/*
* Implement CPU time clocks for the POSIX clock interface.
*/
#include <linux/sched.h>
#include <linux/posix-timers.h>
#include <asm/uaccess.h>
#include <linux/errno.h>
static int check_clock(clockid_t which_clock)
{
int error = 0;
struct task_struct *p;
const pid_t pid = CPUCLOCK_PID(which_clock);
if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
return -EINVAL;
if (pid == 0)
return 0;
read_lock(&tasklist_lock);
p = find_task_by_pid(pid);
if (!p || (CPUCLOCK_PERTHREAD(which_clock) ?
p->tgid != current->tgid : p->tgid != pid)) {
error = -EINVAL;
}
read_unlock(&tasklist_lock);
return error;
}
static inline union cpu_time_count
timespec_to_sample(clockid_t which_clock, const struct timespec *tp)
{
union cpu_time_count ret;
ret.sched = 0; /* high half always zero when .cpu used */
if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
ret.sched = tp->tv_sec * NSEC_PER_SEC + tp->tv_nsec;
} else {
ret.cpu = timespec_to_cputime(tp);
}
return ret;
}
static void sample_to_timespec(clockid_t which_clock,
union cpu_time_count cpu,
struct timespec *tp)
{
if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
tp->tv_sec = div_long_long_rem(cpu.sched,
NSEC_PER_SEC, &tp->tv_nsec);
} else {
cputime_to_timespec(cpu.cpu, tp);
}
}
static inline int cpu_time_before(clockid_t which_clock,
union cpu_time_count now,
union cpu_time_count then)
{
if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
return now.sched < then.sched;
} else {
return cputime_lt(now.cpu, then.cpu);
}
}
static inline void cpu_time_add(clockid_t which_clock,
union cpu_time_count *acc,
union cpu_time_count val)
{
if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
acc->sched += val.sched;
} else {
acc->cpu = cputime_add(acc->cpu, val.cpu);
}
}
static inline union cpu_time_count cpu_time_sub(clockid_t which_clock,
union cpu_time_count a,
union cpu_time_count b)
{
if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
a.sched -= b.sched;
} else {
a.cpu = cputime_sub(a.cpu, b.cpu);
}
return a;
}
/*
* Update expiry time from increment, and increase overrun count,
* given the current clock sample.
*/
static inline void bump_cpu_timer(struct k_itimer *timer,
union cpu_time_count now)
{
int i;
if (timer->it.cpu.incr.sched == 0)
return;
if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
unsigned long long delta, incr;
if (now.sched < timer->it.cpu.expires.sched)
return;
incr = timer->it.cpu.incr.sched;
delta = now.sched + incr - timer->it.cpu.expires.sched;
/* Don't use (incr*2 < delta), incr*2 might overflow. */
for (i = 0; incr < delta - incr; i++)
incr = incr << 1;
for (; i >= 0; incr >>= 1, i--) {
if (delta <= incr)
continue;
timer->it.cpu.expires.sched += incr;
timer->it_overrun += 1 << i;
delta -= incr;
}
} else {
cputime_t delta, incr;
if (cputime_lt(now.cpu, timer->it.cpu.expires.cpu))
return;
incr = timer->it.cpu.incr.cpu;
delta = cputime_sub(cputime_add(now.cpu, incr),
timer->it.cpu.expires.cpu);
/* Don't use (incr*2 < delta), incr*2 might overflow. */
for (i = 0; cputime_lt(incr, cputime_sub(delta, incr)); i++)
incr = cputime_add(incr, incr);
for (; i >= 0; incr = cputime_halve(incr), i--) {
if (cputime_le(delta, incr))
continue;
timer->it.cpu.expires.cpu =
cputime_add(timer->it.cpu.expires.cpu, incr);
timer->it_overrun += 1 << i;
delta = cputime_sub(delta, incr);
}
}
}
static inline cputime_t prof_ticks(struct task_struct *p)
{
return cputime_add(p->utime, p->stime);
}
static inline cputime_t virt_ticks(struct task_struct *p)
{
return p->utime;
}
static inline unsigned long long sched_ns(struct task_struct *p)
{
return (p == current) ? current_sched_time(p) : p->sched_time;
}
int posix_cpu_clock_getres(clockid_t which_clock, struct timespec *tp)
{
int error = check_clock(which_clock);
if (!error) {
tp->tv_sec = 0;
tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
/*
* If sched_clock is using a cycle counter, we
* don't have any idea of its true resolution
* exported, but it is much more than 1s/HZ.
*/
tp->tv_nsec = 1;
}
}
return error;
}
int posix_cpu_clock_set(clockid_t which_clock, const struct timespec *tp)
{
/*
* You can never reset a CPU clock, but we check for other errors
* in the call before failing with EPERM.
*/
int error = check_clock(which_clock);
if (error == 0) {
error = -EPERM;
}
return error;
}
/*
* Sample a per-thread clock for the given task.
*/
static int cpu_clock_sample(clockid_t which_clock, struct task_struct *p,
union cpu_time_count *cpu)
{
switch (CPUCLOCK_WHICH(which_clock)) {
default:
return -EINVAL;
case CPUCLOCK_PROF:
cpu->cpu = prof_ticks(p);
break;
case CPUCLOCK_VIRT:
cpu->cpu = virt_ticks(p);
break;
case CPUCLOCK_SCHED:
cpu->sched = sched_ns(p);
break;
}
return 0;
}
/*
* Sample a process (thread group) clock for the given group_leader task.
* Must be called with tasklist_lock held for reading.
* Must be called with tasklist_lock held for reading, and p->sighand->siglock.
