2 * linux/kernel/itimer.c
4 * Copyright (C) 1992 Darren Senn
7 /* These are all the functions necessary to implement itimers */
10 #include <linux/smp_lock.h>
11 #include <linux/interrupt.h>
13 #include <asm/uaccess.h>
16 * change timeval to jiffies, trying to avoid the
17 * most obvious overflows..
19 * The tv_*sec values are signed, but nothing seems to
20 * indicate whether we really should use them as signed values
21 * when doing itimers. POSIX doesn't mention this (but if
22 * alarm() uses itimers without checking, we have to use unsigned
25 static unsigned long tvtojiffies(struct timeval *value)
27 unsigned long sec = (unsigned) value->tv_sec;
28 unsigned long usec = (unsigned) value->tv_usec;
30 if (sec > (ULONG_MAX / HZ))
32 usec += 1000000 / HZ - 1;
37 static void jiffiestotv(unsigned long jiffies, struct timeval *value)
39 value->tv_usec = (jiffies % HZ) * (1000000 / HZ);
40 value->tv_sec = jiffies / HZ;
43 int do_getitimer(int which, struct itimerval *value)
45 register unsigned long val, interval;
49 interval = current->it_real_incr;
52 * FIXME! This needs to be atomic, in case the kernel timer happens!
54 if (timer_pending(¤t->real_timer)) {
55 val = current->real_timer.expires - jiffies;
57 /* look out for negative/zero itimer.. */
63 val = current->it_virt_value;
64 interval = current->it_virt_incr;
67 val = current->it_prof_value;
68 interval = current->it_prof_incr;
73 jiffiestotv(val, &value->it_value);
74 jiffiestotv(interval, &value->it_interval);
78 /* SMP: Only we modify our itimer values. */
79 asmlinkage long sys_getitimer(int which, struct itimerval *value)
82 struct itimerval get_buffer;
85 error = do_getitimer(which, &get_buffer);
87 copy_to_user(value, &get_buffer, sizeof(get_buffer)))
93 void it_real_fn(unsigned long __data)
95 struct task_struct * p = (struct task_struct *) __data;
96 unsigned long interval;
98 send_sig(SIGALRM, p, 1);
99 interval = p->it_real_incr;
101 if (interval > (unsigned long) LONG_MAX)
103 p->real_timer.expires = jiffies + interval;
104 add_timer(&p->real_timer);
108 int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
110 register unsigned long i, j;
113 i = tvtojiffies(&value->it_interval);
114 j = tvtojiffies(&value->it_value);
115 if (ovalue && (k = do_getitimer(which, ovalue)) < 0)
119 del_timer_sync(¤t->real_timer);
120 current->it_real_value = j;
121 current->it_real_incr = i;
124 if (j > (unsigned long) LONG_MAX)
127 current->real_timer.expires = i;
128 add_timer(¤t->real_timer);
133 current->it_virt_value = j;
134 current->it_virt_incr = i;
139 current->it_prof_value = j;
140 current->it_prof_incr = i;
148 /* SMP: Again, only we play with our itimers, and signals are SMP safe
149 * now so that is not an issue at all anymore.
151 asmlinkage long sys_setitimer(int which, struct itimerval *value,
152 struct itimerval *ovalue)
154 struct itimerval set_buffer, get_buffer;
158 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
161 memset((char *) &set_buffer, 0, sizeof(set_buffer));
163 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : 0);
164 if (error || !ovalue)
167 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))