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029632fb PZ |
1 | #include "sched.h" |
2 | ||
5091faa4 MG |
3 | #include <linux/proc_fs.h> |
4 | #include <linux/seq_file.h> | |
5 | #include <linux/kallsyms.h> | |
6 | #include <linux/utsname.h> | |
029632fb PZ |
7 | #include <linux/security.h> |
8 | #include <linux/export.h> | |
5091faa4 MG |
9 | |
10 | unsigned int __read_mostly sysctl_sched_autogroup_enabled = 1; | |
11 | static struct autogroup autogroup_default; | |
12 | static atomic_t autogroup_seq_nr; | |
13 | ||
029632fb | 14 | void __init autogroup_init(struct task_struct *init_task) |
5091faa4 | 15 | { |
07e06b01 | 16 | autogroup_default.tg = &root_task_group; |
5091faa4 MG |
17 | kref_init(&autogroup_default.kref); |
18 | init_rwsem(&autogroup_default.lock); | |
19 | init_task->signal->autogroup = &autogroup_default; | |
20 | } | |
21 | ||
029632fb | 22 | void autogroup_free(struct task_group *tg) |
5091faa4 MG |
23 | { |
24 | kfree(tg->autogroup); | |
25 | } | |
26 | ||
27 | static inline void autogroup_destroy(struct kref *kref) | |
28 | { | |
29 | struct autogroup *ag = container_of(kref, struct autogroup, kref); | |
30 | ||
f4493771 MG |
31 | #ifdef CONFIG_RT_GROUP_SCHED |
32 | /* We've redirected RT tasks to the root task group... */ | |
33 | ag->tg->rt_se = NULL; | |
34 | ag->tg->rt_rq = NULL; | |
35 | #endif | |
ace783b9 | 36 | sched_offline_group(ag->tg); |
5091faa4 MG |
37 | sched_destroy_group(ag->tg); |
38 | } | |
39 | ||
40 | static inline void autogroup_kref_put(struct autogroup *ag) | |
41 | { | |
42 | kref_put(&ag->kref, autogroup_destroy); | |
43 | } | |
44 | ||
45 | static inline struct autogroup *autogroup_kref_get(struct autogroup *ag) | |
46 | { | |
47 | kref_get(&ag->kref); | |
48 | return ag; | |
49 | } | |
50 | ||
4f821987 MG |
51 | static inline struct autogroup *autogroup_task_get(struct task_struct *p) |
52 | { | |
53 | struct autogroup *ag; | |
54 | unsigned long flags; | |
55 | ||
56 | if (!lock_task_sighand(p, &flags)) | |
57 | return autogroup_kref_get(&autogroup_default); | |
58 | ||
59 | ag = autogroup_kref_get(p->signal->autogroup); | |
60 | unlock_task_sighand(p, &flags); | |
61 | ||
62 | return ag; | |
63 | } | |
64 | ||
5091faa4 MG |
65 | static inline struct autogroup *autogroup_create(void) |
66 | { | |
67 | struct autogroup *ag = kzalloc(sizeof(*ag), GFP_KERNEL); | |
68 | struct task_group *tg; | |
69 | ||
70 | if (!ag) | |
71 | goto out_fail; | |
72 | ||
07e06b01 | 73 | tg = sched_create_group(&root_task_group); |
5091faa4 MG |
74 | |
75 | if (IS_ERR(tg)) | |
76 | goto out_free; | |
77 | ||
78 | kref_init(&ag->kref); | |
79 | init_rwsem(&ag->lock); | |
80 | ag->id = atomic_inc_return(&autogroup_seq_nr); | |
81 | ag->tg = tg; | |
f4493771 MG |
82 | #ifdef CONFIG_RT_GROUP_SCHED |
83 | /* | |
84 | * Autogroup RT tasks are redirected to the root task group | |
85 | * so we don't have to move tasks around upon policy change, | |
86 | * or flail around trying to allocate bandwidth on the fly. | |
87 | * A bandwidth exception in __sched_setscheduler() allows | |
1fe89e1b | 88 | * the policy change to proceed. |
f4493771 MG |
89 | */ |
90 | free_rt_sched_group(tg); | |
91 | tg->rt_se = root_task_group.rt_se; | |