*/
static int cpu_clock_sample_group_locked(unsigned int clock_idx,
struct task_struct *p,
union cpu_time_count *cpu)
{
struct task_struct *t = p;
switch (clock_idx) {
default:
return -EINVAL;
case CPUCLOCK_PROF:
cpu->cpu = cputime_add(p->signal->utime, p->signal->stime);
do {
cpu->cpu = cputime_add(cpu->cpu, prof_ticks(t));
t = next_thread(t);
} while (t != p);
break;
case CPUCLOCK_VIRT:
cpu->cpu = p->signal->utime;
do {
cpu->cpu = cputime_add(cpu->cpu, virt_ticks(t));
t = next_thread(t);
} while (t != p);
break;
case CPUCLOCK_SCHED:
cpu->sched = p->signal->sched_time;
/* Add in each other live thread. */
while ((t = next_thread(t)) != p) {
cpu->sched += t->sched_time;
}
if (p->tgid == current->tgid) {
/*
* We're sampling ourselves, so include the
* cycles not yet banked. We still omit
* other threads running on other CPUs,
* so the total can always be behind as
* much as max(nthreads-1,ncpus) * (NSEC_PER_SEC/HZ).
*/
cpu->sched += current_sched_time(current);
} else {
cpu->sched += p->sched_time;
}
break;
}
return 0;
}
/*
* Sample a process (thread group) clock for the given group_leader task.
* Must be called with tasklist_lock held for reading.
*/
static int cpu_clock_sample_group(clockid_t which_clock,
struct task_struct *p,
union cpu_time_count *cpu)
{
int ret;
unsigned long flags;
spin_lock_irqsave(&p->sighand->siglock, flags);
ret = cpu_clock_sample_group_locked(CPUCLOCK_WHICH(which_clock), p,
cpu);
spin_unlock_irqrestore(&p->sighand->siglock, flags);
return ret;
}
int posix_cpu_clock_get(clockid_t which_clock, struct timespec *tp)
{
const pid_t pid = CPUCLOCK_PID(which_clock);
int error = -EINVAL;
union cpu_time_count rtn;
if (pid == 0) {
/*
* Special case constant value for our own clocks.
* We don't have to do any lookup to find ourselves.
*/
if (CPUCLOCK_PERTHREAD(which_clock)) {
/*
* Sampling just ourselves we can do with no locking.
*/
error = cpu_clock_sample(which_clock,
current, &rtn);
} else {
read_lock(&tasklist_lock);
error = cpu_clock_sample_group(which_clock,
current, &rtn);
read_unlock(&tasklist_lock);
}
} else {
/*
* Find the given PID, and validate that the caller
* should be able to see it.
*/
struct task_struct *p;
read_lock(&tasklist_lock);
p = find_task_by_pid(pid);
if (p) {
if (CPUCLOCK_PERTHREAD(which_clock)) {
if (p->tgid == current->tgid) {
error = cpu_clock_sample(which_clock,
p, &rtn);
}
} else if (p->tgid == pid && p->signal) {
error = cpu_clock_sample_group(which_clock,
p, &rtn);
}
}
read_unlock(&tasklist_lock);
}
if (error)
return error;
sample_to_timespec(which_clock, rtn, tp);
return 0;
}
/*
* Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
* This is called from sys_timer_create with the new timer already locked.
*/
int posix_cpu_timer_create(struct k_itimer *new_timer)
{
int ret = 0;
const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
struct task_struct *p;
if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
return -EINVAL;
INIT_LIST_HEAD(&new_timer->it.cpu.entry);
new_timer->it.cpu.incr.sched = 0;
new_timer->it.cpu.expires.sched = 0;
read_lock(&tasklist_lock);
if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
if (pid == 0) {
p = current;
} else {
p = find_task_by_pid(pid);
if (p && p->tgid != current->tgid)
p = NULL;
}
} else {
if (pid == 0) {
p = current->group_leader;
} else {
p = find_task_by_pid(pid);
if (p && p->tgid != pid)
p = NULL;
}
}
new_timer->it.cpu.task = p;
if (p) {
get_task_struct(p);
} else {
ret = -EINVAL;
}
read_unlock(&tasklist_lock);
return ret;
}
/*
* Clean up a CPU-clock timer that is about to be destroyed.
* This is called from timer deletion with the timer already locked.
* If we return TIMER_RETRY, it's necessary to release the timer's lock
* and try again. (This happens when the timer is in the middle of firing.)
*/
int posix_cpu_timer_del(struct k_itimer *timer)
{
struct task_struct *p = timer->it.cpu.task;
if (timer->it.cpu.firing)
return TIMER_RETRY;
if (unlikely(p == NULL))
return 0;
spin_lock(&p->sighand->siglock);
if (!list_empty(&timer->it.cpu.entry)) {
/*
* Take us off the task's timer list. We don't need to
* take tasklist_lock and check for the task being reaped.
* If it was reaped, it already called posix_cpu_timers_exit
* and posix_cpu_timers_exit_group to clear all the timers
* that pointed to it.
*/
list_del(&timer->it.cpu.entry);
put_task_struct(p);
}
spin_unlock(&p->sighand->siglock);
return 0;
}
/*
* Clean out CPU timers still ticking when a thread exited. The task
* pointer is cleared, and the expiry time is replaced with the residual
* time for later timer_gettime calls to return.
* This must be called with the siglock held.
