2 * linux/kernel/itimer.c
4 * Copyright (C) 1992 Darren Senn
7 /* These are all the functions necessary to implement itimers */
10 #include <linux/interrupt.h>
11 #include <linux/syscalls.h>
12 #include <linux/time.h>
13 #include <linux/posix-timers.h>
14 #include <linux/hrtimer.h>
16 #include <asm/uaccess.h>
19 * itimer_get_remtime - get remaining time for the timer
21 * @timer: the timer to read
23 * Returns the delta between the expiry time and now, which can be
24 * less than zero or 1usec for an pending expired timer
26 static struct timeval itimer_get_remtime(struct hrtimer *timer)
28 ktime_t rem = hrtimer_get_remaining(timer);
31 * Racy but safe: if the itimer expires after the above
32 * hrtimer_get_remtime() call but before this condition
33 * then we return 0 - which is correct.
35 if (hrtimer_active(timer)) {
37 rem.tv64 = NSEC_PER_USEC;
41 return ktime_to_timeval(rem);
44 static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
45 struct itimerval *value)
47 cputime_t cval, cinterval;
48 struct cpu_itimer *it = &tsk->signal->it[clock_id];
50 spin_lock_irq(&tsk->sighand->siglock);
54 if (!cputime_eq(cval, cputime_zero)) {
55 struct task_cputime cputime;
58 thread_group_cputimer(tsk, &cputime);
59 if (clock_id == CPUCLOCK_PROF)
60 t = cputime_add(cputime.utime, cputime.stime);
65 if (cputime_le(cval, t))
67 cval = jiffies_to_cputime(1);
69 cval = cputime_sub(cval, t);
72 spin_unlock_irq(&tsk->sighand->siglock);
74 cputime_to_timeval(cval, &value->it_value);
75 cputime_to_timeval(cinterval, &value->it_interval);
78 int do_getitimer(int which, struct itimerval *value)
80 struct task_struct *tsk = current;
84 spin_lock_irq(&tsk->sighand->siglock);
85 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
87 ktime_to_timeval(tsk->signal->it_real_incr);
88 spin_unlock_irq(&tsk->sighand->siglock);
91 get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
94 get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
102 SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
105 struct itimerval get_buffer;
108 error = do_getitimer(which, &get_buffer);
110 copy_to_user(value, &get_buffer, sizeof(get_buffer)))
118 * The timer is automagically restarted, when interval != 0
120 enum hrtimer_restart it_real_fn(struct hrtimer *timer)
122 struct signal_struct *sig =
123 container_of(timer, struct signal_struct, real_timer);
125 kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
127 return HRTIMER_NORESTART;
130 static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
131 struct itimerval *value, struct itimerval *ovalue)
133 cputime_t cval, cinterval, nval, ninterval;
134 struct cpu_itimer *it = &tsk->signal->it[clock_id];
136 nval = timeval_to_cputime(&value->it_value);
137 ninterval = timeval_to_cputime(&value->it_interval);
139 spin_lock_irq(&tsk->sighand->siglock);
142 cinterval = it->incr;
143 if (!cputime_eq(cval, cputime_zero) ||
144 !cputime_eq(nval, cputime_zero)) {
145 if (cputime_gt(nval, cputime_zero))
146 nval = cputime_add(nval, jiffies_to_cputime(1));
147 set_process_cpu_timer(tsk, clock_id, &nval, &cval);
150 it->incr = ninterval;
152 spin_unlock_irq(&tsk->sighand->siglock);
155 cputime_to_timeval(cval, &ovalue->it_value);
156 cputime_to_timeval(cinterval, &ovalue->it_interval);
161 * Returns true if the timeval is in canonical form
163 #define timeval_valid(t) \
164 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
166 int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
168 struct task_struct *tsk = current;
169 struct hrtimer *timer;
173 * Validate the timevals in value.
175 if (!timeval_valid(&value->it_value) ||
176 !timeval_valid(&value->it_interval))
182 spin_lock_irq(&tsk->sighand->siglock);
183 timer = &tsk->signal->real_timer;
185 ovalue->it_value = itimer_get_remtime(timer);
187 = ktime_to_timeval(tsk->signal->it_real_incr);
189 /* We are sharing ->siglock with it_real_fn() */
190 if (hrtimer_try_to_cancel(timer) < 0) {
191 spin_unlock_irq(&tsk->sighand->siglock);
194 expires = timeval_to_ktime(value->it_value);
195 if (expires.tv64 != 0) {
196 tsk->signal->it_real_incr =
197 timeval_to_ktime(value->it_interval);
198 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
200 tsk->signal->it_real_incr.tv64 = 0;
202 spin_unlock_irq(&tsk->sighand->siglock);
205 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
208 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
217 * alarm_setitimer - set alarm in seconds
219 * @seconds: number of seconds until alarm
220 * 0 disables the alarm
222 * Returns the remaining time in seconds of a pending timer or 0 when
223 * the timer is not active.
225 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
226 * negative timeval settings which would cause immediate expiry.
228 unsigned int alarm_setitimer(unsigned int seconds)
230 struct itimerval it_new, it_old;
232 #if BITS_PER_LONG < 64
233 if (seconds > INT_MAX)
236 it_new.it_value.tv_sec = seconds;
237 it_new.it_value.tv_usec = 0;
238 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
240 do_setitimer(ITIMER_REAL, &it_new, &it_old);
243 * We can't return 0 if we have an alarm pending ... And we'd
244 * better return too much than too little anyway
246 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
247 it_old.it_value.tv_usec >= 500000)
248 it_old.it_value.tv_sec++;
250 return it_old.it_value.tv_sec;
253 SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
254 struct itimerval __user *, ovalue)
256 struct itimerval set_buffer, get_buffer;
260 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
263 memset((char *) &set_buffer, 0, sizeof(set_buffer));
265 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
266 if (error || !ovalue)
269 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))