92 | tg->rt_rq = root_task_group.rt_rq; | |
93 | #endif | |
5091faa4 MG |
94 | tg->autogroup = ag; |
95 | ||
41261b6a | 96 | sched_online_group(tg, &root_task_group); |
5091faa4 MG |
97 | return ag; |
98 | ||
99 | out_free: | |
100 | kfree(ag); | |
101 | out_fail: | |
102 | if (printk_ratelimit()) { | |
103 | printk(KERN_WARNING "autogroup_create: %s failure.\n", | |
104 | ag ? "sched_create_group()" : "kmalloc()"); | |
105 | } | |
106 | ||
107 | return autogroup_kref_get(&autogroup_default); | |
108 | } | |
109 | ||
029632fb | 110 | bool task_wants_autogroup(struct task_struct *p, struct task_group *tg) |
5091faa4 MG |
111 | { |
112 | if (tg != &root_task_group) | |
113 | return false; | |
5091faa4 | 114 | /* |
18f649ef ON |
115 | * If we race with autogroup_move_group() the caller can use the old |
116 | * value of signal->autogroup but in this case sched_move_task() will | |
117 | * be called again before autogroup_kref_put(). | |
8e5bfa8c ON |
118 | * |
119 | * However, there is no way sched_autogroup_exit_task() could tell us | |
120 | * to avoid autogroup->tg, so we abuse PF_EXITING flag for this case. | |
5091faa4 | 121 | */ |
8e5bfa8c ON |
122 | if (p->flags & PF_EXITING) |
123 | return false; | |
124 | ||
5091faa4 MG |
125 | return true; |
126 | } | |
127 | ||
8e5bfa8c ON |
128 | void sched_autogroup_exit_task(struct task_struct *p) |
129 | { | |
130 | /* | |
131 | * We are going to call exit_notify() and autogroup_move_group() can't | |
132 | * see this thread after that: we can no longer use signal->autogroup. | |
133 | * See the PF_EXITING check in task_wants_autogroup(). | |
134 | */ | |
135 | sched_move_task(p); | |
136 | } | |
137 | ||
5091faa4 MG |
138 | static void |
139 | autogroup_move_group(struct task_struct *p, struct autogroup *ag) | |
140 | { | |
141 | struct autogroup *prev; | |
142 | struct task_struct *t; | |
143 | unsigned long flags; | |
144 | ||
145 | BUG_ON(!lock_task_sighand(p, &flags)); | |
146 | ||
147 | prev = p->signal->autogroup; | |
148 | if (prev == ag) { | |
149 | unlock_task_sighand(p, &flags); | |
150 | return; | |
151 | } | |
152 | ||
153 | p->signal->autogroup = autogroup_kref_get(ag); | |
18f649ef ON |
154 | /* |
155 | * We can't avoid sched_move_task() after we changed signal->autogroup, | |
156 | * this process can already run with task_group() == prev->tg or we can | |
157 | * race with cgroup code which can read autogroup = prev under rq->lock. | |
158 | * In the latter case for_each_thread() can not miss a migrating thread, | |
159 | * cpu_cgroup_attach() must not be possible after cgroup_exit() and it | |
160 | * can't be removed from thread list, we hold ->siglock. | |
8e5bfa8c ON |
161 | * |
162 | * If an exiting thread was already removed from thread list we rely on | |
163 | * sched_autogroup_exit_task(). | |
18f649ef | 164 | */ |
5aface53 | 165 | for_each_thread(p, t) |
5091faa4 | 166 | sched_move_task(t); |
18f649ef | 167 | |
5091faa4 MG |
168 | unlock_task_sighand(p, &flags); |
169 | autogroup_kref_put(prev); | |
170 | } | |
171 | ||
172 | /* Allocates GFP_KERNEL, cannot be called under any spinlock */ | |
173 | void sched_autogroup_create_attach(struct task_struct *p) | |
174 | { | |