*/
static void cleanup_timers(struct list_head *head,
cputime_t utime, cputime_t stime,
unsigned long long sched_time)
{
struct cpu_timer_list *timer, *next;
cputime_t ptime = cputime_add(utime, stime);
list_for_each_entry_safe(timer, next, head, entry) {
put_task_struct(timer->task);
timer->task = NULL;
list_del_init(&timer->entry);
if (cputime_lt(timer->expires.cpu, ptime)) {
timer->expires.cpu = cputime_zero;
} else {
timer->expires.cpu = cputime_sub(timer->expires.cpu,
ptime);
}
}
++head;
list_for_each_entry_safe(timer, next, head, entry) {
put_task_struct(timer->task);
timer->task = NULL;
list_del_init(&timer->entry);
if (cputime_lt(timer->expires.cpu, utime)) {
timer->expires.cpu = cputime_zero;
} else {
timer->expires.cpu = cputime_sub(timer->expires.cpu,
utime);
}
}
++head;
list_for_each_entry_safe(timer, next, head, entry) {
put_task_struct(timer->task);
timer->task = NULL;
list_del_init(&timer->entry);
if (timer->expires.sched < sched_time) {
timer->expires.sched = 0;
} else {
timer->expires.sched -= sched_time;
}
}
}
/*
* These are both called with the siglock held, when the current thread
* is being reaped. When the final (leader) thread in the group is reaped,
* posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
*/
void posix_cpu_timers_exit(struct task_struct *tsk)
{
cleanup_timers(tsk->cpu_timers,
tsk->utime, tsk->stime, tsk->sched_time);
}
void posix_cpu_timers_exit_group(struct task_struct *tsk)
{
cleanup_timers(tsk->signal->cpu_timers,
cputime_add(tsk->utime, tsk->signal->utime),
cputime_add(tsk->stime, tsk->signal->stime),
tsk->sched_time + tsk->signal->sched_time);
}
/*
* Set the expiry times of all the threads in the process so one of them
* will go off before the process cumulative expiry total is reached.
*/
static void process_timer_rebalance(struct task_struct *p,
unsigned int clock_idx,
union cpu_time_count expires,
union cpu_time_count val)
{
cputime_t ticks, left;
unsigned long long ns, nsleft;
struct task_struct *t = p;
unsigned int nthreads = atomic_read(&p->signal->live);
switch (clock_idx) {
default:
BUG();
break;
case CPUCLOCK_PROF:
left = cputime_div(cputime_sub(expires.cpu, val.cpu),
nthreads);
do {
if (!unlikely(t->exit_state)) {
ticks = cputime_add(prof_ticks(t), left);
if (cputime_eq(t->it_prof_expires,
cputime_zero) ||
cputime_gt(t->it_prof_expires, ticks)) {
t->it_prof_expires = ticks;
}
}
t = next_thread(t);
} while (t != p);
break;
case CPUCLOCK_VIRT:
left = cputime_div(cputime_sub(expires.cpu, val.cpu),
nthreads);
do {
if (!unlikely(t->exit_state)) {
ticks = cputime_add(virt_ticks(t), left);
if (cputime_eq(t->it_virt_expires,
cputime_zero) ||
cputime_gt(t->it_virt_expires, ticks)) {
t->it_virt_expires = ticks;
}
}
t = next_thread(t);
} while (t != p);
break;
case CPUCLOCK_SCHED:
nsleft = expires.sched - val.sched;
do_div(nsleft, nthreads);
do {
if (!unlikely(t->exit_state)) {
ns = t->sched_time + nsleft;
if (t->it_sched_expires == 0 ||
t->it_sched_expires > ns) {
t->it_sched_expires = ns;
}
}
t = next_thread(t);
} while (t != p);
break;
}
}
static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
{
/*
* That's all for this thread or process.
* We leave our residual in expires to be reported.
*/
put_task_struct(timer->it.cpu.task);
timer->it.cpu.task = NULL;
timer->it.cpu.expires = cpu_time_sub(timer->it_clock,
timer->it.cpu.expires,
now);
}
/*
* Insert the timer on the appropriate list before any timers that
* expire later. This must be called with the tasklist_lock held
* for reading, and interrupts disabled.
*/
static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
{
struct task_struct *p = timer->it.cpu.task;
struct list_head *head, *listpos;
struct cpu_timer_list *const nt = &timer->it.cpu;
struct cpu_timer_list *next;
unsigned long i;
head = (CPUCLOCK_PERTHREAD(timer->it_clock) ?
p->cpu_timers : p->signal->cpu_timers);
head += CPUCLOCK_WHICH(timer->it_clock);
BUG_ON(!irqs_disabled());
spin_lock(&p->sighand->siglock);
listpos = head;
if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
list_for_each_entry(next, head, entry) {
if (next->expires.sched > nt->expires.sched) {
listpos = &next->entry;
break;
}
}
} else {
list_for_each_entry(next, head, entry) {
if (cputime_gt(next->expires.cpu, nt->expires.cpu)) {
listpos = &next->entry;
break;
}
}
}
list_add(&nt->entry, listpos);
if (listpos == head) {
/*
* We are the new earliest-expiring timer.
* If we are a thread timer, there can always
* be a process timer telling us to stop earlier.
*/
if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
switch (CPUCLOCK_WHICH(timer->it_clock)) {
default:
BUG();
case CPUCLOCK_PROF:
if (cputime_eq(p->it_prof_expires,
cputime_zero) ||
cputime_gt(p->it_prof_expires,
nt->expires.cpu))
p->it_prof_expires = nt->expires.cpu;
break;
case CPUCLOCK_VIRT:
if (cputime_eq(p->it_virt_expires,
cputime_zero) ||
cputime_gt(p->it_virt_expires,
nt->expires.cpu))
p->it_virt_expires = nt->expires.cpu;
break;
case CPUCLOCK_SCHED:
if (p->it_sched_expires == 0 ||
p->it_sched_expires > nt->expires.sched)
p->it_sched_expires = nt->expires.sched;
break;
}
} else {
/*
* For a process timer, we must balance
* all the live threads' expirations.
