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Commit 9679e4dd authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds
Browse files

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: default avatarVegard Nossum <vegard.nossum@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: default avatar"Serge E. Hallyn" <serue@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 87988815

kernel/sys.c

+12 −8
Original line number Diff line number Diff line
@@ -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);