Merge branch 'linux-next' of git://git.infradead.org/ubifs-2.6
[linux-2.6] / kernel / itimer.c
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  */
26 static 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
44 int 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, &times);
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
103 SYSCALL_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  */
121 enum 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
137 int 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:
153 again:
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  */
238 unsigned 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
263 SYSCALL_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 }