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
  15 #include <asm/uaccess.h>
  16
  17 int do_getitimer(int which, struct itimerval *value)
  18 {
  19         register unsigned long val, interval;
  20
  21         switch (which) {
  22         case ITIMER_REAL:
  23                 interval = current->it_real_incr;
  24                 val = 0;
  25                 /*
  26                  * FIXME! This needs to be atomic, in case the kernel timer happens!
  27                  */
  28                 if (timer_pending(&current->real_timer)) {
  29                         val = current->real_timer.expires - jiffies;
  30
  31                         /* look out for negative/zero itimer.. */
  32                         if ((long) val <= 0)
  33                                 val = 1;
  34                 }
  35                 break;
  36         case ITIMER_VIRTUAL:
  37                 val = current->it_virt_value;
  38                 interval = current->it_virt_incr;
  39                 break;
  40         case ITIMER_PROF:
  41                 val = current->it_prof_value;
  42                 interval = current->it_prof_incr;
  43                 break;
  44         default:
  45                 return(-EINVAL);
  46         }
  47         jiffies_to_timeval(val, &value->it_value);
  48         jiffies_to_timeval(interval, &value->it_interval);
  49         return 0;
  50 }
  51
  52 /* SMP: Only we modify our itimer values. */
  53 asmlinkage long sys_getitimer(int which, struct itimerval __user *value)
  54 {
  55         int error = -EFAULT;
  56         struct itimerval get_buffer;
  57
  58         if (value) {
  59                 error = do_getitimer(which, &get_buffer);
  60                 if (!error &&
  61                     copy_to_user(value, &get_buffer, sizeof(get_buffer)))
  62                         error = -EFAULT;
  63         }
  64         return error;
  65 }
  66
  67 void it_real_fn(unsigned long __data)
  68 {
  69         struct task_struct * p = (struct task_struct *) __data;
  70         unsigned long interval;
  71
  72         send_group_sig_info(SIGALRM, SEND_SIG_PRIV, p);
  73         interval = p->it_real_incr;
  74         if (interval) {
  75                 if (interval > (unsigned long) LONG_MAX)
  76                         interval = LONG_MAX;
  77                 p->real_timer.expires = jiffies + interval;
  78                 add_timer(&p->real_timer);
  79         }
  80 }
  81
  82 int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
  83 {
  84         register unsigned long i, j;
  85         int k;
  86
  87         i = timeval_to_jiffies(&value->it_interval);
  88         j = timeval_to_jiffies(&value->it_value);
  89         if (ovalue && (k = do_getitimer(which, ovalue)) < 0)
  90                 return k;
  91         switch (which) {
  92                 case ITIMER_REAL:
  93                         del_timer_sync(&current->real_timer);
  94                         current->it_real_value = j;
  95                         current->it_real_incr = i;
  96                         if (!j)
  97                                 break;
  98                         if (j > (unsigned long) LONG_MAX)
  99                                 j = LONG_MAX;
 100                         i = j + jiffies;
 101                         current->real_timer.expires = i;
 102                         add_timer(&current->real_timer);
 103                         break;
 104                 case ITIMER_VIRTUAL:
 105                         if (j)
 106                                 j++;
 107                         current->it_virt_value = j;
 108                         current->it_virt_incr = i;
 109                         break;
 110                 case ITIMER_PROF:
 111                         if (j)
 112                                 j++;
 113                         current->it_prof_value = j;
 114                         current->it_prof_incr = i;
 115                         break;
 116                 default:
 117                         return -EINVAL;
 118         }
 119         return 0;
 120 }
 121
 122 /* SMP: Again, only we play with our itimers, and signals are SMP safe
 123  *      now so that is not an issue at all anymore.
 124  */
 125 asmlinkage long sys_setitimer(int which,
 126                               struct itimerval __user *value,
 127                               struct itimerval __user *ovalue)
 128 {
 129         struct itimerval set_buffer, get_buffer;
 130         int error;
 131
 132         if (value) {
 133                 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
 134                         return -EFAULT;
 135         } else
 136                 memset((char *) &set_buffer, 0, sizeof(set_buffer));
 137
 138         error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
 139         if (error || !ovalue)
 140                 return error;
 141
 142         if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
 143                 return -EFAULT;
 144         return 0;
 145 }