| 1 | |
| 2 | * linux/kernel/itimer.c
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| 3 | *
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| 4 | * Copyright (C) 1992 Darren Senn
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| 5 |
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| 6 |
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| 7 |
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| 8 |
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| 9 | #include <linux/mm.h>
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| 10 | #include <linux/smp_lock.h>
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| 11 | #include <linux/interrupt.h>
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| 12 | #include <linux/syscalls.h>
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| 13 | #include <linux/time.h>
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| 14 | #include <linux/posix-timers.h>
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| 15 | #include <linux/hrtimer.h>
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| 16 |
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| 17 | #include <asm/uaccess.h>
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| 18 |
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| 19 | |
| 20 | * itimer_get_remtime - get remaining time for the timer
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| 21 | *
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| 22 | * @timer: the timer to read
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| 23 | *
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| 24 | * Returns the delta between the expiry time and now, which can be
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| 25 | * less than zero or 1usec for an pending expired timer
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| 26 |
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| 27 | static struct timeval itimer_get_remtime(struct hrtimer *timer)
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| 28 | {
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| 29 | ktime_t rem = hrtimer_get_remaining(timer);
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| 30 |
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| 31 | |
| 32 | * Racy but safe: if the itimer expires after the above
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| 33 | * hrtimer_get_remtime() call but before this condition
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| 34 | * then we return 0 - which is correct.
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| 35 |
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| 36 | if (hrtimer_active(timer)) {
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| 37 | if (rem.tv64 <= 0)
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| 38 | rem.tv64 = NSEC_PER_USEC;
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| 39 | } else
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| 40 | rem.tv64 = 0;
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| 41 |
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| 42 | return ktime_to_timeval(rem);
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| 43 | }
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| 44 |
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| 45 | int do_getitimer(int which, struct itimerval *value)
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| 46 | {
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| 47 | struct task_struct *tsk = current;
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| 48 | cputime_t cinterval, cval;
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| 49 |
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| 50 | switch (which) {
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| 51 | case ITIMER_REAL:
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| 52 | spin_lock_irq(&tsk->sighand->siglock);
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| 53 | value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
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| 54 | value->it_interval =
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| 55 | ktime_to_timeval(tsk->signal->it_real_incr);
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| 56 | spin_unlock_irq(&tsk->sighand->siglock);
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| 57 | break;
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| 58 | case ITIMER_VIRTUAL:
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| 59 | read_lock(&tasklist_lock);
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| 60 | spin_lock_irq(&tsk->sighand->siglock);
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| 61 | cval = tsk->signal->it_virt_expires;
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| 62 | cinterval = tsk->signal->it_virt_incr;
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| 63 | if (!cputime_eq(cval, cputime_zero)) {
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| 64 | struct task_struct *t = tsk;
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| 65 | cputime_t utime = tsk->signal->utime;
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| 66 | do {
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| 67 | utime = cputime_add(utime, t->utime);
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| 68 | t = next_thread(t);
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| 69 | } while (t != tsk);
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| 70 | if (cputime_le(cval, utime)) {
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| 71 | cval = jiffies_to_cputime(1);
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| 72 | } else {
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| 73 | cval = cputime_sub(cval, utime);
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| 74 | }
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| 75 | }
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| 76 | spin_unlock_irq(&tsk->sighand->siglock);
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| 77 | read_unlock(&tasklist_lock);
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| 78 | cputime_to_timeval(cval, &value->it_value);
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| 79 | cputime_to_timeval(cinterval, &value->it_interval);
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| 80 | break;
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| 81 | case ITIMER_PROF:
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| 82 | read_lock(&tasklist_lock);
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| 83 | spin_lock_irq(&tsk->sighand->siglock);
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| 84 | cval = tsk->signal->it_prof_expires;
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| 85 | cinterval = tsk->signal->it_prof_incr;
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| 86 | if (!cputime_eq(cval, cputime_zero)) {
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| 87 | struct task_struct *t = tsk;
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| 88 | cputime_t ptime = cputime_add(tsk->signal->utime,
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| 89 | tsk->signal->stime);
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| 90 | do {
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| 91 | ptime = cputime_add(ptime,
