From 9679e4dd628743b9ef4375d60ae69923c3766173 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Wed, 15 Oct 2008 22:01:51 -0700 Subject: [PATCH] kernel/sys.c: improve code generation utsname() is quite expensive to calculate. Cache it in a local. text data bss dec hex filename before: 11136 720 16 11872 2e60 kernel/sys.o after: 11096 720 16 11832 2e38 kernel/sys.o Acked-by: Vegard Nossum Cc: "Eric W. Biederman" Acked-by: "Serge E. Hallyn" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/sys.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/kernel/sys.c b/kernel/sys.c index 558b035965aa..0bc8fa3c2288 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1349,9 +1349,10 @@ asmlinkage long sys_sethostname(char __user *name, int len) down_write(&uts_sem); errno = -EFAULT; if (!copy_from_user(tmp, name, len)) { - memcpy(utsname()->nodename, tmp, len); - memset(utsname()->nodename + len, 0, - sizeof(utsname()->nodename) - len); + struct new_utsname *u = utsname(); + + memcpy(u->nodename, tmp, len); + memset(u->nodename + len, 0, sizeof(u->nodename) - len); errno = 0; } up_write(&uts_sem); @@ -1363,15 +1364,17 @@ asmlinkage long sys_sethostname(char __user *name, int len) asmlinkage long sys_gethostname(char __user *name, int len) { int i, errno; + struct new_utsname *u; if (len < 0) return -EINVAL; down_read(&uts_sem); - i = 1 + strlen(utsname()->nodename); + u = utsname(); + i = 1 + strlen(u->nodename); if (i > len) i = len; errno = 0; - if (copy_to_user(name, utsname()->nodename, i)) + if (copy_to_user(name, u->nodename, i)) errno = -EFAULT; up_read(&uts_sem); return errno; @@ -1396,9 +1399,10 @@ asmlinkage long sys_setdomainname(char __user *name, int len) down_write(&uts_sem); errno = -EFAULT; if (!copy_from_user(tmp, name, len)) { - memcpy(utsname()->domainname, tmp, len); - memset(utsname()->domainname + len, 0, - sizeof(utsname()->domainname) - len); + struct new_utsname *u = utsname(); + + memcpy(u->domainname, tmp, len); + memset(u->domainname + len, 0, sizeof(u->domainname) - len); errno = 0; } up_write(&uts_sem); -- 2.20.1