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 *const 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 = cputime_one_jiffy;
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 inline u32 cputime_sub_ns(cputime_t ct, s64 real_ns)
135 cputime_to_timespec(ct, &ts);
136 cpu_ns = timespec_to_ns(&ts);
138 return (cpu_ns <= real_ns) ? 0 : cpu_ns - real_ns;
141 static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
142 const struct itimerval *const value,
143 struct itimerval *const ovalue)
145 cputime_t cval, nval, cinterval, ninterval;
146 s64 ns_ninterval, ns_nval;
147 struct cpu_itimer *it = &tsk->signal->it[clock_id];
149 nval = timeval_to_cputime(&value->it_value);
150 ns_nval = timeval_to_ns(&value->it_value);
151 ninterval = timeval_to_cputime(&value->it_interval);
152 ns_ninterval = timeval_to_ns(&value->it_interval);
154 it->incr_error = cputime_sub_ns(ninterval, ns_ninterval);
155 it->error = cputime_sub_ns(nval, ns_nval);
157 spin_lock_irq(&tsk->sighand->siglock);
160 cinterval = it->incr;
161 if (!cputime_eq(cval, cputime_zero) ||
162 !cputime_eq(nval, cputime_zero)) {
163 if (cputime_gt(nval, cputime_zero))
164 nval = cputime_add(nval, cputime_one_jiffy);
165 set_process_cpu_timer(tsk, clock_id, &nval, &cval);
168 it->incr = ninterval;
170 spin_unlock_irq(&tsk->sighand->siglock);
173 cputime_to_timeval(cval, &ovalue->it_value);
174 cputime_to_timeval(cinterval, &ovalue->it_interval);
179 * Returns true if the timeval is in canonical form
181 #define timeval_valid(t) \
182 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
184 int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
186 struct task_struct *tsk = current;
187 struct hrtimer *timer;
191 * Validate the timevals in value.
193 if (!timeval_valid(&value->it_value) ||
194 !timeval_valid(&value->it_interval))
200 spin_lock_irq(&tsk->sighand->siglock);
201 timer = &tsk->signal->real_timer;
203 ovalue->it_value = itimer_get_remtime(timer);
205 = ktime_to_timeval(tsk->signal->it_real_incr);
207 /* We are sharing ->siglock with it_real_fn() */
208 if (hrtimer_try_to_cancel(timer) < 0) {
209 spin_unlock_irq(&tsk->sighand->siglock);
212 expires = timeval_to_ktime(value->it_value);
213 if (expires.tv64 != 0) {
214 tsk->signal->it_real_incr =
215 timeval_to_ktime(value->it_interval);
216 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
218 tsk->signal->it_real_incr.tv64 = 0;
220 spin_unlock_irq(&tsk->sighand->siglock);
223 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
226 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
235 * alarm_setitimer - set alarm in seconds
237 * @seconds: number of seconds until alarm
238 * 0 disables the alarm
240 * Returns the remaining time in seconds of a pending timer or 0 when
241 * the timer is not active.
243 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
244 * negative timeval settings which would cause immediate expiry.
246 unsigned int alarm_setitimer(unsigned int seconds)
248 struct itimerval it_new, it_old;
250 #if BITS_PER_LONG < 64
251 if (seconds > INT_MAX)
254 it_new.it_value.tv_sec = seconds;
255 it_new.it_value.tv_usec = 0;
256 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
258 do_setitimer(ITIMER_REAL, &it_new, &it_old);
261 * We can't return 0 if we have an alarm pending ... And we'd
262 * better return too much than too little anyway
264 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
265 it_old.it_value.tv_usec >= 500000)
266 it_old.it_value.tv_sec++;
268 return it_old.it_value.tv_sec;
271 SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
272 struct itimerval __user *, ovalue)
274 struct itimerval set_buffer, get_buffer;
278 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
281 memset((char *) &set_buffer, 0, sizeof(set_buffer));
283 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
284 if (error || !ovalue)
287 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))