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| 92 | cputime_add(t->utime,
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| 93 | t->stime));
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| 94 | t = next_thread(t);
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| 95 | } while (t != tsk);
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| 96 | if (cputime_le(cval, ptime)) {
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| 97 | cval = jiffies_to_cputime(1);
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| 98 | } else {
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| 99 | cval = cputime_sub(cval, ptime);
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| 100 | }
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| 101 | }
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| 102 | spin_unlock_irq(&tsk->sighand->siglock);
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| 103 | read_unlock(&tasklist_lock);
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| 104 | cputime_to_timeval(cval, &value->it_value);
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| 105 | cputime_to_timeval(cinterval, &value->it_interval);
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| 106 | break;
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| 107 | default:
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| 108 | return(-EINVAL);
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| 109 | }
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| 110 | return 0;
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| 111 | }
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| 112 |
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| 113 | asmlinkage long sys_getitimer(int which, struct itimerval __user *value)
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| 114 | {
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| 115 | int error = -EFAULT;
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| 116 | struct itimerval get_buffer;
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| 117 |
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| 118 | if (value) {
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| 119 | error = do_getitimer(which, &get_buffer);
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| 120 | if (!error &&
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| 121 | copy_to_user(value, &get_buffer, sizeof(get_buffer)))
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| 122 | error = -EFAULT;
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| 123 | }
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| 124 | return error;
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| 125 | }
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| 126 |
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| 127 |
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| 128 | |
| 129 | * The timer is automagically restarted, when interval != 0
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| 130 |
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| 131 | enum hrtimer_restart it_real_fn(struct hrtimer *timer)
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| 132 | {
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| 133 | struct signal_struct *sig =
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| 134 | container_of(timer, struct signal_struct, real_timer);
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| 135 |
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| 136 | send_group_sig_info(SIGALRM, SEND_SIG_PRIV, sig->tsk);
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| 137 |
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| 138 | return HRTIMER_NORESTART;
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| 139 | }
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| 140 |
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| 141 | |
| 142 | * We do not care about correctness. We just sanitize the values so
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| 143 | * the ktime_t operations which expect normalized values do not
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| 144 | * break. This converts negative values to long timeouts similar to
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| 145 | * the code in kernel versions < 2.6.16
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| 146 | *
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| 147 | * Print a limited number of warning messages when an invalid timeval
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| 148 | * is detected.
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| 149 |
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| 150 | static void fixup_timeval(struct timeval *tv, int interval)
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| 151 | {
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| 152 | static int warnlimit = 10;
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| 153 | unsigned long tmp;
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| 154 |
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| 155 | if (warnlimit > 0) {
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| 156 | warnlimit--;
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| 157 | printk(KERN_WARNING
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| 158 | "setitimer: %s (pid = %d) provided "
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| 159 | "invalid timeval %s: tv_sec = %ld tv_usec = %ld\n",
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| 160 | current->comm, current->pid,
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| 161 | interval ? "it_interval" : "it_value",
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| 162 | tv->tv_sec, (long) tv->tv_usec);
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| 163 | }
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| 164 |
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| 165 | tmp = tv->tv_usec;
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| 166 | if (tmp >= USEC_PER_SEC) {
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| 167 | tv->tv_usec = tmp % USEC_PER_SEC;
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| 168 | tv->tv_sec += tmp / USEC_PER_SEC;
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| 169 | }
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| 170 |
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| 171 | tmp = tv->tv_sec;
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| 172 | if (tmp > LONG_MAX)
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| 173 | tv->tv_sec = LONG_MAX;
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| 174 | }
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| 175 |
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| 176 | |
| 177 | * Returns true if the timeval is in canonical form
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| 178 |
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| 179 | #define timeval_valid(t) \
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| 180 | (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
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| 181 |
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| 182 | |
| 183 | * Check for invalid timevals, sanitize them and print a limited
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| 184 | * number of warnings.
