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
  16 #include <asm/uaccess.h>
  17
  18 static unsigned long it_real_value(struct signal_struct *sig)
  19 {
  20         unsigned long val = 0;
  21         if (timer_pending(&sig->real_timer)) {
  22                 val = sig->real_timer.expires - jiffies;
  23
  24                 /* look out for negative/zero itimer.. */
  25                 if ((long) val <= 0)
  26                         val = 1;
  27         }
  28         return val;
  29 }
  30
  31 int do_getitimer(int which, struct itimerval *value)
  32 {
  33         struct task_struct *tsk = current;
  34         unsigned long interval, val;
  35         cputime_t cinterval, cval;
  36
  37         switch (which) {
  38         case ITIMER_REAL:
  39                 spin_lock_irq(&tsk->sighand->siglock);
  40                 interval = tsk->signal->it_real_incr;
  41                 val = it_real_value(tsk->signal);
  42                 spin_unlock_irq(&tsk->sighand->siglock);
  43                 jiffies_to_timeval(val, &value->it_value);
  44                 jiffies_to_timeval(interval, &value->it_interval);
  45                 break;
  46         case ITIMER_VIRTUAL:
  47                 read_lock(&tasklist_lock);
  48                 spin_lock_irq(&tsk->sighand->siglock);
  49                 cval = tsk->signal->it_virt_expires;
  50                 cinterval = tsk->signal->it_virt_incr;
  51                 if (!cputime_eq(cval, cputime_zero)) {
  52                         struct task_struct *t = tsk;
  53                         cputime_t utime = tsk->signal->utime;
  54                         do {
  55                                 utime = cputime_add(utime, t->utime);
  56                                 t = next_thread(t);
  57                         } while (t != tsk);
  58                         if (cputime_le(cval, utime)) { /* about to fire */
  59                                 cval = jiffies_to_cputime(1);
  60                         } else {
  61                                 cval = cputime_sub(cval, utime);
  62                         }
  63                 }
  64                 spin_unlock_irq(&tsk->sighand->siglock);
  65                 read_unlock(&tasklist_lock);
  66                 cputime_to_timeval(cval, &value->it_value);
  67                 cputime_to_timeval(cinterval, &value->it_interval);
  68                 break;
  69         case ITIMER_PROF:
  70                 read_lock(&tasklist_lock);
  71                 spin_lock_irq(&tsk->sighand->siglock);
  72                 cval = tsk->signal->it_prof_expires;
  73                 cinterval = tsk->signal->it_prof_incr;
  74                 if (!cputime_eq(cval, cputime_zero)) {
  75                         struct task_struct *t = tsk;
  76                         cputime_t ptime = cputime_add(tsk->signal->utime,
  77                                                       tsk->signal->stime);
  78                         do {
  79                                 ptime = cputime_add(ptime,
  80                                                     cputime_add(t->utime,
  81                                                                 t->stime));
  82                                 t = next_thread(t);
  83                         } while (t != tsk);
  84                         if (cputime_le(cval, ptime)) { /* about to fire */
  85                                 cval = jiffies_to_cputime(1);
  86                         } else {
  87                                 cval = cputime_sub(cval, ptime);
  88                         }
  89                 }
  90                 spin_unlock_irq(&tsk->sighand->siglock);
  91                 read_unlock(&tasklist_lock);
  92                 cputime_to_timeval(cval, &value->it_value);
  93                 cputime_to_timeval(cinterval, &value->it_interval);
  94                 break;
  95         default:
  96                 return(-EINVAL);
  97         }
  98         return 0;
  99 }
 100
 101 asmlinkage long sys_getitimer(int which, struct itimerval __user *value)
 102 {
 103         int error = -EFAULT;
 104         struct itimerval get_buffer;
 105
 106         if (value) {
 107                 error = do_getitimer(which, &get_buffer);
 108                 if (!error &&
 109                     copy_to_user(value, &get_buffer, sizeof(get_buffer)))
 110                         error = -EFAULT;
 111         }
 112         return error;
 113 }
 114
 115
 116 void it_real_fn(unsigned long __data)
 117 {
 118         struct task_struct * p = (struct task_struct *) __data;
 119         unsigned long inc = p->signal->it_real_incr;
 120
 121         send_group_sig_info(SIGALRM, SEND_SIG_PRIV, p);
 122
 123         /*
 124          * Now restart the timer if necessary.  We don't need any locking
 125          * here because do_setitimer makes sure we have finished running
 126          * before it touches anything.
 127          * Note, we KNOW we are (or should be) at a jiffie edge here so
 128          * we don't need the +1 stuff.  Also, we want to use the prior
 129          * expire value so as to not "slip" a jiffie if we are late.
 130          * Deal with requesting a time prior to "now" here rather than
 131          * in add_timer.
