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/smp_lock.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/syscalls.h>
  13 #include <linux/time.h>
  14 #include <linux/posix-timers.h>
  15 #include <linux/hrtimer.h>
  16
  17 #include <asm/uaccess.h>
  18
  19 /**
  20  * itimer_get_remtime - get remaining time for the timer
  21  *
  22  * @timer: the timer to read
  23  *
  24  * Returns the delta between the expiry time and now, which can be
  25  * less than zero or 1usec for an pending expired timer
  26  */
  27 static struct timeval itimer_get_remtime(struct hrtimer *timer)
  28 {
  29         ktime_t rem = hrtimer_get_remaining(timer);
  30
  31         /*
  32          * Racy but safe: if the itimer expires after the above
  33          * hrtimer_get_remtime() call but before this condition
  34          * then we return 0 - which is correct.
  35          */
  36         if (hrtimer_active(timer)) {
  37                 if (rem.tv64 <= 0)
  38                         rem.tv64 = NSEC_PER_USEC;
  39         } else
  40                 rem.tv64 = 0;
  41
  42         return ktime_to_timeval(rem);
  43 }
  44
  45 int do_getitimer(int which, struct itimerval *value)
  46 {
  47         struct task_struct *tsk = current;
  48         cputime_t cinterval, cval;
  49
  50         switch (which) {
  51         case ITIMER_REAL:
  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                 break;
  56         case ITIMER_VIRTUAL:
  57                 read_lock(&tasklist_lock);
  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_struct *t = tsk;
  63                         cputime_t utime = tsk->signal->utime;
  64                         do {
  65                                 utime = cputime_add(utime, t->utime);
  66                                 t = next_thread(t);
  67                         } while (t != tsk);
  68                         if (cputime_le(cval, utime)) { /* about to fire */
  69                                 cval = jiffies_to_cputime(1);
  70                         } else {
  71                                 cval = cputime_sub(cval, utime);
  72                         }
  73                 }
  74                 spin_unlock_irq(&tsk->sighand->siglock);
  75                 read_unlock(&tasklist_lock);
  76                 cputime_to_timeval(cval, &value->it_value);
  77                 cputime_to_timeval(cinterval, &value->it_interval);
  78                 break;
  79         case ITIMER_PROF:
  80                 read_lock(&tasklist_lock);
  81                 spin_lock_irq(&tsk->sighand->siglock);
  82                 cval = tsk->signal->it_prof_expires;
  83                 cinterval = tsk->signal->it_prof_incr;
  84                 if (!cputime_eq(cval, cputime_zero)) {
  85                         struct task_struct *t = tsk;
  86                         cputime_t ptime = cputime_add(tsk->signal->utime,
  87                                                       tsk->signal->stime);
  88                         do {
  89                                 ptime = cputime_add(ptime,
  90                                                     cputime_add(t->utime,
  91                                                                 t->stime));
  92                                 t = next_thread(t);
  93                         } while (t != tsk);
  94                         if (cputime_le(cval, ptime)) { /* about to fire */
  95                                 cval = jiffies_to_cputime(1);
  96                         } else {
  97                                 cval = cputime_sub(cval, ptime);
  98                         }
  99                 }
 100                 spin_unlock_irq(&tsk->sighand->siglock);
 101                 read_unlock(&tasklist_lock);
 102                 cputime_to_timeval(cval, &value->it_value);
 103                 cputime_to_timeval(cinterval, &value->it_interval);
 104                 break;
 105         default:
 106                 return(-EINVAL);
 107         }
 108         return 0;
 109 }
 110
 111 asmlinkage long sys_getitimer(int which, struct itimerval __user *value)
 112 {
 113         int error = -EFAULT;
 114         struct itimerval get_buffer;
 115
 116         if (value) {
 117                 error = do_getitimer(which, &get_buffer);
 118                 if (!error &&
 119                     copy_to_user(value, &get_buffer, sizeof(get_buffer)))
 120                         error = -EFAULT;
 121         }
 122         return error;
 123 }
 124
 125
 126 /*
 127  * The timer is automagically restarted, when interval != 0
 128  */
 129 int it_real_fn(void *data)
 130 {
 131         struct task_struct *tsk = (struct task_struct *) data;
 132
 133         send_group_sig_info(SIGALRM, SEND_SIG_PRIV, tsk);
 134
 135         if (tsk->signal->it_real_incr.tv64 != 0) {
