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#ifdef CONFIG_SCHED_AUTOGROUP
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/kallsyms.h>
#include <linux/utsname.h>
unsigned int __read_mostly sysctl_sched_autogroup_enabled = 1;
static struct autogroup autogroup_default;
static atomic_t autogroup_seq_nr;
static void __init autogroup_init(struct task_struct *init_task)
{
autogroup_default.tg = &root_task_group;
kref_init(&autogroup_default.kref);
init_rwsem(&autogroup_default.lock);
init_task->signal->autogroup = &autogroup_default;
}
static inline void autogroup_free(struct task_group *tg)
{
kfree(tg->autogroup);
}
static inline void autogroup_destroy(struct kref *kref)
{
struct autogroup *ag = container_of(kref, struct autogroup, kref);
#ifdef CONFIG_RT_GROUP_SCHED
/* We've redirected RT tasks to the root task group... */
ag->tg->rt_se = NULL;
ag->tg->rt_rq = NULL;
#endif
sched_destroy_group(ag->tg);
}
static inline void autogroup_kref_put(struct autogroup *ag)
{
kref_put(&ag->kref, autogroup_destroy);
}
static inline struct autogroup *autogroup_kref_get(struct autogroup *ag)
{
kref_get(&ag->kref);
return ag;
}
static inline struct autogroup *autogroup_task_get(struct task_struct *p)
{
struct autogroup *ag;
unsigned long flags;
if (!lock_task_sighand(p, &flags))
return autogroup_kref_get(&autogroup_default);
ag = autogroup_kref_get(p->signal->autogroup);
unlock_task_sighand(p, &flags);
return ag;
}
#ifdef CONFIG_RT_GROUP_SCHED
static void free_rt_sched_group(struct task_group *tg);
#endif
static inline struct autogroup *autogroup_create(void)
{
struct autogroup *ag = kzalloc(sizeof(*ag), GFP_KERNEL);
struct task_group *tg;
if (!ag)
goto out_fail;
tg = sched_create_group(&root_task_group);
if (IS_ERR(tg))
goto out_free;
kref_init(&ag->kref);
init_rwsem(&ag->lock);
ag->id = atomic_inc_return(&autogroup_seq_nr);
ag->tg = tg;
#ifdef CONFIG_RT_GROUP_SCHED
/*
* Autogroup RT tasks are redirected to the root task group
* so we don't have to move tasks around upon policy change,
* or flail around trying to allocate bandwidth on the fly.
* A bandwidth exception in __sched_setscheduler() allows
* the policy change to proceed. Thereafter, task_group()
* returns &root_task_group, so zero bandwidth is required.
*/
free_rt_sched_group(tg);
tg->rt_se = root_task_group.rt_se;
tg->rt_rq = root_task_group.rt_rq;
#endif
tg->autogroup = ag;
return ag;
out_free:
kfree(ag);
out_fail:
if (printk_ratelimit()) {
printk(KERN_WARNING "autogroup_create: %s failure.\n",
ag ? "sched_create_group()" : "kmalloc()");
}
return autogroup_kref_get(&autogroup_default);
}
static inline bool
task_wants_autogroup(struct task_struct *p, struct task_group *tg)
{
if (tg != &root_task_group)
return false;
if (p->sched_class != &fair_sched_class)
return false;
/*
* We can only assume the task group can't go away on us if
* autogroup_move_group() can see us on ->thread_group list.
*/
if (p->flags & PF_EXITING)
return false;
return true;
}
static inline bool task_group_is_autogroup(struct task_group *tg)
{
return !!tg->autogroup;
}
static inline struct task_group *
autogroup_task_group(struct task_struct *p, struct task_group *tg)
{
int enabled = ACCESS_ONCE(sysctl_sched_autogroup_enabled);
if (enabled && task_wants_autogroup(p, tg))
return p->signal->autogroup->tg;
return tg;
}
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);
}
/* 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 reference added by autogroup_create() */
autogroup_kref_put(ag);
}
EXPORT_SYMBOL(sched_autogroup_create_attach);
/* Cannot be called under siglock. Currently has no users */
void sched_autogroup_detach(struct task_struct *p)
{
autogroup_move_group(p, &autogroup_default);
}
EXPORT_SYMBOL(sched_autogroup_detach);
void sched_autogroup_fork(struct signal_struct *sig)
{
sig->autogroup = autogroup_task_get(current);
}
void sched_autogroup_exit(struct signal_struct *sig)
{
autogroup_kref_put(sig->autogroup);
}
static int __init setup_autogroup(char *str)
{
sysctl_sched_autogroup_enabled = 0;
return 1;
}
__setup("noautogroup", setup_autogroup);
#ifdef CONFIG_PROC_FS
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;
}
void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m)
{
struct autogroup *ag = autogroup_task_get(p);
if (!task_group_is_autogroup(ag->tg))
goto out;
down_read(&ag->lock);
seq_printf(m, "/autogroup-%ld nice %d\n", ag->id, ag->nice);
up_read(&ag->lock);
out:
autogroup_kref_put(ag);
}
#endif /* CONFIG_PROC_FS */
#ifdef CONFIG_SCHED_DEBUG
static inline int autogroup_path(struct task_group *tg, char *buf, int buflen)
{
if (!task_group_is_autogroup(tg))
return 0;
return snprintf(buf, buflen, "%s-%ld", "/autogroup", tg->autogroup->id);
}
#endif /* CONFIG_SCHED_DEBUG */
#endif /* CONFIG_SCHED_AUTOGROUP */
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