static void
autogroup_move_group(struct task_struct *p, struct autogroup *ag)
{
struct autogroup *prev;
struct task_struct *t;
unsigned long flags;
BUG_ON(!lock_task_sighand(p, &flags));
prev = p->signal->autogroup;
if (prev == ag) {
unlock_task_sighand(p, &flags);
return;
}
p->signal->autogroup = autogroup_kref_get(ag);
if (!ACCESS_ONCE(sysctl_sched_autogroup_enabled))
goto out;
t = p;
do {
sched_move_task(t);
} while_each_thread(p, t);
out:
unlock_task_sighand(p, &flags);
autogroup_kref_put(prev);
}
int proc_sched_autogroup_set_nice(struct task_struct *p, int *nice)
{
static unsigned long next = INITIAL_JIFFIES;
struct autogroup *ag;
int err;
if (*nice < -20 || *nice > 19)
return -EINVAL;
err = security_task_setnice(current, *nice);
if (err)
return err;
if (*nice < 0 && !can_nice(current, *nice))
return -EPERM;
/* this is a heavy operation taking global locks.. */
if (!capable(CAP_SYS_ADMIN) && time_before(jiffies, next))
return -EAGAIN;
next = HZ / 10 + jiffies;
ag = autogroup_task_get(p);
down_write(&ag->lock);
err = sched_group_set_shares(ag->tg, prio_to_weight[*nice + 20]);
if (!err)
ag->nice = *nice;
up_write(&ag->lock);
autogroup_kref_put(ag);
return err;
}
static void
autogroup_move_group(struct task_struct *p, struct autogroup *ag)
{
struct autogroup *prev;
struct task_struct *t;
unsigned long flags;
BUG_ON(!lock_task_sighand(p, &flags));
prev = p->signal->autogroup;
if (prev == ag) {
unlock_task_sighand(p, &flags);
return;
}
p->signal->autogroup = autogroup_kref_get(ag);
/*
* We can't avoid sched_move_task() after we changed signal->autogroup,
* this process can already run with task_group() == prev->tg or we can
* race with cgroup code which can read autogroup = prev under rq->lock.
* In the latter case for_each_thread() can not miss a migrating thread,
* cpu_cgroup_attach() must not be possible after cgroup_exit() and it
* can't be removed from thread list, we hold ->siglock.
*
* If an exiting thread was already removed from thread list we rely on
* sched_autogroup_exit_task().
*/
for_each_thread(p, t)
sched_move_task(t);
unlock_task_sighand(p, &flags);
autogroup_kref_put(prev);
}
/* Allocates GFP_KERNEL, cannot be called under any spinlock */
void sched_autogroup_create_attach(struct task_struct *p)
{
struct autogroup *ag = autogroup_create();
autogroup_move_group(p, ag);
/* drop extra refrence added by autogroup_create() */
autogroup_kref_put(ag);
}
void sched_autogroup_create_attach(struct task_struct *p)
{
struct autogroup *ag = autogroup_create();
autogroup_move_group(p, ag);
autogroup_kref_put(ag);
}
void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m)
{
struct autogroup *ag = autogroup_task_get(p);
down_read(&ag->lock);
seq_printf(m, "/autogroup-%ld nice %d\n", ag->id, ag->nice);
up_read(&ag->lock);
autogroup_kref_put(ag);
}
void sched_autogroup_exit(struct signal_struct *sig)
{
autogroup_kref_put(sig->autogroup);
}