 136                 hrtimer_forward(&tsk->signal->real_timer,
 137                                tsk->signal->it_real_incr);
 138
 139                 return HRTIMER_RESTART;
 140         }
 141         return HRTIMER_NORESTART;
 142 }
 143
 144 int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
 145 {
 146         struct task_struct *tsk = current;
 147         struct hrtimer *timer;
 148         ktime_t expires;
 149         cputime_t cval, cinterval, nval, ninterval;
 150
 151         switch (which) {
 152         case ITIMER_REAL:
 153                 timer = &tsk->signal->real_timer;
 154                 hrtimer_cancel(timer);
 155                 if (ovalue) {
 156                         ovalue->it_value = itimer_get_remtime(timer);
 157                         ovalue->it_interval
 158                                 = ktime_to_timeval(tsk->signal->it_real_incr);
 159                 }
 160                 tsk->signal->it_real_incr =
 161                         timeval_to_ktime(value->it_interval);
 162                 expires = timeval_to_ktime(value->it_value);
 163                 if (expires.tv64 != 0)
 164                         hrtimer_start(timer, expires, HRTIMER_REL);
 165                 break;
 166         case ITIMER_VIRTUAL:
 167                 nval = timeval_to_cputime(&value->it_value);
 168                 ninterval = timeval_to_cputime(&value->it_interval);
 169                 read_lock(&tasklist_lock);
 170                 spin_lock_irq(&tsk->sighand->siglock);
 171                 cval = tsk->signal->it_virt_expires;
 172                 cinterval = tsk->signal->it_virt_incr;
 173                 if (!cputime_eq(cval, cputime_zero) ||
 174                     !cputime_eq(nval, cputime_zero)) {
 175                         if (cputime_gt(nval, cputime_zero))
 176                                 nval = cputime_add(nval,
 177                                                    jiffies_to_cputime(1));
 178                         set_process_cpu_timer(tsk, CPUCLOCK_VIRT,
 179                                               &nval, &cval);
 180                 }
 181                 tsk->signal->it_virt_expires = nval;
 182                 tsk->signal->it_virt_incr = ninterval;
 183                 spin_unlock_irq(&tsk->sighand->siglock);
 184                 read_unlock(&tasklist_lock);
 185                 if (ovalue) {
 186                         cputime_to_timeval(cval, &ovalue->it_value);
 187                         cputime_to_timeval(cinterval, &ovalue->it_interval);
 188                 }
 189                 break;
 190         case ITIMER_PROF:
 191                 nval = timeval_to_cputime(&value->it_value);
 192                 ninterval = timeval_to_cputime(&value->it_interval);
 193                 read_lock(&tasklist_lock);
 194                 spin_lock_irq(&tsk->sighand->siglock);
 195                 cval = tsk->signal->it_prof_expires;
 196                 cinterval = tsk->signal->it_prof_incr;
 197                 if (!cputime_eq(cval, cputime_zero) ||
 198                     !cputime_eq(nval, cputime_zero)) {
 199                         if (cputime_gt(nval, cputime_zero))
 200                                 nval = cputime_add(nval,
 201                                                    jiffies_to_cputime(1));
 202                         set_process_cpu_timer(tsk, CPUCLOCK_PROF,
 203                                               &nval, &cval);
 204                 }
 205                 tsk->signal->it_prof_expires = nval;
 206                 tsk->signal->it_prof_incr = ninterval;
 207                 spin_unlock_irq(&tsk->sighand->siglock);
 208                 read_unlock(&tasklist_lock);
 209                 if (ovalue) {
 210                         cputime_to_timeval(cval, &ovalue->it_value);
 211                         cputime_to_timeval(cinterval, &ovalue->it_interval);
 212                 }
 213                 break;
 214         default:
 215                 return -EINVAL;
 216         }
 217         return 0;
 218 }
 219
 220 asmlinkage long sys_setitimer(int which,
 221                               struct itimerval __user *value,
 222                               struct itimerval __user *ovalue)
 223 {
 224         struct itimerval set_buffer, get_buffer;
 225         int error;
 226
 227         if (value) {
 228                 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
 229                         return -EFAULT;
 230         } else
 231                 memset((char *) &set_buffer, 0, sizeof(set_buffer));
 232
 233         error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
 234         if (error || !ovalue)
 235                 return error;
 236
 237         if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
 238                 return -EFAULT;
 239         return 0;
 240 }