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tag: v2.6.18
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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 <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:
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;
}


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

send_group_sig_info(SIGALRM, SEND_SIG_PRIV, sig->tsk);

if (sig->it_real_incr.tv64 != 0) {
hrtimer_forward(timer, timer->base->softirq_time,
sig->it_real_incr);
return HRTIMER_RESTART;
}
return HRTIMER_NORESTART;
}

/*
* We do not care about correctness. We just sanitize the values so
* the ktime_t operations which expect normalized values do not
* break. This converts negative values to long timeouts similar to
* the code in kernel versions < 2.6.16
*
* Print a limited number of warning messages when an invalid timeval
* is detected.
*/
static void fixup_timeval(struct timeval *tv, int interval)
{
static int warnlimit = 10;
unsigned long tmp;

if (warnlimit > 0) {
warnlimit--;
printk(KERN_WARNING
"setitimer: %s (pid = %d) provided "
"invalid timeval %s: tv_sec = %ld tv_usec = %ld\n",
current->comm, current->pid,
interval ? "it_interval" : "it_value",
tv->tv_sec, (long) tv->tv_usec);
}

tmp = tv->tv_usec;
if (tmp >= USEC_PER_SEC) {
tv->tv_usec = tmp % USEC_PER_SEC;
tv->tv_sec += tmp / USEC_PER_SEC;
}

tmp = tv->tv_sec;
if (tmp > LONG_MAX)
tv->tv_sec = LONG_MAX;
}

/*
* 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))

/*
* Check for invalid timevals, sanitize them and print a limited
* number of warnings.
*/
static void check_itimerval(struct itimerval *value) {

if (unlikely(!timeval_valid(&value->it_value)))
fixup_timeval(&value->it_value, 0);

if (unlikely(!timeval_valid(&value->it_interval)))
fixup_timeval(&value->it_interval, 1);
}

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.
*
* Note: Although the spec requires that invalid values shall
* return -EINVAL, we just fixup the value and print a limited
* number of warnings in order not to break users of this
* historical misfeature.
*
* Scheduled for replacement in March 2007
*/
check_itimerval(value);

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;
}
tsk->signal->it_real_incr =
timeval_to_ktime(value->it_interval);
expires = timeval_to_ktime(value->it_value);
if (expires.tv64 != 0)
hrtimer_start(timer, expires, HRTIMER_REL);
spin_unlock_irq(&tsk->sighand->siglock);
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;
}

/**
* 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;
}

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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