#ifdef CONFIG_SCHEDSTATS

/*
 * Expects runqueue lock to be held for atomicity of update
 */
static inline void
rq_sched_info_arrive(struct rq *rq, unsigned long long delta)
{
        if (rq) {
                rq->rq_sched_info.run_delay += delta;
                rq->rq_sched_info.pcount++;
        }
}

/*
 * Expects runqueue lock to be held for atomicity of update
 */
static inline void
rq_sched_info_depart(struct rq *rq, unsigned long long delta)
{
        if (rq)
                rq->rq_cpu_time += delta;
}

static inline void
rq_sched_info_dequeued(struct rq *rq, unsigned long long delta)
{
        if (rq)
                rq->rq_sched_info.run_delay += delta;
}
# define schedstat_inc(rq, field)       do { (rq)->field++; } while (0)
# define schedstat_add(rq, field, amt)  do { (rq)->field += (amt); } while (0)
# define schedstat_set(var, val)        do { var = (val); } while (0)
#else /* !CONFIG_SCHEDSTATS */
static inline void
rq_sched_info_arrive(struct rq *rq, unsigned long long delta)
{}
static inline void
rq_sched_info_dequeued(struct rq *rq, unsigned long long delta)
{}
static inline void
rq_sched_info_depart(struct rq *rq, unsigned long long delta)
{}
# define schedstat_inc(rq, field)       do { } while (0)
# define schedstat_add(rq, field, amt)  do { } while (0)
# define schedstat_set(var, val)        do { } while (0)
#endif

#if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT)
static inline void sched_info_reset_dequeued(struct task_struct *t)
{
        t->sched_info.last_queued = 0;
}

/*
 * We are interested in knowing how long it was from the *first* time a
 * task was queued to the time that it finally hit a cpu, we call this routine
 * from dequeue_task() to account for possible rq->clock skew across cpus. The
 * delta taken on each cpu would annul the skew.
 */
static inline void sched_info_dequeued(struct task_struct *t)
{
        unsigned long long now = rq_clock(task_rq(t)), delta = 0;

        if (unlikely(sched_info_on()))
                if (t->sched_info.last_queued)
                        delta = now - t->sched_info.last_queued;
        sched_info_reset_dequeued(t);
        t->sched_info.run_delay += delta;

        rq_sched_info_dequeued(task_rq(t), delta);
}

/*
 * Called when a task finally hits the cpu.  We can now calculate how
 * long it was waiting to run.  We also note when it began so that we
 * can keep stats on how long its timeslice is.
 */
static void sched_info_arrive(struct task_struct *t)
{
        unsigned long long now = rq_clock(task_rq(t)), delta = 0;

        if (t->sched_info.last_queued)
                delta = now - t->sched_info.last_queued;
        sched_info_reset_dequeued(t);
        t->sched_info.run_delay += delta;
        t->sched_info.last_arrival = now;
        t->sched_info.pcount++;

        rq_sched_info_arrive(task_rq(t), delta);
}

/*
 * This function is only called from enqueue_task(), but also only updates
 * the timestamp if it is already not set.  It's assumed that
 * sched_info_dequeued() will clear that stamp when appropriate.
 */
static inline void sched_info_queued(struct task_struct *t)
{
        if (unlikely(sched_info_on()))
                if (!t->sched_info.last_queued)
                        t->sched_info.last_queued = rq_clock(task_rq(t));
}

/*
 * Called when a process ceases being the active-running process involuntarily
 * due, typically, to expiring its time slice (this may also be called when
 * switching to the idle task).  Now we can calculate how long we ran.
 * Also, if the process is still in the TASK_RUNNING state, call
 * sched_info_queued() to mark that it has now again started waiting on
 * the runqueue.
 */
static inline void sched_info_depart(struct task_struct *t)
{
        unsigned long long delta = rq_clock(task_rq(t)) -
                                        t->sched_info.last_arrival;

        rq_sched_info_depart(task_rq(t), delta);

        if (t->state == TASK_RUNNING)
                sched_info_queued(t);
}

/*
 * Called when tasks are switched involuntarily due, typically, to expiring
 * their time slice.  (This may also be called when switching to or from
 * the idle task.)  We are only called when prev != next.
 */
static inline void
__sched_info_switch(struct task_struct *prev, struct task_struct *next)
{
        struct rq *rq = task_rq(prev);

