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tag: v2.6.29-rc5
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/*
* linux/kernel/itimer.c
*
* Copyright (C) 1992 Darren Senn
*/

/* These are all the functions necessary to implement itimers */

#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/syscalls.h>
#include <linux/time.h>
#include <linux/posix-timers.h>
#include <linux/hrtimer.h>

#include <asm/uaccess.h>

/**
* itimer_get_remtime - get remaining time for the timer
*
* @timer: the timer to read
*
* Returns the delta between the expiry time and now, which can be
* less than zero or 1usec for an pending expired timer
*/
static struct timeval itimer_get_remtime(struct hrtimer *timer)
{
ktime_t rem = hrtimer_get_remaining(timer);

/*
* Racy but safe: if the itimer expires after the above
* hrtimer_get_remtime() call but before this condition
* then we return 0 - which is correct.
*/
if (hrtimer_active(timer)) {
if (rem.tv64 <= 0)
rem.tv64 = NSEC_PER_USEC;
} else
rem.tv64 = 0;

return ktime_to_timeval(rem);
}

int do_getitimer(int which, struct itimerval *value)
{
struct task_struct *tsk = current;
cputime_t cinterval, cval;

switch (which) {
case ITIMER_REAL:
spin_lock_irq(&tsk->sighand->siglock);
value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
value->it_interval =
ktime_to_timeval(tsk->signal->it_real_incr);
spin_unlock_irq(&tsk->sighand->siglock);
break;
case ITIMER_VIRTUAL:
spin_lock_irq(&tsk->sighand->siglock);
cval = tsk->signal->it_virt_expires;
cinterval = tsk->signal->it_virt_incr;
if (!cputime_eq(cval, cputime_zero)) {
struct task_cputime cputime;
cputime_t utime;

thread_group_cputimer(tsk, &cputime);
utime = cputime.utime;
if (cputime_le(cval, utime)) { /* about to fire */
cval = jiffies_to_cputime(1);
} else {
cval = cputime_sub(cval, utime);
}
}
spin_unlock_irq(&tsk->sighand->siglock);
cputime_to_timeval(cval, &value->it_value);
cputime_to_timeval(cinterval, &value->it_interval);
break;
case ITIMER_PROF:
spin_lock_irq(&tsk->sighand->siglock);
cval = tsk->signal->it_prof_expires;
cinterval = tsk->signal->it_prof_incr;
if (!cputime_eq(cval, cputime_zero)) {
struct task_cputime times;
cputime_t ptime;

thread_group_cputimer(tsk, &times);
ptime = cputime_add(times.utime, times.stime);
if (cputime_le(cval, ptime)) { /* about to fire */
cval = jiffies_to_cputime(1);
} else {
cval = cputime_sub(cval, ptime);
}
}
spin_unlock_irq(&tsk->sighand->siglock);
cputime_to_timeval(cval, &value->it_value);
cputime_to_timeval(cinterval, &value->it_interval);
break;
default:
return(-EINVAL);
}
return 0;
}

SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
{
int error = -EFAULT;
struct itimerval get_buffer;

if (value) {
error = do_getitimer(which, &get_buffer);
if (!error &&
copy_to_user(value, &get_buffer, sizeof(get_buffer)))
error = -EFAULT;
}
return error;
}


/*
* The timer is automagically restarted, when interval != 0
*/
enum hrtimer_restart it_real_fn(struct hrtimer *timer)
{
struct signal_struct *sig =
container_of(timer, struct signal_struct, real_timer);

kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);

return HRTIMER_NORESTART;
}

/*
* Returns true if the timeval is in canonical form
*/
#define timeval_valid(t) \
(((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))

int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
{
struct task_struct *tsk = current;
struct hrtimer *timer;
ktime_t expires;
cputime_t cval, cinterval, nval, ninterval;