*/
switch (CPUCLOCK_WHICH(timer->it_clock)) {
default:
BUG();
case CPUCLOCK_VIRT:
if (!cputime_eq(p->signal->it_virt_expires,
cputime_zero) &&
cputime_lt(p->signal->it_virt_expires,
timer->it.cpu.expires.cpu))
break;
goto rebalance;
case CPUCLOCK_PROF:
if (!cputime_eq(p->signal->it_prof_expires,
cputime_zero) &&
cputime_lt(p->signal->it_prof_expires,
timer->it.cpu.expires.cpu))
break;
i = p->signal->rlim[RLIMIT_CPU].rlim_cur;
if (i != RLIM_INFINITY &&
i <= cputime_to_secs(timer->it.cpu.expires.cpu))
break;
goto rebalance;
case CPUCLOCK_SCHED:
rebalance:
process_timer_rebalance(
timer->it.cpu.task,
CPUCLOCK_WHICH(timer->it_clock),
timer->it.cpu.expires, now);
break;
}
}
}
spin_unlock(&p->sighand->siglock);
}
/*
* The timer is locked, fire it and arrange for its reload.
*/
static void cpu_timer_fire(struct k_itimer *timer)
{
if (unlikely(timer->sigq == NULL)) {
/*
* This a special case for clock_nanosleep,
* not a normal timer from sys_timer_create.
*/
wake_up_process(timer->it_process);
timer->it.cpu.expires.sched = 0;
} else if (timer->it.cpu.incr.sched == 0) {
/*
* One-shot timer. Clear it as soon as it's fired.
*/
posix_timer_event(timer, 0);
timer->it.cpu.expires.sched = 0;
} else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
/*
* The signal did not get queued because the signal
* was ignored, so we won't get any callback to
* reload the timer. But we need to keep it
* ticking in case the signal is deliverable next time.
*/
posix_cpu_timer_schedule(timer);
}
}
/*
* Guts of sys_timer_settime for CPU timers.
* This is called with the timer locked and interrupts disabled.
* If we return TIMER_RETRY, it's necessary to release the timer's lock
* and try again. (This happens when the timer is in the middle of firing.)
*/
int posix_cpu_timer_set(struct k_itimer *timer, int flags,
struct itimerspec *new, struct itimerspec *old)
{
struct task_struct *p = timer->it.cpu.task;
union cpu_time_count old_expires, new_expires, val;
int ret;
if (unlikely(p == NULL)) {
/*
* Timer refers to a dead task's clock.
*/
return -ESRCH;
}
new_expires = timespec_to_sample(timer->it_clock, &new->it_value);
read_lock(&tasklist_lock);
/*
* We need the tasklist_lock to protect against reaping that
* clears p->signal. If p has just been reaped, we can no
* longer get any information about it at all.
*/
if (unlikely(p->signal == NULL)) {
read_unlock(&tasklist_lock);
put_task_struct(p);
timer->it.cpu.task = NULL;
return -ESRCH;
}
/*
* Disarm any old timer after extracting its expiry time.
*/
BUG_ON(!irqs_disabled());
spin_lock(&p->sighand->siglock);
old_expires = timer->it.cpu.expires;
list_del_init(&timer->it.cpu.entry);
spin_unlock(&p->sighand->siglock);
/*
* We need to sample the current value to convert the new
* value from to relative and absolute, and to convert the
* old value from absolute to relative. To set a process
* timer, we need a sample to balance the thread expiry
* times (in arm_timer). With an absolute time, we must
* check if it's already passed. In short, we need a sample.
*/
if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
cpu_clock_sample(timer->it_clock, p, &val);
} else {
cpu_clock_sample_group(timer->it_clock, p, &val);
}
if (old) {
if (old_expires.sched == 0) {
old->it_value.tv_sec = 0;
old->it_value.tv_nsec = 0;
} else {
/*
* Update the timer in case it has
* overrun already. If it has,
* we'll report it as having overrun
* and with the next reloaded timer
* already ticking, though we are
* swallowing that pending
* notification here to install the
* new setting.
*/
bump_cpu_timer(timer, val);
if (cpu_time_before(timer->it_clock, val,
timer->it.cpu.expires)) {
old_expires = cpu_time_sub(
timer->it_clock,
timer->it.cpu.expires, val);
sample_to_timespec(timer->it_clock,
old_expires,
&old->it_value);
} else {
old->it_value.tv_nsec = 1;
old->it_value.tv_sec = 0;
}
}
}
if (unlikely(timer->it.cpu.firing)) {
/*
* We are colliding with the timer actually firing.
* Punt after filling in the timer's old value, and
* disable this firing since we are already reporting
* it as an overrun (thanks to bump_cpu_timer above).
*/
read_unlock(&tasklist_lock);
timer->it.cpu.firing = -1;
ret = TIMER_RETRY;
goto out;
}
if (new_expires.sched != 0 && !(flags & TIMER_ABSTIME)) {
cpu_time_add(timer->it_clock, &new_expires, val);
}
/*
* Install the new expiry time (or zero).
* For a timer with no notification action, we don't actually
* arm the timer (we'll just fake it for timer_gettime).
