path: root/kernel/posix-cpu-timers.c

/*
 * Implement CPU time clocks for the POSIX clock interface.
 */

#include <linux/sched.h>
#include <linux/posix-timers.h>
#include <linux/errno.h>
#include <linux/math64.h>
#include <asm/uaccess.h>

#ifdef CONFIG_SMP
/*
 * Allocate the thread_group_cputime structure appropriately for SMP kernels
 * and fill in the current values of the fields.  Called from copy_signal()
 * via thread_group_cputime_clone_thread() when adding a second or subsequent
 * thread to a thread group.  Assumes interrupts are enabled when called.
 */
int thread_group_cputime_alloc_smp(struct task_struct *tsk)
{
	struct signal_struct *sig = tsk->signal;
	struct task_cputime *cputime;

	/*
	 * If we have multiple threads and we don't already have a
	 * per-CPU task_cputime struct, allocate one and fill it in with
	 * the times accumulated so far.
	 */
	if (sig->cputime.totals)
		return 0;
	cputime = alloc_percpu(struct task_cputime);
	if (cputime == NULL)
		return -ENOMEM;
	read_lock(&tasklist_lock);
	spin_lock_irq(&tsk->sighand->siglock);
	if (sig->cputime.totals) {
		spin_unlock_irq(&tsk->sighand->siglock);
		read_unlock(&tasklist_lock);
		free_percpu(cputime);
		return 0;
	}
	sig->cputime.totals = cputime;
	cputime = per_cpu_ptr(sig->cputime.totals, get_cpu());
	cputime->utime = tsk->utime;
	cputime->stime = tsk->stime;
	cputime->sum_exec_runtime = tsk->se.sum_exec_runtime;
	put_cpu_no_resched();
	spin_unlock_irq(&tsk->sighand->siglock);
	read_unlock(&tasklist_lock);
	return 0;
}

/**
 * thread_group_cputime_smp - Sum the