void)
}
#endif
-int nfsd_net_id;
+unsigned int nfsd_net_id;
static __net_init int nfsd_init_net(struct net *net)
{