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| 185 |
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| 186 | static void check_itimerval(struct itimerval *value) {
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| 187 |
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| 188 | if (unlikely(!timeval_valid(&value->it_value)))
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| 189 | fixup_timeval(&value->it_value, 0);
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| 190 |
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| 191 | if (unlikely(!timeval_valid(&value->it_interval)))
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| 192 | fixup_timeval(&value->it_interval, 1);
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| 193 | }
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| 194 |
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| 195 | int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
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| 196 | {
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| 197 | struct task_struct *tsk = current;
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| 198 | struct hrtimer *timer;
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| 199 | ktime_t expires;
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| 200 | cputime_t cval, cinterval, nval, ninterval;
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| 201 |
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| 202 | |
| 203 | * Validate the timevals in value.
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| 204 | *
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| 205 | * Note: Although the spec requires that invalid values shall
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| 206 | * return -EINVAL, we just fixup the value and print a limited
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| 207 | * number of warnings in order not to break users of this
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| 208 | * historical misfeature.
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| 209 | *
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| 210 | * Scheduled for replacement in March 2007
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| 211 |
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| 212 | check_itimerval(value);
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| 213 |
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| 214 | switch (which) {
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| 215 | case ITIMER_REAL:
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| 216 | again:
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| 217 | spin_lock_irq(&tsk->sighand->siglock);
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| 218 | timer = &tsk->signal->real_timer;
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| 219 | if (ovalue) {
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| 220 | ovalue->it_value = itimer_get_remtime(timer);
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| 221 | ovalue->it_interval
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| 222 | = ktime_to_timeval(tsk->signal->it_real_incr);
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| 223 | }
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| 224 |
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| 225 | if (hrtimer_try_to_cancel(timer) < 0) {
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| 226 | spin_unlock_irq(&tsk->sighand->siglock);
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| 227 | goto again;
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| 228 | }
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| 229 | expires = timeval_to_ktime(value->it_value);
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| 230 | if (expires.tv64 != 0) {
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| 231 | tsk->signal->it_real_incr =
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| 232 | timeval_to_ktime(value->it_interval);
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| 233 | hrtimer_start(timer, expires, HRTIMER_MODE_REL);
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| 234 | } else
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| 235 | tsk->signal->it_real_incr.tv64 = 0;
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| 236 |
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| 237 | spin_unlock_irq(&tsk->sighand->siglock);
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| 238 | break;
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| 239 | case ITIMER_VIRTUAL:
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| 240 | nval = timeval_to_cputime(&value->it_value);
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| 241 | ninterval = timeval_to_cputime(&value->it_interval);
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| 242 | read_lock(&tasklist_lock);
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| 243 | spin_lock_irq(&tsk->sighand->siglock);
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| 244 | cval = tsk->signal->it_virt_expires;
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| 245 | cinterval = tsk->signal->it_virt_incr;
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| 246 | if (!cputime_eq(cval, cputime_zero) ||
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| 247 | !cputime_eq(nval, cputime_zero)) {
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| 248 | if (cputime_gt(nval, cputime_zero))
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| 249 | nval = cputime_add(nval,
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| 250 | jiffies_to_cputime(1));
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| 251 | set_process_cpu_timer(tsk, CPUCLOCK_VIRT,
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| 252 | &nval, &cval);
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| 253 | }
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| 254 | tsk->signal->it_virt_expires = nval;
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| 255 | tsk->signal->it_virt_incr = ninterval;
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| 256 | spin_unlock_irq(&tsk->sighand->siglock);
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| 257 | read_unlock(&tasklist_lock);
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| 258 | if (ovalue) {
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| 259 | cputime_to_timeval(cval, &ovalue->it_value);
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| 260 | cputime_to_timeval(cinterval, &ovalue->it_interval);
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| 261 | }
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| 262 | break;
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| 263 | case ITIMER_PROF:
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| 264 | nval = timeval_to_cputime(&value->it_value);
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| 265 | ninterval = timeval_to_cputime(&value->it_interval);
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| 266 | read_lock(&tasklist_lock);
