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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 <asm/uaccess.h>
/*
* change timeval to jiffies, trying to avoid the
* most obvious overflows..
*
* The tv_*sec values are signed, but nothing seems to
* indicate whether we really should use them as signed values
* when doing itimers. POSIX doesn't mention this (but if
* alarm() uses itimers without checking, we have to use unsigned
* arithmetic).
*/
static unsigned long tvtojiffies(struct timeval *value)
{
unsigned long sec = (unsigned) value->tv_sec;
unsigned long usec = (unsigned) value->tv_usec;
if (sec > (ULONG_MAX / HZ))
return ULONG_MAX;
usec += 1000000 / HZ - 1;
usec /= 1000000 / HZ;
return HZ*sec+usec;
}
static void jiffiestotv(unsigned long jiffies, struct timeval *value)
{
value->tv_usec = (jiffies % HZ) * (1000000 / HZ);
value->tv_sec = jiffies / HZ;
}
int do_getitimer(int which, struct itimerval *value)
{
register unsigned long val, interval;
switch (which) {
case ITIMER_REAL:
interval = current->it_real_incr;
val = 0;
/*
* FIXME! This needs to be atomic, in case the kernel timer happens!
*/
if (timer_pending(¤t->real_timer)) {
val = current->real_timer.expires - jiffies;
/* look out for negative/zero itimer.. */
if ((long) val <= 0)
val = 1;
}
break;
case ITIMER_VIRTUAL:
val = current->it_virt_value;
interval = current->it_virt_incr;
break;
case ITIMER_PROF:
val = current->it_prof_value;
interval = current->it_prof_incr;
break;
default:
return(-EINVAL);
}
jiffiestotv(val, &value->it_value);
jiffiestotv(interval, &value->it_interval);
return 0;
}
/* SMP: Only we modify our itimer values. */
asmlinkage long sys_getitimer(int which, struct itimerval *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 interval;
send_sig(SIGALRM, p, 1);
interval = p->it_real_incr;
if (interval) {
if (interval > (unsigned long) LONG_MAX)
interval = LONG_MAX;
p->real_timer.expires = jiffies + interval;
add_timer(&p->real_timer);
}
}
int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
{
register unsigned long i, j;
int k;
i = tvtojiffies(&value->it_interval);
j = tvtojiffies(&value->it_value);
if (ovalue && (k = do_getitimer(which, ovalue)) < 0)
return k;
switch (which) {
case ITIMER_REAL:
del_timer_sync(¤t->real_timer);
current->it_real_value = j;
current->it_real_incr = i;
if (!j)
break;
if (j > (unsigned long) LONG_MAX)
j = LONG_MAX;
i = j + jiffies;
current->real_timer.expires = i;
add_timer(¤t->real_timer);
break;
case ITIMER_VIRTUAL:
if (j)
j++;
current->it_virt_value = j;
current->it_virt_incr = i;
break;
case ITIMER_PROF:
if (j)
j++;
current->it_prof_value = j;
current->it_prof_incr = i;
break;
default:
return -EINVAL;
}
return 0;
}
/* SMP: Again, only we play with our itimers, and signals are SMP safe
* now so that is not an issue at all anymore.
*/
asmlinkage long sys_setitimer(int which, struct itimerval *value,
struct itimerval *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 : 0);
if (error || !ovalue)
return error;
if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
return -EFAULT;
return 0;
}
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