kernel/itimer.c - maze/linux - Git at Google

 /*
  * 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;
 }
	/*
	* 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;
	}