1 #ifdef CONFIG_SCHED_AUTOGROUP
3 #include <linux/proc_fs.h>
4 #include <linux/seq_file.h>
5 #include <linux/kallsyms.h>
6 #include <linux/utsname.h>
8 unsigned int __read_mostly sysctl_sched_autogroup_enabled = 1;
9 static struct autogroup autogroup_default;
10 static atomic_t autogroup_seq_nr;
12 static void __init autogroup_init(struct task_struct *init_task)
14 autogroup_default.tg = &root_task_group;
15 root_task_group.autogroup = &autogroup_default;
16 kref_init(&autogroup_default.kref);
17 init_rwsem(&autogroup_default.lock);
18 init_task->signal->autogroup = &autogroup_default;
21 static inline void autogroup_free(struct task_group *tg)
26 static inline void autogroup_destroy(struct kref *kref)
28 struct autogroup *ag = container_of(kref, struct autogroup, kref);
30 #ifdef CONFIG_RT_GROUP_SCHED
31 /* We've redirected RT tasks to the root task group... */
35 sched_destroy_group(ag->tg);
38 static inline void autogroup_kref_put(struct autogroup *ag)
40 kref_put(&ag->kref, autogroup_destroy);
43 static inline struct autogroup *autogroup_kref_get(struct autogroup *ag)
49 static inline struct autogroup *autogroup_task_get(struct task_struct *p)
54 if (!lock_task_sighand(p, &flags))
55 return autogroup_kref_get(&autogroup_default);
57 ag = autogroup_kref_get(p->signal->autogroup);
58 unlock_task_sighand(p, &flags);
63 #ifdef CONFIG_RT_GROUP_SCHED
64 static void free_rt_sched_group(struct task_group *tg);
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;
104 if (printk_ratelimit()) {
105 printk(KERN_WARNING "autogroup_create: %s failure.\n",
106 ag ? "sched_create_group()" : "kmalloc()");
109 return autogroup_kref_get(&autogroup_default);
113 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)
131 static inline bool task_group_is_autogroup(struct task_group *tg)
133 return tg != &root_task_group && tg->autogroup;
136 static inline struct task_group *
137 autogroup_task_group(struct task_struct *p, struct task_group *tg)
139 int enabled = ACCESS_ONCE(sysctl_sched_autogroup_enabled);
141 if (enabled && task_wants_autogroup(p, tg))
142 return p->signal->autogroup->tg;
148 autogroup_move_group(struct task_struct *p, struct autogroup *ag)
150 struct autogroup *prev;
151 struct task_struct *t;
154 BUG_ON(!lock_task_sighand(p, &flags));
156 prev = p->signal->autogroup;
158 unlock_task_sighand(p, &flags);
162 p->signal->autogroup = autogroup_kref_get(ag);
164 if (!ACCESS_ONCE(sysctl_sched_autogroup_enabled))
170 } while_each_thread(p, t);
173 unlock_task_sighand(p, &flags);
174 autogroup_kref_put(prev);
177 /* Allocates GFP_KERNEL, cannot be called under any spinlock */
178 void sched_autogroup_create_attach(struct task_struct *p)
180 struct autogroup *ag = autogroup_create();
182 autogroup_move_group(p, ag);
183 /* drop extra refrence added by autogroup_create() */
184 autogroup_kref_put(ag);
186 EXPORT_SYMBOL(sched_autogroup_create_attach);
188 /* Cannot be called under siglock. Currently has no users */
189 void sched_autogroup_detach(struct task_struct *p)
191 autogroup_move_group(p, &autogroup_default);
193 EXPORT_SYMBOL(sched_autogroup_detach);
195 void sched_autogroup_fork(struct signal_struct *sig)
197 sig->autogroup = autogroup_task_get(current);
200 void sched_autogroup_exit(struct signal_struct *sig)
202 autogroup_kref_put(sig->autogroup);
205 static int __init setup_autogroup(char *str)
207 sysctl_sched_autogroup_enabled = 0;
212 __setup("noautogroup", setup_autogroup);
214 #ifdef CONFIG_PROC_FS
216 int proc_sched_autogroup_set_nice(struct task_struct *p, int *nice)
218 static unsigned long next = INITIAL_JIFFIES;
219 struct autogroup *ag;
222 if (*nice < -20 || *nice > 19)
225 err = security_task_setnice(current, *nice);
229 if (*nice < 0 && !can_nice(current, *nice))
232 /* this is a heavy operation taking global locks.. */
233 if (!capable(CAP_SYS_ADMIN) && time_before(jiffies, next))
236 next = HZ / 10 + jiffies;
237 ag = autogroup_task_get(p);
239 down_write(&ag->lock);
240 err = sched_group_set_shares(ag->tg, prio_to_weight[*nice + 20]);
245 autogroup_kref_put(ag);
250 void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m)
252 struct autogroup *ag = autogroup_task_get(p);
254 down_read(&ag->lock);
255 seq_printf(m, "/autogroup-%ld nice %d\n", ag->id, ag->nice);
258 autogroup_kref_put(ag);
260 #endif /* CONFIG_PROC_FS */
262 #ifdef CONFIG_SCHED_DEBUG
263 static inline int autogroup_path(struct task_group *tg, char *buf, int buflen)
265 int enabled = ACCESS_ONCE(sysctl_sched_autogroup_enabled);
267 if (!enabled || !tg->autogroup)
270 return snprintf(buf, buflen, "%s-%ld", "/autogroup", tg->autogroup->id);
272 #endif /* CONFIG_SCHED_DEBUG */
274 #endif /* CONFIG_SCHED_AUTOGROUP */