 132          */
 133         if (!inc)
 134                 return;
 135         while (time_before_eq(p->signal->real_timer.expires, jiffies))
 136                 p->signal->real_timer.expires += inc;
 137         add_timer(&p->signal->real_timer);
 138 }
 139
 140 int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
 141 {
 142         struct task_struct *tsk = current;
 143         unsigned long val, interval, expires;
 144         cputime_t cval, cinterval, nval, ninterval;
 145
 146         switch (which) {
 147         case ITIMER_REAL:
 148 again:
 149                 spin_lock_irq(&tsk->sighand->siglock);
 150                 interval = tsk->signal->it_real_incr;
 151                 val = it_real_value(tsk->signal);
 152                 /* We are sharing ->siglock with it_real_fn() */
 153                 if (try_to_del_timer_sync(&tsk->signal->real_timer) < 0) {
 154                         spin_unlock_irq(&tsk->sighand->siglock);
 155                         goto again;
 156                 }
 157                 tsk->signal->it_real_incr =
 158                         timeval_to_jiffies(&value->it_interval);
 159                 expires = timeval_to_jiffies(&value->it_value);
 160                 if (expires)
 161                         mod_timer(&tsk->signal->real_timer,
 162                                   jiffies + 1 + expires);
 163                 spin_unlock_irq(&tsk->sighand->siglock);
 164                 if (ovalue) {
 165                         jiffies_to_timeval(val, &ovalue->it_value);
 166                         jiffies_to_timeval(interval,
 167                                            &ovalue->it_interval);
 168                 }
 169                 break;
 170         case ITIMER_VIRTUAL:
 171                 nval = timeval_to_cputime(&value->it_value);
 172                 ninterval = timeval_to_cputime(&value->it_interval);
 173                 read_lock(&tasklist_lock);
 174                 spin_lock_irq(&tsk->sighand->siglock);
 175                 cval = tsk->signal->it_virt_expires;
 176                 cinterval = tsk->signal->it_virt_incr;
 177                 if (!cputime_eq(cval, cputime_zero) ||
 178                     !cputime_eq(nval, cputime_zero)) {
 179                         if (cputime_gt(nval, cputime_zero))
 180                                 nval = cputime_add(nval,
 181                                                    jiffies_to_cputime(1));
 182                         set_process_cpu_timer(tsk, CPUCLOCK_VIRT,
 183                                               &nval, &cval);
 184                 }
 185                 tsk->signal->it_virt_expires = nval;
 186                 tsk->signal->it_virt_incr = ninterval;
 187                 spin_unlock_irq(&tsk->sighand->siglock);
 188                 read_unlock(&tasklist_lock);
 189                 if (ovalue) {
 190                         cputime_to_timeval(cval, &ovalue->it_value);
 191                         cputime_to_timeval(cinterval, &ovalue->it_interval);
 192                 }
 193                 break;
 194         case ITIMER_PROF:
 195                 nval = timeval_to_cputime(&value->it_value);
 196                 ninterval = timeval_to_cputime(&value->it_interval);
 197                 read_lock(&tasklist_lock);
 198                 spin_lock_irq(&tsk->sighand->siglock);
 199                 cval = tsk->signal->it_prof_expires;
 200                 cinterval = tsk->signal->it_prof_incr;
 201                 if (!cputime_eq(cval, cputime_zero) ||
 202                     !cputime_eq(nval, cputime_zero)) {
 203                         if (cputime_gt(nval, cputime_zero))
 204                                 nval = cputime_add(nval,
 205                                                    jiffies_to_cputime(1));
 206                         set_process_cpu_timer(tsk, CPUCLOCK_PROF,
 207                                               &nval, &cval);
 208                 }
 209                 tsk->signal->it_prof_expires = nval;
 210                 tsk->signal->it_prof_incr = ninterval;
 211                 spin_unlock_irq(&tsk->sighand->siglock);
 212                 read_unlock(&tasklist_lock);
 213                 if (ovalue) {
 214                         cputime_to_timeval(cval, &ovalue->it_value);
 215                         cputime_to_timeval(cinterval, &ovalue->it_interval);
 216                 }
 217                 break;
 218         default:
 219                 return -EINVAL;
 220         }
 221         return 0;
 222 }
 223
 224 asmlinkage long sys_setitimer(int which,
 225                               struct itimerval __user *value,
 226                               struct itimerval __user *ovalue)
 227 {
 228         struct itimerval set_buffer, get_buffer;
 229         int error;
 230
 231         if (value) {
 232                 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
 233                         return -EFAULT;
 234         } else
 235                 memset((char *) &set_buffer, 0, sizeof(set_buffer));
 236
 237         error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
 238         if (error || !ovalue)
 239                 return error;
 240
 241         if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
 242                 return -EFAULT;
 243         return 0;
 244 }