linux/kernel/time/itimer.c
Thomas Gleixner 58c5fc2b96 time: Remove useless filenames in top level comments
Remove the pointless filenames in the top level comments. They have no
value at all and just occupy space. While at it tidy up some of the
comments and remove a stale one.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: Corey Minyard <cminyard@mvista.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: David Riley <davidriley@chromium.org>
Cc: Colin Cross <ccross@android.com>
Cc: Mark Brown <broonie@kernel.org>
Link: https://lkml.kernel.org/r/20181031182252.794898238@linutronix.de
2018-11-23 11:51:20 +01:00

339 lines
8.0 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 1992 Darren Senn
*/
/* These are all the functions necessary to implement itimers */
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/syscalls.h>
#include <linux/time.h>
#include <linux/sched/signal.h>
#include <linux/sched/cputime.h>
#include <linux/posix-timers.h>
#include <linux/hrtimer.h>
#include <trace/events/timer.h>
#include <linux/compat.h>
#include <linux/uaccess.h>
/**
* itimer_get_remtime - get remaining time for the timer
*
* @timer: the timer to read
*
* Returns the delta between the expiry time and now, which can be
* less than zero or 1usec for an pending expired timer
*/
static struct timeval itimer_get_remtime(struct hrtimer *timer)
{
ktime_t rem = __hrtimer_get_remaining(timer, true);
/*
* Racy but safe: if the itimer expires after the above
* hrtimer_get_remtime() call but before this condition
* then we return 0 - which is correct.
*/
if (hrtimer_active(timer)) {
if (rem <= 0)
rem = NSEC_PER_USEC;
} else
rem = 0;
return ktime_to_timeval(rem);
}
static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
struct itimerval *const value)
{
u64 val, interval;
struct cpu_itimer *it = &tsk->signal->it[clock_id];
spin_lock_irq(&tsk->sighand->siglock);
val = it->expires;
interval = it->incr;
if (val) {
struct task_cputime cputime;
u64 t;
thread_group_cputimer(tsk, &cputime);
if (clock_id == CPUCLOCK_PROF)
t = cputime.utime + cputime.stime;
else
/* CPUCLOCK_VIRT */
t = cputime.utime;
if (val < t)
/* about to fire */
val = TICK_NSEC;
else
val -= t;
}
spin_unlock_irq(&tsk->sighand->siglock);
value->it_value = ns_to_timeval(val);
value->it_interval = ns_to_timeval(interval);
}
int do_getitimer(int which, struct itimerval *value)
{
struct task_struct *tsk = current;
switch (which) {
case ITIMER_REAL:
spin_lock_irq(&tsk->sighand->siglock);
value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
value->it_interval =
ktime_to_timeval(tsk->signal->it_real_incr);
spin_unlock_irq(&tsk->sighand->siglock);
break;
case ITIMER_VIRTUAL:
get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
break;
case ITIMER_PROF:
get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
break;
default:
return(-EINVAL);
}
return 0;
}
SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
{
int error = -EFAULT;
struct itimerval get_buffer;
if (value) {
error = do_getitimer(which, &get_buffer);
if (!error &&
copy_to_user(value, &get_buffer, sizeof(get_buffer)))
error = -EFAULT;
}
return error;
}
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(getitimer, int, which,
struct compat_itimerval __user *, it)
{
struct itimerval kit;
int error = do_getitimer(which, &kit);
if (!error && put_compat_itimerval(it, &kit))
error = -EFAULT;
return error;
}
#endif
/*
* The timer is automagically restarted, when interval != 0
*/
enum hrtimer_restart it_real_fn(struct hrtimer *timer)
{
struct signal_struct *sig =
container_of(timer, struct signal_struct, real_timer);
struct pid *leader_pid = sig->pids[PIDTYPE_TGID];
trace_itimer_expire(ITIMER_REAL, leader_pid, 0);
kill_pid_info(SIGALRM, SEND_SIG_PRIV, leader_pid);
return HRTIMER_NORESTART;
}
static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
const struct itimerval *const value,
struct itimerval *const ovalue)
{
u64 oval, nval, ointerval, ninterval;
struct cpu_itimer *it = &tsk->signal->it[clock_id];
/*
* Use the to_ktime conversion because that clamps the maximum
* value to KTIME_MAX and avoid multiplication overflows.
*/
nval = ktime_to_ns(timeval_to_ktime(value->it_value));
ninterval = ktime_to_ns(timeval_to_ktime(value->it_interval));
spin_lock_irq(&tsk->sighand->siglock);
oval = it->expires;
ointerval = it->incr;
if (oval || nval) {
if (nval > 0)
nval += TICK_NSEC;
set_process_cpu_timer(tsk, clock_id, &nval, &oval);
}
it->expires = nval;
it->incr = ninterval;
trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
spin_unlock_irq(&tsk->sighand->siglock);
if (ovalue) {
ovalue->it_value = ns_to_timeval(oval);
ovalue->it_interval = ns_to_timeval(ointerval);
}
}
/*
* 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))
int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
{
struct task_struct *tsk = current;
struct hrtimer *timer;
ktime_t expires;
/*
* Validate the timevals in value.
*/
if (!timeval_valid(&value->it_value) ||
!timeval_valid(&value->it_interval))
return -EINVAL;
switch (which) {
case ITIMER_REAL:
again:
spin_lock_irq(&tsk->sighand->siglock);
timer = &tsk->signal->real_timer;
if (ovalue) {
ovalue->it_value = itimer_get_remtime(timer);
ovalue->it_interval
= ktime_to_timeval(tsk->signal->it_real_incr);
}
/* We are sharing ->siglock with it_real_fn() */
if (hrtimer_try_to_cancel(timer) < 0) {
spin_unlock_irq(&tsk->sighand->siglock);
goto again;
}
expires = timeval_to_ktime(value->it_value);
if (expires != 0) {
tsk->signal->it_real_incr =
timeval_to_ktime(value->it_interval);
hrtimer_start(timer, expires, HRTIMER_MODE_REL);
} else
tsk->signal->it_real_incr = 0;
trace_itimer_state(ITIMER_REAL, value, 0);
spin_unlock_irq(&tsk->sighand->siglock);
break;
case ITIMER_VIRTUAL:
set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
break;
case ITIMER_PROF:
set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
break;
default:
return -EINVAL;
}
return 0;
}
#ifdef __ARCH_WANT_SYS_ALARM
/**
* 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.
*/
static 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;
}
/*
* For backwards compatibility? This can be done in libc so Alpha
* and all newer ports shouldn't need it.
*/
SYSCALL_DEFINE1(alarm, unsigned int, seconds)
{
return alarm_setitimer(seconds);
}
#endif
SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
struct itimerval __user *, ovalue)
{
struct itimerval set_buffer, get_buffer;
int error;
if (value) {
if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
return -EFAULT;
} else {
memset(&set_buffer, 0, sizeof(set_buffer));
printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
" Misfeature support will be removed\n",
current->comm);
}
error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
if (error || !ovalue)
return error;
if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
return -EFAULT;
return 0;
}
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE3(setitimer, int, which,
struct compat_itimerval __user *, in,
struct compat_itimerval __user *, out)
{
struct itimerval kin, kout;
int error;
if (in) {
if (get_compat_itimerval(&kin, in))
return -EFAULT;
} else {
memset(&kin, 0, sizeof(kin));
}
error = do_setitimer(which, &kin, out ? &kout : NULL);
if (error || !out)
return error;
if (put_compat_itimerval(out, &kout))
return -EFAULT;
return 0;
}
#endif