*/
timer->it.cpu.expires = new_expires;
if (new_expires.sched != 0 &&
(timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
cpu_time_before(timer->it_clock, val, new_expires)) {
arm_timer(timer, val);
}
read_unlock(&tasklist_lock);
/*
* Install the new reload setting, and
* set up the signal and overrun bookkeeping.
*/
timer->it.cpu.incr = timespec_to_sample(timer->it_clock,
&new->it_interval);
/*
* This acts as a modification timestamp for the timer,
* so any automatic reload attempt will punt on seeing
* that we have reset the timer manually.
*/
timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
~REQUEUE_PENDING;
timer->it_overrun_last = 0;
timer->it_overrun = -1;
if (new_expires.sched != 0 &&
(timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
!cpu_time_before(timer->it_clock, val, new_expires)) {
/*
* The designated time already passed, so we notify
* immediately, even if the thread never runs to
* accumulate more time on this clock.
*/
cpu_timer_fire(timer);
}
ret = 0;
out:
if (old) {
sample_to_timespec(timer->it_clock,
timer->it.cpu.incr, &old->it_interval);
}
return ret;
}
void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
{
union cpu_time_count now;
struct task_struct *p = timer->it.cpu.task;
int clear_dead;
/*
* Easy part: convert the reload time.
*/
sample_to_timespec(timer->it_clock,
timer->it.cpu.incr, &itp->it_interval);
if (timer->it.cpu.expires.sched == 0) { /* Timer not armed at all. */
itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
return;
}
if (unlikely(p == NULL)) {
/*
* This task already died and the timer will never fire.
* In this case, expires is actually the dead value.
*/
dead:
sample_to_timespec(timer->it_clock, timer->it.cpu.expires,
&itp->it_value);
return;
}
/*
* Sample the clock to take the difference with the expiry time.
*/
if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
cpu_clock_sample(timer->it_clock, p, &now);
clear_dead = p->exit_state;
} else {
read_lock(&tasklist_lock);
if (unlikely(p->signal == NULL)) {
/*
* The process has been reaped.
* We can't even collect a sample any more.
* Call the timer disarmed, nothing else to do.
*/
put_task_struct(p);
timer->it.cpu.task = NULL;
timer->it.cpu.expires.sched = 0;
read_unlock(&tasklist_lock);
goto dead;
} else {
cpu_clock_sample_group(timer->it_clock, p, &now);
clear_dead = (unlikely(p->exit_state) &&
thread_group_empty(p));
}
read_unlock(&tasklist_lock);
}
if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
if (timer->it.cpu.incr.sched == 0 &&
cpu_time_before(timer->it_clock,
timer->it.cpu.expires, now)) {
/*
* Do-nothing timer expired and has no reload,
* so it's as if it was never set.
*/
timer->it.cpu.expires.sched = 0;
itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
return;
}
/*
* Account for any expirations and reloads that should
* have happened.
*/
bump_cpu_timer(timer, now);
}
if (unlikely(clear_dead)) {
/*
* We've noticed that the thread is dead, but
* not yet reaped. Take this opportunity to
* drop our task ref.
*/
clear_dead_task(timer, now);
goto dead;
}
if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) {
sample_to_timespec(timer->it_clock,
cpu_time_sub(timer->it_clock,
timer->it.cpu.expires, now),
&itp->it_value);
} else {
/*
* The timer should have expired already, but the firing
* hasn't taken place yet. Say it's just about to expire.
*/
itp->it_value.tv_nsec = 1;
itp->it_value.tv_sec = 0;
}
}
/*
* Check for any per-thread CPU timers that have fired and move them off
* the tsk->cpu_timers[N] list onto the firing list. Here we update the
* tsk->it_*_expires values to reflect the remaining thread CPU timers.
*/
static void check_thread_timers(struct task_struct *tsk,
struct list_head *firing)
{
struct list_head *timers = tsk->cpu_timers;
tsk->it_prof_expires = cputime_zero;
while (!list_empty(timers)) {
struct cpu_timer_list *t = list_entry(timers->next,
struct cpu_timer_list,
entry);
if (cputime_lt(prof_ticks(tsk), t->expires.cpu)) {
tsk->it_prof_expires = t->expires.cpu;
break;
}
t->firing = 1;
list_move_tail(&t->entry, firing);
}
++timers;
tsk->it_virt_expires = cputime_zero;
while (!list_empty(timers)) {
struct cpu_timer_list *t = list_entry(timers->next,
struct cpu_timer_list,
entry);
if (cputime_lt(virt_ticks(tsk), t->expires.cpu)) {
tsk->it_virt_expires = t->expires.cpu;
break;
}
t->firing = 1;
list_move_tail(&t->entry, firing);
}
++timers;
tsk->it_sched_expires = 0;
while (!list_empty(timers)) {
struct cpu_timer_list *t = list_entry(timers->next,
struct cpu_timer_list,
entry);
if (tsk->sched_time < t->expires.sched) {
tsk->it_sched_expires = t->expires.sched;
break;
}
t->firing = 1;
list_move_tail(&t->entry, firing);
}
}
/*
* Check for any per-thread CPU timers that have fired and move them
* off the tsk->*_timers list onto the firing list. Per-thread timers
* have already been taken off.
*/
static void check_process_timers(struct task_struct *tsk,
struct list_head *firing)
{
struct signal_struct *const sig = tsk->signal;
cputime_t utime, stime, ptime, virt_expires, prof_expires;
unsigned long long sched_time, sched_expires;
struct task_struct *t;
struct list_head *timers = sig->cpu_timers;
/*
* Don't sample the current process CPU clocks if there are no timers.
