iwlagn: split remain-on-channel
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / kernel / sched_autogroup.c
blob429242f3c48485f35f2173aa3ea0cd8f8baac9a8
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 kref_init(&autogroup_default.kref);
16 init_rwsem(&autogroup_default.lock);
17 init_task->signal->autogroup = &autogroup_default;
20 static inline void autogroup_free(struct task_group *tg)
22 kfree(tg->autogroup);
25 static inline void autogroup_destroy(struct kref *kref)
27 struct autogroup *ag = container_of(kref, struct autogroup, kref);
29 #ifdef CONFIG_RT_GROUP_SCHED
30 /* We've redirected RT tasks to the root task group... */
31 ag->tg->rt_se = NULL;
32 ag->tg->rt_rq = NULL;
33 #endif
34 sched_destroy_group(ag->tg);
37 static inline void autogroup_kref_put(struct autogroup *ag)
39 kref_put(&ag->kref, autogroup_destroy);
42 static inline struct autogroup *autogroup_kref_get(struct autogroup *ag)
44 kref_get(&ag->kref);
45 return ag;
48 static inline struct autogroup *autogroup_task_get(struct task_struct *p)
50 struct autogroup *ag;
51 unsigned long flags;
53 if (!lock_task_sighand(p, &flags))
54 return autogroup_kref_get(&autogroup_default);
56 ag = autogroup_kref_get(p->signal->autogroup);
57 unlock_task_sighand(p, &flags);
59 return ag;
62 #ifdef CONFIG_RT_GROUP_SCHED
63 static void free_rt_sched_group(struct task_group *tg);
64 #endif
66 static inline struct autogroup *autogroup_create(void)
68 struct autogroup *ag = kzalloc(sizeof(*ag), GFP_KERNEL);
69 struct task_group *tg;
71 if (!ag)
72 goto out_fail;
74 tg = sched_create_group(&root_task_group);
76 if (IS_ERR(tg))
77 goto out_free;
79 kref_init(&ag->kref);
80 init_rwsem(&ag->lock);
81 ag->id = atomic_inc_return(&autogroup_seq_nr);
82 ag->tg = tg;
83 #ifdef CONFIG_RT_GROUP_SCHED
85 * Autogroup RT tasks are redirected to the root task group
86 * so we don't have to move tasks around upon policy change,
87 * or flail around trying to allocate bandwidth on the fly.
88 * A bandwidth exception in __sched_setscheduler() allows
89 * the policy change to proceed. Thereafter, task_group()
90 * returns &root_task_group, so zero bandwidth is required.
92 free_rt_sched_group(tg);
93 tg->rt_se = root_task_group.rt_se;
94 tg->rt_rq = root_task_group.rt_rq;
95 #endif
96 tg->autogroup = ag;
98 return ag;
100 out_free:
101 kfree(ag);
102 out_fail:
103 if (printk_ratelimit()) {
104 printk(KERN_WARNING "autogroup_create: %s failure.\n",
105 ag ? "sched_create_group()" : "kmalloc()");
108 return autogroup_kref_get(&autogroup_default);
111 static inline bool
112 task_wants_autogroup(struct task_struct *p, struct task_group *tg)
114 if (tg != &root_task_group)
115 return false;
117 if (p->sched_class != &fair_sched_class)
118 return false;
121 * We can only assume the task group can't go away on us if
122 * autogroup_move_group() can see us on ->thread_group list.
124 if (p->flags & PF_EXITING)
125 return false;
127 return true;
130 static inline bool task_group_is_autogroup(struct task_group *tg)
132 return !!tg->autogroup;
135 static inline struct task_group *
136 autogroup_task_group(struct task_struct *p, struct task_group *tg)
138 int enabled = ACCESS_ONCE(sysctl_sched_autogroup_enabled);
140 if (enabled && task_wants_autogroup(p, tg))
141 return p->signal->autogroup->tg;
143 return tg;
146 static void
147 autogroup_move_group(struct task_struct *p, struct autogroup *ag)
149 struct autogroup *prev;
150 struct task_struct *t;
151 unsigned long flags;
153 BUG_ON(!lock_task_sighand(p, &flags));
155 prev = p->signal->autogroup;
156 if (prev == ag) {
157 unlock_task_sighand(p, &flags);
158 return;
161 p->signal->autogroup = autogroup_kref_get(ag);
163 if (!ACCESS_ONCE(sysctl_sched_autogroup_enabled))
164 goto out;
166 t = p;
167 do {
168 sched_move_task(t);
169 } while_each_thread(p, t);
171 out:
172 unlock_task_sighand(p, &flags);
173 autogroup_kref_put(prev);
176 /* Allocates GFP_KERNEL, cannot be called under any spinlock */
177 void sched_autogroup_create_attach(struct task_struct *p)
179 struct autogroup *ag = autogroup_create();
181 autogroup_move_group(p, ag);
182 /* drop extra reference added by autogroup_create() */
183 autogroup_kref_put(ag);
185 EXPORT_SYMBOL(sched_autogroup_create_attach);
187 /* Cannot be called under siglock. Currently has no users */
188 void sched_autogroup_detach(struct task_struct *p)
190 autogroup_move_group(p, &autogroup_default);
192 EXPORT_SYMBOL(sched_autogroup_detach);
194 void sched_autogroup_fork(struct signal_struct *sig)
196 sig->autogroup = autogroup_task_get(current);
199 void sched_autogroup_exit(struct signal_struct *sig)
201 autogroup_kref_put(sig->autogroup);
204 static int __init setup_autogroup(char *str)
206 sysctl_sched_autogroup_enabled = 0;
208 return 1;
211 __setup("noautogroup", setup_autogroup);
213 #ifdef CONFIG_PROC_FS
215 int proc_sched_autogroup_set_nice(struct task_struct *p, int *nice)
217 static unsigned long next = INITIAL_JIFFIES;
218 struct autogroup *ag;
219 int err;
221 if (*nice < -20 || *nice > 19)
222 return -EINVAL;
224 err = security_task_setnice(current, *nice);
225 if (err)
226 return err;
228 if (*nice < 0 && !can_nice(current, *nice))
229 return -EPERM;
231 /* this is a heavy operation taking global locks.. */
232 if (!capable(CAP_SYS_ADMIN) && time_before(jiffies, next))
233 return -EAGAIN;
235 next = HZ / 10 + jiffies;
236 ag = autogroup_task_get(p);
238 down_write(&ag->lock);
239 err = sched_group_set_shares(ag->tg, prio_to_weight[*nice + 20]);
240 if (!err)
241 ag->nice = *nice;
242 up_write(&ag->lock);
244 autogroup_kref_put(ag);
246 return err;
249 void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m)
251 struct autogroup *ag = autogroup_task_get(p);
253 if (!task_group_is_autogroup(ag->tg))
254 goto out;
256 down_read(&ag->lock);
257 seq_printf(m, "/autogroup-%ld nice %d\n", ag->id, ag->nice);
258 up_read(&ag->lock);
260 out:
261 autogroup_kref_put(ag);
263 #endif /* CONFIG_PROC_FS */
265 #ifdef CONFIG_SCHED_DEBUG
266 static inline int autogroup_path(struct task_group *tg, char *buf, int buflen)
268 if (!task_group_is_autogroup(tg))
269 return 0;
271 return snprintf(buf, buflen, "%s-%ld", "/autogroup", tg->autogroup->id);
273 #endif /* CONFIG_SCHED_DEBUG */
275 #endif /* CONFIG_SCHED_AUTOGROUP */