1 #ifdef CONFIG_SCHED_AUTOGROUP
5 #include <linux/proc_fs.h>
6 #include <linux/seq_file.h>
7 #include <linux/kallsyms.h>
8 #include <linux/utsname.h>
9 #include <linux/security.h>
10 #include <linux/export.h>
12 unsigned int __read_mostly sysctl_sched_autogroup_enabled = 1;
13 static struct autogroup autogroup_default;
14 static atomic_t autogroup_seq_nr;
16 void __init autogroup_init(struct task_struct *init_task)
18 autogroup_default.tg = &root_task_group;
19 kref_init(&autogroup_default.kref);
20 init_rwsem(&autogroup_default.lock);
21 init_task->signal->autogroup = &autogroup_default;
24 void autogroup_free(struct task_group *tg)
29 static inline void autogroup_destroy(struct kref *kref)
31 struct autogroup *ag = container_of(kref, struct autogroup, kref);
33 #ifdef CONFIG_RT_GROUP_SCHED
34 /* We've redirected RT tasks to the root task group... */
38 sched_offline_group(ag->tg);
39 sched_destroy_group(ag->tg);
42 static inline void autogroup_kref_put(struct autogroup *ag)
44 kref_put(&ag->kref, autogroup_destroy);
47 static inline struct autogroup *autogroup_kref_get(struct autogroup *ag)
53 static inline struct autogroup *autogroup_task_get(struct task_struct *p)
58 if (!lock_task_sighand(p, &flags))
59 return autogroup_kref_get(&autogroup_default);
61 ag = autogroup_kref_get(p->signal->autogroup);
62 unlock_task_sighand(p, &flags);
67 static inline struct autogroup *autogroup_create(void)
69 struct autogroup *ag = kzalloc(sizeof(*ag), GFP_KERNEL);
70 struct task_group *tg;
75 tg = sched_create_group(&root_task_group);
81 init_rwsem(&ag->lock);
82 ag->id = atomic_inc_return(&autogroup_seq_nr);
84 #ifdef CONFIG_RT_GROUP_SCHED
86 * Autogroup RT tasks are redirected to the root task group
87 * so we don't have to move tasks around upon policy change,
88 * or flail around trying to allocate bandwidth on the fly.
89 * A bandwidth exception in __sched_setscheduler() allows
90 * the policy change to proceed. Thereafter, task_group()
91 * returns &root_task_group, so zero bandwidth is required.
93 free_rt_sched_group(tg);
94 tg->rt_se = root_task_group.rt_se;
95 tg->rt_rq = root_task_group.rt_rq;
99 sched_online_group(tg, &root_task_group);
105 if (printk_ratelimit()) {
106 printk(KERN_WARNING "autogroup_create: %s failure.\n",
107 ag ? "sched_create_group()" : "kmalloc()");
110 return autogroup_kref_get(&autogroup_default);
113 bool task_wants_autogroup(struct task_struct *p, struct task_group *tg)
115 if (tg != &root_task_group)
118 if (p->sched_class != &fair_sched_class)
122 * We can only assume the task group can't go away on us if
123 * autogroup_move_group() can see us on ->thread_group list.
125 if (p->flags & PF_EXITING)
132 autogroup_move_group(struct task_struct *p, struct autogroup *ag)
134 struct autogroup *prev;
135 struct task_struct *t;
138 BUG_ON(!lock_task_sighand(p, &flags));
140 prev = p->signal->autogroup;
142 unlock_task_sighand(p, &flags);
146 p->signal->autogroup = autogroup_kref_get(ag);
148 if (!ACCESS_ONCE(sysctl_sched_autogroup_enabled))
151 for_each_thread(p, t)
154 unlock_task_sighand(p, &flags);
155 autogroup_kref_put(prev);
158 /* Allocates GFP_KERNEL, cannot be called under any spinlock */
159 void sched_autogroup_create_attach(struct task_struct *p)
161 struct autogroup *ag = autogroup_create();
163 autogroup_move_group(p, ag);
164 /* drop extra reference added by autogroup_create() */
165 autogroup_kref_put(ag);
167 EXPORT_SYMBOL(sched_autogroup_create_attach);
169 /* Cannot be called under siglock. Currently has no users */
170 void sched_autogroup_detach(struct task_struct *p)
172 autogroup_move_group(p, &autogroup_default);
174 EXPORT_SYMBOL(sched_autogroup_detach);
176 void sched_autogroup_fork(struct signal_struct *sig)
178 sig->autogroup = autogroup_task_get(current);
181 void sched_autogroup_exit(struct signal_struct *sig)
183 autogroup_kref_put(sig->autogroup);
186 static int __init setup_autogroup(char *str)
188 sysctl_sched_autogroup_enabled = 0;
193 __setup("noautogroup", setup_autogroup);
195 #ifdef CONFIG_PROC_FS
197 int proc_sched_autogroup_set_nice(struct task_struct *p, int nice)
199 static unsigned long next = INITIAL_JIFFIES;
200 struct autogroup *ag;
203 if (nice < MIN_NICE || nice > MAX_NICE)
206 err = security_task_setnice(current, nice);
210 if (nice < 0 && !can_nice(current, nice))
213 /* this is a heavy operation taking global locks.. */
214 if (!capable(CAP_SYS_ADMIN) && time_before(jiffies, next))
217 next = HZ / 10 + jiffies;
218 ag = autogroup_task_get(p);
220 down_write(&ag->lock);
221 err = sched_group_set_shares(ag->tg, prio_to_weight[nice + 20]);
226 autogroup_kref_put(ag);
231 void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m)
233 struct autogroup *ag = autogroup_task_get(p);
235 if (!task_group_is_autogroup(ag->tg))
238 down_read(&ag->lock);
239 seq_printf(m, "/autogroup-%ld nice %d\n", ag->id, ag->nice);
243 autogroup_kref_put(ag);
245 #endif /* CONFIG_PROC_FS */
247 #ifdef CONFIG_SCHED_DEBUG
248 int autogroup_path(struct task_group *tg, char *buf, int buflen)
250 if (!task_group_is_autogroup(tg))
253 return snprintf(buf, buflen, "%s-%ld", "/autogroup", tg->autogroup->id);
255 #endif /* CONFIG_SCHED_DEBUG */
257 #endif /* CONFIG_SCHED_AUTOGROUP */