mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 10:49:33 +00:00
![Stanislaw Gruszka](/assets/img/avatar_default.png)
incr_error and error fields of struct cpu_itimer are used when calculating next timer tick in check_cpu_itimers() and should not be modified without tsk->sighand->siglock taken. Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com> LKML-Reference: <1253802903-979-1-git-send-email-sgruszka@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
298 lines
7.3 KiB
C
298 lines
7.3 KiB
C
/*
|
|
* linux/kernel/itimer.c
|
|
*
|
|
* 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/posix-timers.h>
|
|
#include <linux/hrtimer.h>
|
|
#include <trace/events/timer.h>
|
|
|
|
#include <asm/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);
|
|
|
|
/*
|
|
* 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.tv64 <= 0)
|
|
rem.tv64 = NSEC_PER_USEC;
|
|
} else
|
|
rem.tv64 = 0;
|
|
|
|
return ktime_to_timeval(rem);
|
|
}
|
|
|
|
static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
|
|
struct itimerval *const value)
|
|
{
|
|
cputime_t cval, cinterval;
|
|
struct cpu_itimer *it = &tsk->signal->it[clock_id];
|
|
|
|
spin_lock_irq(&tsk->sighand->siglock);
|
|
|
|
cval = it->expires;
|
|
cinterval = it->incr;
|
|
if (!cputime_eq(cval, cputime_zero)) {
|
|
struct task_cputime cputime;
|
|
cputime_t t;
|
|
|
|
thread_group_cputimer(tsk, &cputime);
|
|
if (clock_id == CPUCLOCK_PROF)
|
|
t = cputime_add(cputime.utime, cputime.stime);
|
|
else
|
|
/* CPUCLOCK_VIRT */
|
|
t = cputime.utime;
|
|
|
|
if (cputime_le(cval, t))
|
|
/* about to fire */
|
|
cval = cputime_one_jiffy;
|
|
else
|
|
cval = cputime_sub(cval, t);
|
|
}
|
|
|
|
spin_unlock_irq(&tsk->sighand->siglock);
|
|
|
|
cputime_to_timeval(cval, &value->it_value);
|
|
cputime_to_timeval(cinterval, &value->it_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;
|
|
}
|
|
|
|
|
|
/*
|
|
* 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);
|
|
|
|
trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0);
|
|
kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
|
|
|
|
return HRTIMER_NORESTART;
|
|
}
|
|
|
|
static inline u32 cputime_sub_ns(cputime_t ct, s64 real_ns)
|
|
{
|
|
struct timespec ts;
|
|
s64 cpu_ns;
|
|
|
|
cputime_to_timespec(ct, &ts);
|
|
cpu_ns = timespec_to_ns(&ts);
|
|
|
|
return (cpu_ns <= real_ns) ? 0 : cpu_ns - real_ns;
|
|
}
|
|
|
|
static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
|
|
const struct itimerval *const value,
|
|
struct itimerval *const ovalue)
|
|
{
|
|
cputime_t cval, nval, cinterval, ninterval;
|
|
s64 ns_ninterval, ns_nval;
|
|
u32 error, incr_error;
|
|
struct cpu_itimer *it = &tsk->signal->it[clock_id];
|
|
|
|
nval = timeval_to_cputime(&value->it_value);
|
|
ns_nval = timeval_to_ns(&value->it_value);
|
|
ninterval = timeval_to_cputime(&value->it_interval);
|
|
ns_ninterval = timeval_to_ns(&value->it_interval);
|
|
|
|
error = cputime_sub_ns(nval, ns_nval);
|
|
incr_error = cputime_sub_ns(ninterval, ns_ninterval);
|
|
|
|
spin_lock_irq(&tsk->sighand->siglock);
|
|
|
|
cval = it->expires;
|
|
cinterval = it->incr;
|
|
if (!cputime_eq(cval, cputime_zero) ||
|
|
!cputime_eq(nval, cputime_zero)) {
|
|
if (cputime_gt(nval, cputime_zero))
|
|
nval = cputime_add(nval, cputime_one_jiffy);
|
|
set_process_cpu_timer(tsk, clock_id, &nval, &cval);
|
|
}
|
|
it->expires = nval;
|
|
it->incr = ninterval;
|
|
it->error = error;
|
|
it->incr_error = incr_error;
|
|
trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
|
|
ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
|
|
|
|
spin_unlock_irq(&tsk->sighand->siglock);
|
|
|
|
if (ovalue) {
|
|
cputime_to_timeval(cval, &ovalue->it_value);
|
|
cputime_to_timeval(cinterval, &ovalue->it_interval);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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.tv64 != 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.tv64 = 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;
|
|
}
|
|
|
|
/**
|
|
* 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;
|
|
}
|
|
|
|
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((char *) &set_buffer, 0, sizeof(set_buffer));
|
|
|
|
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;
|
|
}
|