*/
if (list_empty(&timers[CPUCLOCK_PROF]) &&
cputime_eq(sig->it_prof_expires, cputime_zero) &&
sig->rlim[RLIMIT_CPU].rlim_cur == RLIM_INFINITY &&
list_empty(&timers[CPUCLOCK_VIRT]) &&
cputime_eq(sig->it_virt_expires, cputime_zero) &&
list_empty(&timers[CPUCLOCK_SCHED]))
return;
/*
* Collect the current process totals.
*/
utime = sig->utime;
stime = sig->stime;
sched_time = sig->sched_time;
t = tsk;
do {
utime = cputime_add(utime, t->utime);
stime = cputime_add(stime, t->stime);
sched_time += t->sched_time;
t = next_thread(t);
} while (t != tsk);
ptime = cputime_add(utime, stime);
prof_expires = cputime_zero;
while (!list_empty(timers)) {
struct cpu_timer_list *t = list_entry(timers->next,
struct cpu_timer_list,
entry);
if (cputime_lt(ptime, t->expires.cpu)) {
prof_expires = t->expires.cpu;
break;
}
t->firing = 1;
list_move_tail(&t->entry, firing);
}
++timers;
virt_expires = cputime_zero;
while (!list_empty(timers)) {
struct cpu_timer_list *t = list_entry(timers->next,
struct cpu_timer_list,
entry);
if (cputime_lt(utime, t->expires.cpu)) {
virt_expires = t->expires.cpu;
break;
}
t->firing = 1;
list_move_tail(&t->entry, firing);
}
++timers;
sched_expires = 0;
while (!list_empty(timers)) {
struct cpu_timer_list *t = list_entry(timers->next,
struct cpu_timer_list,
entry);
if (sched_time < t->expires.sched) {
sched_expires = t->expires.sched;
break;
}
t->firing = 1;
list_move_tail(&t->entry, firing);
}
/*
* Check for the special case process timers.
*/
if (!cputime_eq(sig->it_prof_expires, cputime_zero)) {
if (cputime_ge(ptime, sig->it_prof_expires)) {
/* ITIMER_PROF fires and reloads. */
sig->it_prof_expires = sig->it_prof_incr;
if (!cputime_eq(sig->it_prof_expires, cputime_zero)) {
sig->it_prof_expires = cputime_add(
sig->it_prof_expires, ptime);
}
__group_send_sig_info(SIGPROF, SEND_SIG_PRIV, tsk);
}
if (!cputime_eq(sig->it_prof_expires, cputime_zero) &&
(cputime_eq(prof_expires, cputime_zero) ||
cputime_lt(sig->it_prof_expires, prof_expires))) {
prof_expires = sig->it_prof_expires;
}
}
if (!cputime_eq(sig->it_virt_expires, cputime_zero)) {
if (cputime_ge(utime, sig->it_virt_expires)) {
/* ITIMER_VIRTUAL fires and reloads. */
sig->it_virt_expires = sig->it_virt_incr;
if (!cputime_eq(sig->it_virt_expires, cputime_zero)) {
sig->it_virt_expires = cputime_add(
sig->it_virt_expires, utime);
}
__group_send_sig_info(SIGVTALRM, SEND_SIG_PRIV, tsk);
}
if (!cputime_eq(sig->it_virt_expires, cputime_zero) &&
(cputime_eq(virt_expires, cputime_zero) ||
cputime_lt(sig->it_virt_expires, virt_expires))) {
virt_expires = sig->it_virt_expires;
}
}
if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
unsigned long psecs = cputime_to_secs(ptime);
cputime_t x;
if (psecs >= sig->rlim[RLIMIT_CPU].rlim_max) {
/*
* At the hard limit, we just die.
* No need to calculate anything else now.
*/
__group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
return;
}
if (psecs >= sig->rlim[RLIMIT_CPU].rlim_cur) {
/*
* At the soft limit, send a SIGXCPU every second.
*/
__group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
if (sig->rlim[RLIMIT_CPU].rlim_cur
< sig->rlim[RLIMIT_CPU].rlim_max) {
sig->rlim[RLIMIT_CPU].rlim_cur++;
}
}
x = secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
if (cputime_eq(prof_expires, cputime_zero) ||
cputime_lt(x, prof_expires)) {
prof_expires = x;
}
}
if (!cputime_eq(prof_expires, cputime_zero) ||
!cputime_eq(virt_expires, cputime_zero) ||
sched_expires != 0) {
/*
* Rebalance the threads' expiry times for the remaining
* process CPU timers.
*/
cputime_t prof_left, virt_left, ticks;
unsigned long long sched_left, sched;
const unsigned int nthreads = atomic_read(&sig->live);
prof_left = cputime_sub(prof_expires, utime);
prof_left = cputime_sub(prof_left, stime);
prof_left = cputime_div(prof_left, nthreads);
virt_left = cputime_sub(virt_expires, utime);
virt_left = cputime_div(virt_left, nthreads);
if (sched_expires) {
sched_left = sched_expires - sched_time;
do_div(sched_left, nthreads);
} else {
sched_left = 0;
}
t = tsk;
do {
ticks = cputime_add(cputime_add(t->utime, t->stime),
prof_left);
if (!cputime_eq(prof_expires, cputime_zero) &&
(cputime_eq(t->it_prof_expires, cputime_zero) ||
cputime_gt(t->it_prof_expires, ticks))) {
t->it_prof_expires = ticks;
}
ticks = cputime_add(t->utime, virt_left);
if (!cputime_eq(virt_expires, cputime_zero) &&
(cputime_eq(t->it_virt_expires, cputime_zero) ||
cputime_gt(t->it_virt_expires, ticks))) {
t->it_virt_expires = ticks;
}
sched = t->sched_time + sched_left;
if (sched_expires && (t->it_sched_expires == 0 ||
t->it_sched_expires > sched)) {
t->it_sched_expires = sched;
}
do {
t = next_thread(t);
} while (unlikely(t->exit_state));
} while (t != tsk);
}
}
/*
* This is called from the signal code (via do_schedule_next_timer)
* when the last timer signal was delivered and we have to reload the timer.
