Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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kernel
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linux
1/*
2 * linux/kernel/itimer.c
3 *
4 * Copyright (C) 1992 Darren Senn
5 */
6
7/* These are all the functions necessary to implement itimers */
8
9#include <linux/mm.h>
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>
15
16#include <asm/uaccess.h>
17
18/**
19 * itimer_get_remtime - get remaining time for the timer
20 *
21 * @timer: the timer to read
22 *
23 * Returns the delta between the expiry time and now, which can be
24 * less than zero or 1usec for an pending expired timer
25 */
26static struct timeval itimer_get_remtime(struct hrtimer *timer)
27{
28 ktime_t rem = hrtimer_get_remaining(timer);
29
30 /*
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.
34 */
35 if (hrtimer_active(timer)) {
36 if (rem.tv64 <= 0)
37 rem.tv64 = NSEC_PER_USEC;
38 } else
39 rem.tv64 = 0;
40
41 return ktime_to_timeval(rem);
42}
43
44int do_getitimer(int which, struct itimerval *value)
45{
46 struct task_struct *tsk = current;
47 cputime_t cinterval, cval;
48
49 switch (which) {
50 case ITIMER_REAL:
51 spin_lock_irq(&tsk->sighand->siglock);
52 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
53 value->it_interval =
54 ktime_to_timeval(tsk->signal->it_real_incr);
55 spin_unlock_irq(&tsk->sighand->siglock);
56 break;
57 case ITIMER_VIRTUAL:
58 spin_lock_irq(&tsk->sighand->siglock);
59 cval = tsk->signal->it_virt_expires;
60 cinterval = tsk->signal->it_virt_incr;
61 if (!cputime_eq(cval, cputime_zero)) {
62 struct task_cputime cputime;
63 cputime_t utime;
64
65 thread_group_cputimer(tsk, &cputime);
66 utime = cputime.utime;
67 if (cputime_le(cval, utime)) { /* about to fire */
68 cval = jiffies_to_cputime(1);
69 } else {
70 cval = cputime_sub(cval, utime);
71 }
72 }
73 spin_unlock_irq(&tsk->sighand->siglock);
74 cputime_to_timeval(cval, &value->it_value);
75 cputime_to_timeval(cinterval, &value->it_interval);
76 break;
77 case ITIMER_PROF:
78 spin_lock_irq(&tsk->sighand->siglock);
79 cval = tsk->signal->it_prof_expires;
80 cinterval = tsk->signal->it_prof_incr;
81 if (!cputime_eq(cval, cputime_zero)) {
82 struct task_cputime times;
83 cputime_t ptime;
84
85 thread_group_cputimer(tsk, ×);
86 ptime = cputime_add(times.utime, times.stime);
87 if (cputime_le(cval, ptime)) { /* about to fire */
88 cval = jiffies_to_cputime(1);
89 } else {
90 cval = cputime_sub(cval, ptime);
91 }
92 }
93 spin_unlock_irq(&tsk->sighand->siglock);
94 cputime_to_timeval(cval, &value->it_value);
95 cputime_to_timeval(cinterval, &value->it_interval);
96 break;
97 default:
98 return(-EINVAL);
99 }
100 return 0;
101}
102
103SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
104{
105 int error = -EFAULT;
106 struct itimerval get_buffer;
107
108 if (value) {
109 error = do_getitimer(which, &get_buffer);
110 if (!error &&
111 copy_to_user(value, &get_buffer, sizeof(get_buffer)))
112 error = -EFAULT;
113 }
114 return error;
115}
116
117
118/*
119 * The timer is automagically restarted, when interval != 0
120 */
121enum hrtimer_restart it_real_fn(struct hrtimer *timer)
122{
123 struct signal_struct *sig =
124 container_of(timer, struct signal_struct, real_timer);
125
126 kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
127
128 return HRTIMER_NORESTART;
129}
130
131/*
132 * Returns true if the timeval is in canonical form
133 */
134#define timeval_valid(t) \
135 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
136
137int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
138{
139 struct task_struct *tsk = current;
140 struct hrtimer *timer;
141 ktime_t expires;
142 cputime_t cval, cinterval, nval, ninterval;
143
144 /*
145 * Validate the timevals in value.
