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posix-timers: Introduce a syscall for clock tuning.

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A new syscall is introduced that allows tuning of a POSIX clock. The
new call, clock_adjtime, takes two parameters, the clock ID and a
pointer to a struct timex. Any ADJTIMEX(2) operation may be requested
via this system call, but various POSIX clocks may or may not support
tuning.

[ tglx: Adapted to the posix-timer cleanup series. Avoid copy_to_user
  	in the error case ]

Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Acked-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <20110201134419.869804645@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Richard Cochran 2011-02-01 13:52:26 +00:00 committed by Thomas Gleixner
parent 65f5d80bdf
commit f1f1d5ebd1
4 changed files with 57 additions and 0 deletions
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2
include/linux/posix-timers.h
View file

@ -4,6 +4,7 @@
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/sched.h>
#include <linux/timex.h>
union cpu_time_count {
cputime_t cpu;
@ -71,6 +72,7 @@ struct k_clock {
int (*clock_set) (const clockid_t which_clock,
const struct timespec *tp);
int (*clock_get) (const clockid_t which_clock, struct timespec * tp);
int (*clock_adj) (const clockid_t which_clock, struct timex *tx);
int (*timer_create) (struct k_itimer *timer);
int (*nsleep) (const clockid_t which_clock, int flags,
struct timespec *, struct timespec __user *);

2
include/linux/syscalls.h
View file

@ -311,6 +311,8 @@ asmlinkage long sys_clock_settime(clockid_t which_clock,
const struct timespec __user *tp);
asmlinkage long sys_clock_gettime(clockid_t which_clock,
struct timespec __user *tp);
asmlinkage long sys_clock_adjtime(clockid_t which_clock,
struct timex __user *tx);
asmlinkage long sys_clock_getres(clockid_t which_clock,
struct timespec __user *tp);
asmlinkage long sys_clock_nanosleep(clockid_t which_clock, int flags,

23
kernel/compat.c
View file

@ -675,6 +675,29 @@ long compat_sys_clock_gettime(clockid_t which_clock,
return err;
}
long compat_sys_clock_adjtime(clockid_t which_clock,
struct compat_timex __user *utp)
{
struct timex txc;
mm_segment_t oldfs;
int err, ret;
err = compat_get_timex(&txc, utp);
if (err)
return err;
oldfs = get_fs();
set_fs(KERNEL_DS);
ret = sys_clock_adjtime(which_clock, (struct timex __user *) &txc);
set_fs(oldfs);
err = compat_put_timex(utp, &txc);
if (err)
return err;
return ret;
}
long compat_sys_clock_getres(clockid_t which_clock,
struct compat_timespec __user *tp)
{

30
kernel/posix-timers.c
View file

@ -170,6 +170,12 @@ static int posix_clock_realtime_set(const clockid_t which_clock,
return do_sys_settimeofday(tp, NULL);
}
static int posix_clock_realtime_adj(const clockid_t which_clock,
struct timex *t)
{
return do_adjtimex(t);
}
/*
* Get monotonic time for posix timers
*/
@ -216,6 +222,7 @@ static __init int init_posix_timers(void)
.clock_getres = hrtimer_get_res,
.clock_get = posix_clock_realtime_get,
.clock_set = posix_clock_realtime_set,
.clock_adj = posix_clock_realtime_adj,
.nsleep = common_nsleep,
.nsleep_restart = hrtimer_nanosleep_restart,
.timer_create = common_timer_create,
@ -948,6 +955,29 @@ SYSCALL_DEFINE2(clock_gettime, const clockid_t, which_clock,
return error;
}
SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
struct timex __user *, utx)
{
struct k_clock *kc = clockid_to_kclock(which_clock);
struct timex ktx;
int err;
if (!kc)
return -EINVAL;
if (!kc->clock_adj)
return -EOPNOTSUPP;
if (copy_from_user(&ktx, utx, sizeof(ktx)))
return -EFAULT;
err = kc->clock_adj(which_clock, &ktx);
if (!err && copy_to_user(utx, &ktx, sizeof(ktx)))
return -EFAULT;
return err;
}
SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
struct timespec __user *, tp)
{