c1ad41f1 | 175 | struct autogroup *ag = autogroup_create(); |
5091faa4 MG |
176 | |
177 | autogroup_move_group(p, ag); | |
25985edc | 178 | /* drop extra reference added by autogroup_create() */ |
5091faa4 MG |
179 | autogroup_kref_put(ag); |
180 | } | |
181 | EXPORT_SYMBOL(sched_autogroup_create_attach); | |
182 | ||
183 | /* Cannot be called under siglock. Currently has no users */ | |
184 | void sched_autogroup_detach(struct task_struct *p) | |
185 | { | |
186 | autogroup_move_group(p, &autogroup_default); | |
187 | } | |
188 | EXPORT_SYMBOL(sched_autogroup_detach); | |
189 | ||
190 | void sched_autogroup_fork(struct signal_struct *sig) | |
191 | { | |
4f821987 | 192 | sig->autogroup = autogroup_task_get(current); |
5091faa4 MG |
193 | } |
194 | ||
195 | void sched_autogroup_exit(struct signal_struct *sig) | |
196 | { | |
197 | autogroup_kref_put(sig->autogroup); | |
198 | } | |
199 | ||
200 | static int __init setup_autogroup(char *str) | |
201 | { | |
202 | sysctl_sched_autogroup_enabled = 0; | |
203 | ||
204 | return 1; | |
205 | } | |
206 | ||
207 | __setup("noautogroup", setup_autogroup); | |
208 | ||
c1ad41f1 IM |
209 | #ifdef CONFIG_PROC_FS |
210 | ||
211 | int proc_sched_autogroup_set_nice(struct task_struct *p, int nice) | |
212 | { | |
213 | static unsigned long next = INITIAL_JIFFIES; | |
214 | struct autogroup *ag; | |
83929cce | 215 | unsigned long shares; |
c1ad41f1 IM |
216 | int err; |
217 | ||
75e45d51 | 218 | if (nice < MIN_NICE || nice > MAX_NICE) |
c1ad41f1 IM |
219 | return -EINVAL; |
220 | ||
221 | err = security_task_setnice(current, nice); | |
222 | if (err) | |
223 | return err; | |
224 | ||
225 | if (nice < 0 && !can_nice(current, nice)) | |
226 | return -EPERM; | |
227 | ||
228 | /* this is a heavy operation taking global locks.. */ | |
229 | if (!capable(CAP_SYS_ADMIN) && time_before(jiffies, next)) | |
230 | return -EAGAIN; | |
231 | ||
232 | next = HZ / 10 + jiffies; | |
233 | ag = autogroup_task_get(p); | |
83929cce | 234 | shares = scale_load(sched_prio_to_weight[nice + 20]); |
c1ad41f1 IM |
235 | |
236 | down_write(&ag->lock); | |
83929cce | 237 | err = sched_group_set_shares(ag->tg, shares); |
c1ad41f1 IM |
238 | if (!err) |
239 | ag->nice = nice; | |
240 | up_write(&ag->lock); | |
241 | ||
242 | autogroup_kref_put(ag); | |
243 | ||
244 | return err; | |
245 | } | |
246 | ||
247 | void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m) | |
248 | { | |
249 | struct autogroup *ag = autogroup_task_get(p); | |
250 | ||
251 | if (!task_group_is_autogroup(ag->tg)) | |
252 | goto out; | |
253 | ||
254 | down_read(&ag->lock); | |
255 | seq_printf(m, "/autogroup-%ld nice %d\n", ag->id, ag->nice); | |
256 | up_read(&ag->lock); | |
257 | ||
258 | out: | |
259 | autogroup_kref_put(ag); | |
260 | } | |
261 | #endif /* CONFIG_PROC_FS */ | |
262 | ||
5091faa4 | 263 | #ifdef CONFIG_SCHED_DEBUG |
029632fb | 264 | int autogroup_path(struct task_group *tg, char *buf, int buflen) |
5091faa4 | 265 | { |
511f67a5 | 266 | if (!task_group_is_autogroup(tg)) |
8ecedd7a BR |
267 | return 0; |
268 | ||
5091faa4 MG |
269 | return snprintf(buf, buflen, "%s-%ld", "/autogroup", tg->autogroup->id); |
270 | } | |
271 | #endif /* CONFIG_SCHED_DEBUG */ |