/* * 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;}