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| 267 | spin_lock_irq(&tsk->sighand->siglock);
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| 268 | cval = tsk->signal->it_prof_expires;
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| 269 | cinterval = tsk->signal->it_prof_incr;
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| 270 | if (!cputime_eq(cval, cputime_zero) ||
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| 271 | !cputime_eq(nval, cputime_zero)) {
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| 272 | if (cputime_gt(nval, cputime_zero))
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| 273 | nval = cputime_add(nval,
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| 274 | jiffies_to_cputime(1));
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| 275 | set_process_cpu_timer(tsk, CPUCLOCK_PROF,
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| 276 | &nval, &cval);
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| 277 | }
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| 278 | tsk->signal->it_prof_expires = nval;
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| 279 | tsk->signal->it_prof_incr = ninterval;
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| 280 | spin_unlock_irq(&tsk->sighand->siglock);
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| 281 | read_unlock(&tasklist_lock);
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| 282 | if (ovalue) {
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| 283 | cputime_to_timeval(cval, &ovalue->it_value);
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| 284 | cputime_to_timeval(cinterval, &ovalue->it_interval);
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| 285 | }
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| 286 | break;
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| 287 | default:
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| 288 | return -EINVAL;
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| 289 | }
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| 290 | return 0;
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| 291 | }
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| 292 |
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| 293 | |
| 294 | * alarm_setitimer - set alarm in seconds
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| 295 | *
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| 296 | * @seconds: number of seconds until alarm
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| 297 | * 0 disables the alarm
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| 298 | *
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| 299 | * Returns the remaining time in seconds of a pending timer or 0 when
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| 300 | * the timer is not active.
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| 301 | *
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| 302 | * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
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| 303 | * negative timeval settings which would cause immediate expiry.
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| 304 |
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| 305 | unsigned int alarm_setitimer(unsigned int seconds)
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| 306 | {
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| 307 | struct itimerval it_new, it_old;
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| 308 |
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| 309 | #if BITS_PER_LONG < 64
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| 310 | if (seconds > INT_MAX)
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| 311 | seconds = INT_MAX;
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| 312 | #endif
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| 313 | it_new.it_value.tv_sec = seconds;
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| 314 | it_new.it_value.tv_usec = 0;
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| 315 | it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
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| 316 |
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| 317 | do_setitimer(ITIMER_REAL, &it_new, &it_old);
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| 318 |
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| 319 | |
| 320 | * We can't return 0 if we have an alarm pending ... And we'd
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| 321 | * better return too much than too little anyway
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| 322 |
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| 323 | if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
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| 324 | it_old.it_value.tv_usec >= 500000)
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| 325 | it_old.it_value.tv_sec++;
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| 326 |
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| 327 | return it_old.it_value.tv_sec;
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| 328 | }
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| 329 |
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| 330 | asmlinkage long sys_setitimer(int which,
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| 331 | struct itimerval __user *value,
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| 332 | struct itimerval __user *ovalue)
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| 333 | {
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| 334 | struct itimerval set_buffer, get_buffer;
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| 335 | int error;
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| 336 |
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| 337 | if (value) {
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| 338 | if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
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| 339 | return -EFAULT;
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| 340 | } else
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| 341 | memset((char *) &set_buffer, 0, sizeof(set_buffer));
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| 342 |
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| 343 | error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
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| 344 | if (error || !ovalue)
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| 345 | return error;
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| 346 |
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| 347 | if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
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| 348 | return -EFAULT;
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| 349 | return 0;
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| 350 | }
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