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/time.h>
  13
  14 #include <asm/uaccess.h>
  15
  16 int do_getitimer(int which, struct itimerval *value)
  17 {
  18         register unsigned long val, interval;
  19
  20         switch (which) {
  21         case ITIMER_REAL:
  22                 interval = current->it_real_incr;
  23                 val = 0;
  24                 /*
  25                  * FIXME! This needs to be atomic, in case the kernel timer happens!
  26                  */
  27                 if (timer_pending(&current->real_timer)) {
  28                         val = current->real_timer.expires - jiffies;
  29
  30                         /* look out for negative/zero itimer.. */
  31                         if ((long) val <= 0)
  32                                 val = 1;
  33                 }
  34                 break;
  35         case ITIMER_VIRTUAL:
  36                 val = current->it_virt_value;
  37                 interval = current->it_virt_incr;
  38                 break;
  39         case ITIMER_PROF:
  40                 val = current->it_prof_value;
  41                 interval = current->it_prof_incr;
  42                 break;
  43         default:
  44                 return(-EINVAL);
  45         }
  46         jiffies_to_timeval(val, &value->it_value);
  47         jiffies_to_timeval(interval, &value->it_interval);
  48         return 0;
  49 }
  50
  51 /* SMP: Only we modify our itimer values. */
  52 asmlinkage long sys_getitimer(int which, struct itimerval __user *value)
  53 {
  54         int error = -EFAULT;
  55         struct itimerval get_buffer;
  56
  57         if (value) {
  58                 error = do_getitimer(which, &get_buffer);
  59                 if (!error &&
  60                     copy_to_user(value, &get_buffer, sizeof(get_buffer)))
  61                         error = -EFAULT;
  62         }
  63         return error;
  64 }
  65
  66 void it_real_fn(unsigned long __data)
  67 {
  68         struct task_struct * p = (struct task_struct *) __data;
  69         unsigned long interval;
  70
  71         send_group_sig_info(SIGALRM, SEND_SIG_PRIV, p);
  72         interval = p->it_real_incr;
  73         if (interval) {
  74                 if (interval > (unsigned long) LONG_MAX)
  75                         interval = LONG_MAX;
  76                 p->real_timer.expires = jiffies + interval;
  77                 add_timer(&p->real_timer);
  78         }
  79 }
  80
  81 int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
  82 {
  83         register unsigned long i, j;
  84         int k;
  85
  86         i = timeval_to_jiffies(&value->it_interval);
  87         j = timeval_to_jiffies(&value->it_value);
  88         if (ovalue && (k = do_getitimer(which, ovalue)) < 0)
  89                 return k;
  90         switch (which) {
  91                 case ITIMER_REAL:
  92                         del_timer_sync(&current->real_timer);
  93                         current->it_real_value = j;
  94                         current->it_real_incr = i;
  95                         if (!j)
  96                                 break;
  97                         if (j > (unsigned long) LONG_MAX)
  98                                 j = LONG_MAX;
  99                         i = j + jiffies;
 100                         current->real_timer.expires = i;
 101                         add_timer(&current->real_timer);
 102                         break;
 103                 case ITIMER_VIRTUAL:
 104                         if (j)
 105                                 j++;
 106                         current->it_virt_value = j;
 107                         current->it_virt_incr = i;
 108                         break;
 109                 case ITIMER_PROF:
 110                         if (j)
 111                                 j++;
 112                         current->it_prof_value = j;
 113                         current->it_prof_incr = i;
 114                         break;
 115                 default:
 116                         return -EINVAL;
 117         }
 118         return 0;
 119 }
 120
 121 /* SMP: Again, only we play with our itimers, and signals are SMP safe
 122  *      now so that is not an issue at all anymore.
 123  */
 124 asmlinkage long sys_setitimer(int which,
 125                               struct itimerval __user *value,
 126                               struct itimerval __user *ovalue)
 127 {
 128         struct itimerval set_buffer, get_buffer;
 129         int error;
 130
 131         if (value) {
 132                 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
 133                         return -EFAULT;
 134         } else
 135                 memset((char *) &set_buffer, 0, sizeof(set_buffer));
 136
 137         error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : 0);
 138         if (error || !ovalue)
 139                 return error;
 140
 141         if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
 142                 return -EFAULT;
 143         return 0;
 144 }