diff options
Diffstat (limited to 'kernel/itimer.c')
| -rw-r--r-- | kernel/itimer.c | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/kernel/itimer.c b/kernel/itimer.c index 379be2f8c84..680e6b70c87 100644 --- a/kernel/itimer.c +++ b/kernel/itimer.c @@ -143,6 +143,60 @@ int it_real_fn(void *data) return HRTIMER_NORESTART; } +/* + * We do not care about correctness. We just sanitize the values so + * the ktime_t operations which expect normalized values do not + * break. This converts negative values to long timeouts similar to + * the code in kernel versions < 2.6.16 + * + * Print a limited number of warning messages when an invalid timeval + * is detected. + */ +static void fixup_timeval(struct timeval *tv, int interval) +{ + static int warnlimit = 10; + unsigned long tmp; + + if (warnlimit > 0) { + warnlimit--; + printk(KERN_WARNING + "setitimer: %s (pid = %d) provided " + "invalid timeval %s: tv_sec = %ld tv_usec = %ld\n", + current->comm, current->pid, + interval ? "it_interval" : "it_value", + tv->tv_sec, (long) tv->tv_usec); + } + + tmp = tv->tv_usec; + if (tmp >= USEC_PER_SEC) { + tv->tv_usec = tmp % USEC_PER_SEC; + tv->tv_sec += tmp / USEC_PER_SEC; + } + + tmp = tv->tv_sec; + if (tmp > LONG_MAX) + tv->tv_sec = LONG_MAX; +} + +/* + * Returns true if the timeval is in canonical form + */ +#define timeval_valid(t) \ + (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC)) + +/* + * Check for invalid timevals, sanitize them and print a limited + * number of warnings. + */ +static void check_itimerval(struct itimerval *value) { + + if (unlikely(!timeval_valid(&value->it_value))) + fixup_timeval(&value->it_value, 0); + + if (unlikely(!timeval_valid(&value->it_interval))) + fixup_timeval(&value->it_interval, 1); +} + int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue) { struct task_struct *tsk = current; @@ -150,6 +204,18 @@ int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue) ktime_t expires; cputime_t cval, cinterval, nval, ninterval; + /* + * Validate the timevals in value. + * + * Note: Although the spec requires that invalid values shall + * return -EINVAL, we just fixup the value and print a limited + * number of warnings in order not to break users of this + * historical misfeature. + * + * Scheduled for replacement in March 2007 + */ + check_itimerval(value); + switch (which) { case ITIMER_REAL: again: @@ -226,6 +292,43 @@ again: return 0; } +/** + * alarm_setitimer - set alarm in seconds + * + * @seconds: number of seconds until alarm + * 0 disables the alarm + * + * Returns the remaining time in seconds of a pending timer or 0 when + * the timer is not active. + * + * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid + * negative timeval settings which would cause immediate expiry. + */ +unsigned int alarm_setitimer(unsigned int seconds) +{ + struct itimerval it_new, it_old; + +#if BITS_PER_LONG < 64 + if (seconds > INT_MAX) + seconds = INT_MAX; +#endif + it_new.it_value.tv_sec = seconds; + it_new.it_value.tv_usec = 0; + it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0; + + do_setitimer(ITIMER_REAL, &it_new, &it_old); + + /* + * We can't return 0 if we have an alarm pending ... And we'd + * better return too much than too little anyway + */ + if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) || + it_old.it_value.tv_usec >= 500000) + it_old.it_value.tv_sec++; + + return it_old.it_value.tv_sec; +} + asmlinkage long sys_setitimer(int which, struct itimerval __user *value, struct itimerval __user *ovalue) |