*/
void posix_cpu_timer_schedule(struct k_itimer *timer)
{
struct task_struct *p = timer->it.cpu.task;
union cpu_time_count now;
if (unlikely(p == NULL))
/*
* The task was cleaned up already, no future firings.
*/
return;
/*
* Fetch the current sample and update the timer's expiry time.
*/
if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
cpu_clock_sample(timer->it_clock, p, &now);
bump_cpu_timer(timer, now);
if (unlikely(p->exit_state)) {
clear_dead_task(timer, now);
return;
}
read_lock(&tasklist_lock); /* arm_timer needs it. */
} else {
read_lock(&tasklist_lock);
if (unlikely(p->signal == NULL)) {
/*
* The process has been reaped.
* We can't even collect a sample any more.
*/
put_task_struct(p);
timer->it.cpu.task = p = NULL;
timer->it.cpu.expires.sched = 0;
read_unlock(&tasklist_lock);
return;
} else if (unlikely(p->exit_state) && thread_group_empty(p)) {
/*
* We've noticed that the thread is dead, but
* not yet reaped. Take this opportunity to
* drop our task ref.
*/
clear_dead_task(timer, now);
read_unlock(&tasklist_lock);
return;
}
cpu_clock_sample_group(timer->it_clock, p, &now);
bump_cpu_timer(timer, now);
/* Leave the tasklist_lock locked for the call below. */
}
/*
* Now re-arm for the new expiry time.
*/
arm_timer(timer, now);
read_unlock(&tasklist_lock);
}
/*
* This is called from the timer interrupt handler. The irq handler has
* already updated our counts. We need to check if any timers fire now.
* Interrupts are disabled.
*/
void run_posix_cpu_timers(struct task_struct *tsk)
{
LIST_HEAD(firing);
struct k_itimer *timer, *next;
BUG_ON(!irqs_disabled());
#define UNEXPIRED(clock) \
(cputime_eq(tsk->it_##clock##_expires, cputime_zero) || \
cputime_lt(clock##_ticks(tsk), tsk->it_##clock##_expires))
if (UNEXPIRED(prof) && UNEXPIRED(virt) &&
(tsk->it_sched_expires == 0 ||
tsk->sched_time < tsk->it_sched_expires))
return;
#undef UNEXPIRED
BUG_ON(tsk->exit_state);
/*
* Double-check with locks held.
*/
read_lock(&tasklist_lock);
spin_lock(&tsk->sighand->siglock);
/*
* Here we take off tsk->cpu_timers[N] and tsk->signal->cpu_timers[N]
* all the timers that are firing, and put them on the firing list.
*/
check_thread_timers(tsk, &firing);
check_process_timers(tsk, &firing);
/*
* We must release these locks before taking any timer's lock.
* There is a potential race with timer deletion here, as the
* siglock now protects our private firing list. We have set
* the firing flag in each timer, so that a deletion attempt
* that gets the timer lock before we do will give it up and
* spin until we've taken care of that timer below.
*/
spin_unlock(&tsk->sighand->siglock);
read_unlock(&tasklist_lock);
/*
* Now that all the timers on our list have the firing flag,
* noone will touch their list entries but us. We'll take
* each timer's lock before clearing its firing flag, so no
* timer call will interfere.
*/
list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
int firing;
spin_lock(&timer->it_lock);
list_del_init(&timer->it.cpu.entry);
firing = timer->it.cpu.firing;
timer->it.cpu.firing = 0;
/*
* The firing flag is -1 if we collided with a reset
* of the timer, which already reported this
* almost-firing as an overrun. So don't generate an event.
*/
if (likely(firing >= 0)) {
cpu_timer_fire(timer);
}
spin_unlock(&timer->it_lock);
}
}
/*
* Set one of the process-wide special case CPU timers.
* The tasklist_lock and tsk->sighand->siglock must be held by the caller.
* The oldval argument is null for the RLIMIT_CPU timer, where *newval is
* absolute; non-null for ITIMER_*, where *newval is relative and we update
* it to be absolute, *oldval is absolute and we update it to be relative.
*/
void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
cputime_t *newval, cputime_t *oldval)
{
union cpu_time_count now;
struct list_head *head;
BUG_ON(clock_idx == CPUCLOCK_SCHED);
cpu_clock_sample_group_locked(clock_idx, tsk, &now);
if (oldval) {
if (!cputime_eq(*oldval, cputime_zero)) {
if (cputime_le(*oldval, now.cpu)) {
/* Just about to fire. */
*oldval = jiffies_to_cputime(1);
} else {
*oldval = cputime_sub(*oldval, now.cpu);
}
}
if (cputime_eq(*newval, cputime_zero))
return;
*newval = cputime_add(*newval, now.cpu);
/*
* If the RLIMIT_CPU timer will expire before the
* ITIMER_PROF timer, we have nothing else to do.
*/
if (tsk->signal->rlim[RLIMIT_CPU].rlim_cur
< cputime_to_secs(*newval))
return;
}
/*
* Check whether there are any process timers already set to fire
* before this one. If so, we don't have anything more to do.
