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- #include "sched.h"
- #include <linux/proc_fs.h>
- #include <linux/seq_file.h>
- #include <linux/kallsyms.h>
- #include <linux/utsname.h>
- #include <linux/security.h>
- #include <linux/export.h>
- unsigned int __read_mostly sysctl_sched_autogroup_enabled = 1;
- static struct autogroup autogroup_default;
- static atomic_t autogroup_seq_nr;
- 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;
- }
- 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_offline_group(ag->tg);
- 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;
- }
- 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.
- */
- 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;
- sched_online_group(tg, &root_task_group);
- 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);
- }
- bool task_wants_autogroup(struct task_struct *p, struct task_group *tg)
- {
- if (tg != &root_task_group)
- return false;
- /*
- * If we race with autogroup_move_group() the caller can use the old
- * value of signal->autogroup but in this case sched_move_task() will
- * be called again before autogroup_kref_put().
- */
- return true;
- }
- 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.
- */
- 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 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 < MIN_NICE || nice > MAX_NICE)
- 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
- 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 */
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