/*
* Validate the timevals in value.
*/
if (!timeval_valid(&value->it_value) ||
!timeval_valid(&value->it_interval))
return -EINVAL;

switch (which) {
case ITIMER_REAL:
again:
spin_lock_irq(&tsk->sighand->siglock);
timer = &tsk->signal->real_timer;
if (ovalue) {
ovalue->it_value = itimer_get_remtime(timer);
ovalue->it_interval
= ktime_to_timeval(tsk->signal->it_real_incr);
}
/* We are sharing ->siglock with it_real_fn() */
if (hrtimer_try_to_cancel(timer) < 0) {
spin_unlock_irq(&tsk->sighand->siglock);
goto again;
}
expires = timeval_to_ktime(value->it_value);
if (expires.tv64 != 0) {
tsk->signal->it_real_incr =
timeval_to_ktime(value->it_interval);
hrtimer_start(timer, expires, HRTIMER_MODE_REL);
} else
tsk->signal->it_real_incr.tv64 = 0;

spin_unlock_irq(&tsk->sighand->siglock);
break;
case ITIMER_VIRTUAL:
nval = timeval_to_cputime(&value->it_value);
ninterval = timeval_to_cputime(&value->it_interval);
spin_lock_irq(&tsk->sighand->siglock);
cval = tsk->signal->it_virt_expires;
cinterval = tsk->signal->it_virt_incr;
if (!cputime_eq(cval, cputime_zero) ||
!cputime_eq(nval, cputime_zero)) {
if (cputime_gt(nval, cputime_zero))
nval = cputime_add(nval,
jiffies_to_cputime(1));
set_process_cpu_timer(tsk, CPUCLOCK_VIRT,
&nval, &cval);
}
tsk->signal->it_virt_expires = nval;
tsk->signal->it_virt_incr = ninterval;
spin_unlock_irq(&tsk->sighand->siglock);
if (ovalue) {
cputime_to_timeval(cval, &ovalue->it_value);
cputime_to_timeval(cinterval, &ovalue->it_interval);
}
break;
case ITIMER_PROF:
nval = timeval_to_cputime(&value->it_value);
ninterval = timeval_to_cputime(&value->it_interval);
spin_lock_irq(&tsk->sighand->siglock);
cval = tsk->signal->it_prof_expires;
cinterval = tsk->signal->it_prof_incr;
if (!cputime_eq(cval, cputime_zero) ||
!cputime_eq(nval, cputime_zero)) {
if (cputime_gt(nval, cputime_zero))
nval = cputime_add(nval,
jiffies_to_cputime(1));
set_process_cpu_timer(tsk, CPUCLOCK_PROF,
&nval, &cval);
}
tsk->signal->it_prof_expires = nval;
tsk->signal->it_prof_incr = ninterval;
spin_unlock_irq(&tsk->sighand->siglock);
if (ovalue) {
cputime_to_timeval(cval, &ovalue->it_value);
cputime_to_timeval(cinterval, &ovalue->it_interval);
}
break;
default:
return -EINVAL;
}
return 0;
}

/**
* alarm_setitimer - set alarm in seconds
*
* @seconds: number of seconds until alarm
* 0 disables the alarm
*
* Returns the remaining time in seconds of a pending timer or 0 when
* the timer is not active.
*
* On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
* negative timeval settings which would cause immediate expiry.
*/
unsigned int alarm_setitimer(unsigned int seconds)
{
struct itimerval it_new, it_old;

#if BITS_PER_LONG < 64
if (seconds > INT_MAX)
seconds = INT_MAX;
#endif
it_new.it_value.tv_sec = seconds;
it_new.it_value.tv_usec = 0;
it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;

do_setitimer(ITIMER_REAL, &it_new, &it_old);

/*
* We can't return 0 if we have an alarm pending ... And we'd
* better return too much than too little anyway
*/
if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
it_old.it_value.tv_usec >= 500000)
it_old.it_value.tv_sec++;

return it_old.it_value.tv_sec;
}

SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
struct itimerval __user *, ovalue)
{
struct itimerval set_buffer, get_buffer;
int error;

if (value) {
if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
return -EFAULT;
} else
memset((char *) &set_buffer, 0, sizeof(set_buffer));

error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
if (error || !ovalue)
return error;

if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
return -EFAULT;
return 0;
}
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