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
)))
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