Commit f1f1d5eb authored by Richard Cochran's avatar Richard Cochran Committed by Thomas Gleixner
Browse files

posix-timers: Introduce a syscall for clock tuning. 



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: default avatarRichard Cochran <richard.cochran@omicron.at>
Acked-by: default avatarJohn Stultz <johnstul@us.ibm.com>
LKML-Reference: <20110201134419.869804645@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 65f5d80b

include/linux/posix-timers.h

+2 −0
Original line number Diff line number Diff line
@@ -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 *);

include/linux/syscalls.h

+2 −0
Original line number Diff line number Diff line
@@ -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,

kernel/compat.c

+23 −0
Original line number Diff line number Diff line
@@ -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)

{

kernel/posix-timers.c

+30 −0
Original line number Diff line number Diff line
@@ -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)

{

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