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tag: v2.6.15-rc7
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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/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/syscalls.h>
#include <linux/time.h>
#include <linux/posix-timers.h>

#include <asm/uaccess.h>

static unsigned long it_real_value(struct signal_struct *sig)
{
unsigned long val = 0;
if (timer_pending(&sig->real_timer)) {
val = sig->real_timer.expires - jiffies;

/* look out for negative/zero itimer.. */
if ((long) val <= 0)
val = 1;
}
return val;
}

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

switch (which) {
case ITIMER_REAL:
spin_lock_irq(&tsk->sighand->siglock);
interval = tsk->signal->it_real_incr;
val = it_real_value(tsk->signal);
spin_unlock_irq(&tsk->sighand->siglock);
jiffies_to_timeval(val, &value->it_value);
jiffies_to_timeval(interval, &value->it_interval);
break;
case ITIMER_VIRTUAL:
read_lock(&tasklist_lock);
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_struct *t = tsk;
cputime_t utime = tsk->signal->utime;
do {
utime = cputime_add(utime, t->utime);
t = next_thread(t);
} while (t != tsk);
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);
read_unlock(&tasklist_lock);
cputime_to_timeval(cval, &value->it_value);
cputime_to_timeval(cinterval, &value->it_interval);
break;
case ITIMER_PROF:
read_lock(&tasklist_lock);
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_struct *t = tsk;
cputime_t ptime = cputime_add(tsk->signal->utime,
tsk->signal->stime);
do {
ptime = cputime_add(ptime,
cputime_add(t->utime,
t->stime));
t = next_thread(t);
} while (t != tsk);
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);
read_unlock(&tasklist_lock);
cputime_to_timeval(cval, &value->it_value);
cputime_to_timeval(cinterval, &value->it_interval);
break;
default:
return(-EINVAL);
}
return 0;
}

asmlinkage long sys_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;
}


void it_real_fn(unsigned long __data)
{
struct task_struct * p = (struct task_struct *) __data;
unsigned long inc = p->signal->it_real_incr;

send_group_sig_info(SIGALRM, SEND_SIG_PRIV, p);

/*
* Now restart the timer if necessary. We don't need any locking
* here because do_setitimer makes sure we have finished running
* before it touches anything.
* Note, we KNOW we are (or should be) at a jiffie edge here so
* we don't need the +1 stuff. Also, we want to use the prior
* expire value so as to not "slip" a jiffie if we are late.
* Deal with requesting a time prior to "now" here rather than
* in add_timer.
*/
if (!inc)
return;
while (time_before_eq(p->signal->real_timer.expires, jiffies))
p->signal->real_timer.expires += inc;
add_timer(&p->signal->real_timer);
}

int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
{
struct task_struct *tsk = current;
  unsigned long val, interval, expires;
cputime_t cval, cinterval, nval, ninterval;

switch (which) {
case ITIMER_REAL:
again:
spin_lock_irq(&tsk->sighand->siglock);
interval = tsk->signal->it_real_incr;
val = it_real_value(tsk->signal);
/* We are sharing ->siglock with it_real_fn() */
if (try_to_del_timer_sync(&tsk->signal->real_timer) < 0) {
spin_unlock_irq(&tsk->sighand->siglock);
goto again;
}
tsk->signal->it_real_incr =
timeval_to_jiffies(&value->it_interval);
expires = timeval_to_jiffies(&value->it_value);
if (expires)
mod_timer(&tsk->signal->real_timer,
jiffies + 1 + expires);
spin_unlock_irq(&tsk->sighand->siglock);
if (ovalue) {
jiffies_to_timeval(val, &ovalue->it_value);
jiffies_to_timeval(interval,
&ovalue->it_interval);
}
break;
case ITIMER_VIRTUAL:
nval = timeval_to_cputime(&value->it_value);
ninterval = timeval_to_cputime(&value->it_interval);
read_lock(&tasklist_lock);
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);
read_unlock(&tasklist_lock);
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);
read_lock(&tasklist_lock);
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);
read_unlock(&tasklist_lock);
if (ovalue) {
cputime_to_timeval(cval, &ovalue->it_value);
cputime_to_timeval(cinterval, &ovalue->it_interval);
}
break;
default:
return -EINVAL;
}
return 0;
}

asmlinkage long sys_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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