*/
head = &tsk->signal->cpu_timers[clock_idx];
if (list_empty(head) ||
cputime_ge(list_entry(head->next,
struct cpu_timer_list, entry)->expires.cpu,
*newval)) {
/*
* Rejigger each thread's expiry time so that one will
* notice before we hit the process-cumulative expiry time.
*/
union cpu_time_count expires = { .sched = 0 };
expires.cpu = *newval;
process_timer_rebalance(tsk, clock_idx, expires, now);
}
}
static long posix_cpu_clock_nanosleep_restart(struct restart_block *);
int posix_cpu_nsleep(clockid_t which_clock, int flags,
struct timespec *rqtp)
{
struct restart_block *restart_block =
¤t_thread_info()->restart_block;
struct k_itimer timer;
int error;
/*
* Diagnose required errors first.
*/
if (CPUCLOCK_PERTHREAD(which_clock) &&
(CPUCLOCK_PID(which_clock) == 0 ||
CPUCLOCK_PID(which_clock) == current->pid))
return -EINVAL;
/*
* Set up a temporary timer and then wait for it to go off.
*/
memset(&timer, 0, sizeof timer);
spin_lock_init(&timer.it_lock);
timer.it_clock = which_clock;
timer.it_overrun = -1;
error = posix_cpu_timer_create(&timer);
timer.it_process = current;
if (!error) {
struct timespec __user *rmtp;
static struct itimerspec zero_it;
struct itimerspec it = { .it_value = *rqtp,
.it_interval = {} };
spin_lock_irq(&timer.it_lock);
error = posix_cpu_timer_set(&timer, flags, &it, NULL);
if (error) {
spin_unlock_irq(&timer.it_lock);
return error;
}
while (!signal_pending(current)) {
if (timer.it.cpu.expires.sched == 0) {
/*
* Our timer fired and was reset.
*/
spin_unlock_irq(&timer.it_lock);
return 0;
}
/*
* Block until cpu_timer_fire (or a signal) wakes us.
*/
__set_current_state(TASK_INTERRUPTIBLE);
spin_unlock_irq(&timer.it_lock);
schedule();
spin_lock_irq(&timer.it_lock);
}
/*
* We were interrupted by a signal.
*/
sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp);
posix_cpu_timer_set(&timer, 0, &zero_it, &it);
spin_unlock_irq(&timer.it_lock);
if ((it.it_value.tv_sec | it.it_value.tv_nsec) == 0) {
/*
* It actually did fire already.
*/
return 0;
}
/*
* Report back to the user the time still remaining.
*/
rmtp = (struct timespec __user *) restart_block->arg1;
if (rmtp != NULL && !(flags & TIMER_ABSTIME) &&
copy_to_user(rmtp, &it.it_value, sizeof *rmtp))
return -EFAULT;
restart_block->fn = posix_cpu_clock_nanosleep_restart;
/* Caller already set restart_block->arg1 */
restart_block->arg0 = which_clock;
restart_block->arg2 = rqtp->tv_sec;
restart_block->arg3 = rqtp->tv_nsec;
error = -ERESTART_RESTARTBLOCK;
}
return error;
}
static long
posix_cpu_clock_nanosleep_restart(struct restart_block *restart_block)
{
clockid_t which_clock = restart_block->arg0;
struct timespec t = { .tv_sec = restart_block->arg2,
.tv_nsec = restart_block->arg3 };
restart_block->fn = do_no_restart_syscall;
return posix_cpu_nsleep(which_clock, TIMER_ABSTIME, &t);
}
#define PROCESS_CLOCK MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
#define THREAD_CLOCK MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
static int process_cpu_clock_getres(clockid_t which_clock, struct timespec *tp)
{
return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
}
static int process_cpu_clock_get(clockid_t which_clock, struct timespec *tp)
{
return posix_cpu_clock_get(PROCESS_CLOCK, tp);
}
static int process_cpu_timer_create(struct k_itimer *timer)
{
timer->it_clock = PROCESS_CLOCK;
return posix_cpu_timer_create(timer);
}
static int process_cpu_nsleep(clockid_t which_clock, int flags,
struct timespec *rqtp)
{
return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp);
}
static int thread_cpu_clock_getres(clockid_t which_clock, struct timespec *tp)
{
return posix_cpu_clock_getres(THREAD_CLOCK, tp);
}
static int thread_cpu_clock_get(clockid_t which_clock, struct timespec *tp)
{
return posix_cpu_clock_get(THREAD_CLOCK, tp);
}
static int thread_cpu_timer_create(struct k_itimer *timer)
{
timer->it_clock = THREAD_CLOCK;
return posix_cpu_timer_create(timer);
}
static int thread_cpu_nsleep(clockid_t which_clock, int flags,
struct timespec *rqtp)
{
return -EINVAL;
}
static __init int init_posix_cpu_timers(void)
{
struct k_clock process = {
.clock_getres = process_cpu_clock_getres,
.clock_get = process_cpu_clock_get,
.clock_set = do_posix_clock_nosettime,
.timer_create = process_cpu_timer_create,
.nsleep = process_cpu_nsleep,
};
struct k_clock thread = {
.clock_getres = thread_cpu_clock_getres,
.clock_get = thread_cpu_clock_get,
.clock_set = do_posix_clock_nosettime,
.timer_create = thread_cpu_timer_create,
.nsleep = thread_cpu_nsleep,
};
register_posix_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
register_posix_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
return 0;
}
__initcall(init_posix_cpu_timers);