146 */
147 if (!timeval_valid(&value->it_value) ||
148 !timeval_valid(&value->it_interval))
149 return -EINVAL;
150
151 switch (which) {
152 case ITIMER_REAL:
153again:
154 spin_lock_irq(&tsk->sighand->siglock);
155 timer = &tsk->signal->real_timer;
156 if (ovalue) {
157 ovalue->it_value = itimer_get_remtime(timer);
158 ovalue->it_interval
159 = ktime_to_timeval(tsk->signal->it_real_incr);
160 }
161 /* We are sharing ->siglock with it_real_fn() */
162 if (hrtimer_try_to_cancel(timer) < 0) {
163 spin_unlock_irq(&tsk->sighand->siglock);
164 goto again;
165 }
166 expires = timeval_to_ktime(value->it_value);
167 if (expires.tv64 != 0) {
168 tsk->signal->it_real_incr =
169 timeval_to_ktime(value->it_interval);
170 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
171 } else
172 tsk->signal->it_real_incr.tv64 = 0;
173
174 spin_unlock_irq(&tsk->sighand->siglock);
175 break;
176 case ITIMER_VIRTUAL:
177 nval = timeval_to_cputime(&value->it_value);
178 ninterval = timeval_to_cputime(&value->it_interval);
179 spin_lock_irq(&tsk->sighand->siglock);
180 cval = tsk->signal->it_virt_expires;
181 cinterval = tsk->signal->it_virt_incr;
182 if (!cputime_eq(cval, cputime_zero) ||
183 !cputime_eq(nval, cputime_zero)) {
184 if (cputime_gt(nval, cputime_zero))
185 nval = cputime_add(nval,
186 jiffies_to_cputime(1));
187 set_process_cpu_timer(tsk, CPUCLOCK_VIRT,
188 &nval, &cval);
189 }
190 tsk->signal->it_virt_expires = nval;
191 tsk->signal->it_virt_incr = ninterval;
192 spin_unlock_irq(&tsk->sighand->siglock);
193 if (ovalue) {
194 cputime_to_timeval(cval, &ovalue->it_value);
195 cputime_to_timeval(cinterval, &ovalue->it_interval);
196 }
197 break;
198 case ITIMER_PROF:
199 nval = timeval_to_cputime(&value->it_value);
200 ninterval = timeval_to_cputime(&value->it_interval);
201 spin_lock_irq(&tsk->sighand->siglock);
202 cval = tsk->signal->it_prof_expires;
203 cinterval = tsk->signal->it_prof_incr;
204 if (!cputime_eq(cval, cputime_zero) ||
205 !cputime_eq(nval, cputime_zero)) {
206 if (cputime_gt(nval, cputime_zero))
207 nval = cputime_add(nval,
208 jiffies_to_cputime(1));
209 set_process_cpu_timer(tsk, CPUCLOCK_PROF,
210 &nval, &cval);
211 }
212 tsk->signal->it_prof_expires = nval;
213 tsk->signal->it_prof_incr = ninterval;
214 spin_unlock_irq(&tsk->sighand->siglock);
215 if (ovalue) {
216 cputime_to_timeval(cval, &ovalue->it_value);
217 cputime_to_timeval(cinterval, &ovalue->it_interval);
218 }
219 break;
220 default:
221 return -EINVAL;
222 }
223 return 0;
224}
225
226/**
227 * alarm_setitimer - set alarm in seconds
228 *
229 * @seconds: number of seconds until alarm
230 * 0 disables the alarm
231 *
232 * Returns the remaining time in seconds of a pending timer or 0 when
233 * the timer is not active.
234 *
235 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
236 * negative timeval settings which would cause immediate expiry.
237 */
238unsigned int alarm_setitimer(unsigned int seconds)
239{
240 struct itimerval it_new, it_old;
241
242#if BITS_PER_LONG < 64
243 if (seconds > INT_MAX)
244 seconds = INT_MAX;
245#endif
246 it_new.it_value.tv_sec = seconds;
247 it_new.it_value.tv_usec = 0;
248 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
249
250 do_setitimer(ITIMER_REAL, &it_new, &it_old);
251
252 /*
253 * We can't return 0 if we have an alarm pending ... And we'd
254 * better return too much than too little anyway
255 */
256 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
257 it_old.it_value.tv_usec >= 500000)
258 it_old.it_value.tv_sec++;
259
260 return it_old.it_value.tv_sec;
261}
262
263SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
264 struct itimerval __user *, ovalue)
265{
266 struct itimerval set_buffer, get_buffer;
267 int error;
268
269 if (value) {
270 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
271 return -EFAULT;
272 } else
273 memset((char *) &set_buffer, 0, sizeof(set_buffer));
274
275 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
276 if (error || !ovalue)
277 return error;
278
279 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
280 return -EFAULT;
281 return 0;
282}