        /*
         * prev now departs the cpu.  It's not interesting to record
         * stats about how efficient we were at scheduling the idle
         * process, however.
         */
        if (prev != rq->idle)
                sched_info_depart(prev);

        if (next != rq->idle)
                sched_info_arrive(next);
}
static inline void
sched_info_switch(struct task_struct *prev, struct task_struct *next)
{
        if (unlikely(sched_info_on()))
                __sched_info_switch(prev, next);
}
#else
#define sched_info_queued(t)                    do { } while (0)
#define sched_info_reset_dequeued(t)    do { } while (0)
#define sched_info_dequeued(t)                  do { } while (0)
#define sched_info_switch(t, next)              do { } while (0)
#endif /* CONFIG_SCHEDSTATS || CONFIG_TASK_DELAY_ACCT */

/*
 * The following are functions that support scheduler-internal time accounting.
 * These functions are generally called at the timer tick.  None of this depends
 * on CONFIG_SCHEDSTATS.
 */

/**
 * cputimer_running - return true if cputimer is running
 *
 * @tsk:        Pointer to target task.
 */
static inline bool cputimer_running(struct task_struct *tsk)

{
        struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;

        if (!cputimer->running)
                return false;

        /*
         * After we flush the task's sum_exec_runtime to sig->sum_sched_runtime
         * in __exit_signal(), we won't account to the signal struct further
         * cputime consumed by that task, even though the task can still be
         * ticking after __exit_signal().
         *
         * In order to keep a consistent behaviour between thread group cputime
         * and thread group cputimer accounting, lets also ignore the cputime
         * elapsing after __exit_signal() in any thread group timer running.
         *
         * This makes sure that POSIX CPU clocks and timers are synchronized, so
         * that a POSIX CPU timer won't expire while the corresponding POSIX CPU
         * clock delta is behind the expiring timer value.
         */
        if (unlikely(!tsk->sighand))
                return false;

        return true;
}

/**
 * account_group_user_time - Maintain utime for a thread group.
 *
 * @tsk:        Pointer to task structure.
 * @cputime:    Time value by which to increment the utime field of the
 *              thread_group_cputime structure.
 *
 * If thread group time is being maintained, get the structure for the
 * running CPU and update the utime field there.
 */
static inline void account_group_user_time(struct task_struct *tsk,
                                           cputime_t cputime)
{
        struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;

        if (!cputimer_running(tsk))
                return;

        raw_spin_lock(&cputimer->lock);
        cputimer->cputime.utime += cputime;
        raw_spin_unlock(&cputimer->lock);
}

/**
 * account_group_system_time - Maintain stime for a thread group.
 *
 * @tsk:        Pointer to task structure.
 * @cputime:    Time value by which to increment the stime field of the
 *              thread_group_cputime structure.
 *
 * If thread group time is being maintained, get the structure for the
 * running CPU and update the stime field there.
 */
static inline void account_group_system_time(struct task_struct *tsk,
                                             cputime_t cputime)
{
        struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;

        if (!cputimer_running(tsk))
                return;

        raw_spin_lock(&cputimer->lock);
        cputimer->cputime.stime += cputime;
        raw_spin_unlock(&cputimer->lock);
}

/**
 * account_group_exec_runtime - Maintain exec runtime for a thread group.
 *
 * @tsk:        Pointer to task structure.
 * @ns:         Time value by which to increment the sum_exec_runtime field
 *              of the thread_group_cputime structure.
 *
 * If thread group time is being maintained, get the structure for the
 * running CPU and update the sum_exec_runtime field there.
 */
static inline void account_group_exec_runtime(struct task_struct *tsk,
                                              unsigned long long ns)
{
        struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;

        if (!cputimer_running(tsk))
                return;

        raw_spin_lock(&cputimer->lock);
        cputimer->cputime.sum_exec_runtime += ns;
        raw_spin_unlock(&cputimer->lock);
}