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 <vegard.nossum@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Acked-by: "Serge E. Hallyn" <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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8798881507
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9679e4dd62
1 changed files with 12 additions and 8 deletions
20
kernel/sys.c
20
kernel/sys.c
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@ -1349,9 +1349,10 @@ asmlinkage long sys_sethostname(char __user *name, int len)
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down_write(&uts_sem);
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errno = -EFAULT;
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if (!copy_from_user(tmp, name, len)) {
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memcpy(utsname()->nodename, tmp, len);
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memset(utsname()->nodename + len, 0,
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sizeof(utsname()->nodename) - len);
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struct new_utsname *u = utsname();
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memcpy(u->nodename, tmp, len);
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memset(u->nodename + len, 0, sizeof(u->nodename) - len);
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errno = 0;
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}
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up_write(&uts_sem);
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@ -1363,15 +1364,17 @@ asmlinkage long sys_sethostname(char __user *name, int len)
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asmlinkage long sys_gethostname(char __user *name, int len)
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{
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int i, errno;
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struct new_utsname *u;
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if (len < 0)
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return -EINVAL;
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down_read(&uts_sem);
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i = 1 + strlen(utsname()->nodename);
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u = utsname();
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i = 1 + strlen(u->nodename);
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if (i > len)
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i = len;
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errno = 0;
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if (copy_to_user(name, utsname()->nodename, i))
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if (copy_to_user(name, u->nodename, i))
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errno = -EFAULT;
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up_read(&uts_sem);
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return errno;
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@ -1396,9 +1399,10 @@ asmlinkage long sys_setdomainname(char __user *name, int len)
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down_write(&uts_sem);
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errno = -EFAULT;
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if (!copy_from_user(tmp, name, len)) {
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memcpy(utsname()->domainname, tmp, len);
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memset(utsname()->domainname + len, 0,
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sizeof(utsname()->domainname) - len);
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struct new_utsname *u = utsname();
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memcpy(u->domainname, tmp, len);
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memset(u->domainname + len, 0, sizeof(u->domainname) - len);
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errno = 0;
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}
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up_write(&uts_sem);
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