#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 */