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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(). | |
5091faa4 | 118 | */ |
5091faa4 MG |
119 | return true; |
120 | } | |
121 | ||
5091faa4 MG |
122 | static void |
123 | autogroup_move_group(struct task_struct *p, struct autogroup *ag) | |
124 | { | |
125 | struct autogroup *prev; | |
126 | struct task_struct *t; | |
127 | unsigned long flags; | |
128 | ||
129 | BUG_ON(!lock_task_sighand(p, &flags)); | |
130 | ||
131 | prev = p->signal->autogroup; | |
132 | if (prev == ag) { | |
133 | unlock_task_sighand(p, &flags); | |
134 | return; | |
135 | } | |
136 | ||
137 | p->signal->autogroup = autogroup_kref_get(ag); | |
18f649ef ON |
138 | /* |
139 | * We can't avoid sched_move_task() after we changed signal->autogroup, | |
140 | * this process can already run with task_group() == prev->tg or we can | |
141 | * race with cgroup code which can read autogroup = prev under rq->lock. | |
142 | * In the latter case for_each_thread() can not miss a migrating thread, | |
143 | * cpu_cgroup_attach() must not be possible after cgroup_exit() and it | |
144 | * can't be removed from thread list, we hold ->siglock. | |
145 | */ | |
5aface53 | 146 | for_each_thread(p, t) |
5091faa4 | 147 | sched_move_task(t); |
18f649ef | 148 | |
5091faa4 MG |
149 | unlock_task_sighand(p, &flags); |
150 | autogroup_kref_put(prev); | |
151 | } | |
152 | ||
153 | /* Allocates GFP_KERNEL, cannot be called under any spinlock */ | |
154 | void sched_autogroup_create_attach(struct task_struct *p) | |
155 | { | |
c1ad41f1 | 156 | struct autogroup *ag = autogroup_create(); |
5091faa4 MG |
157 | |
158 | autogroup_move_group(p, ag); | |
25985edc | 159 | /* drop extra reference added by autogroup_create() */ |
5091faa4 MG |
160 | autogroup_kref_put(ag); |
161 | } | |
162 | EXPORT_SYMBOL(sched_autogroup_create_attach); | |
163 | ||
164 | /* Cannot be called under siglock. Currently has no users */ | |
165 | void sched_autogroup_detach(struct task_struct *p) | |
166 | { | |
167 | autogroup_move_group(p, &autogroup_default); | |
168 | } | |
169 | EXPORT_SYMBOL(sched_autogroup_detach); | |
170 | ||
171 | void sched_autogroup_fork(struct signal_struct *sig) | |
172 | { | |
4f821987 | 173 | sig->autogroup = autogroup_task_get(current); |
5091faa4 MG |
174 | } |
175 | ||
176 | void sched_autogroup_exit(struct signal_struct *sig) | |
177 | { | |
178 | autogroup_kref_put(sig->autogroup); | |
179 | } | |
180 | ||
181 | static int __init setup_autogroup(char *str) | |
182 | { | |
183 | sysctl_sched_autogroup_enabled = 0; | |
184 | ||
185 | return 1; | |
186 | } | |
187 | ||
188 | __setup("noautogroup", setup_autogroup); | |
189 | ||
c1ad41f1 IM |
190 | #ifdef CONFIG_PROC_FS |
191 | ||
192 | int proc_sched_autogroup_set_nice(struct task_struct *p, int nice) | |
193 | { | |
194 | static unsigned long next = INITIAL_JIFFIES; | |
195 | struct autogroup *ag; | |
196 | int err; | |
197 | ||
75e45d51 | 198 | if (nice < MIN_NICE || nice > MAX_NICE) |
c1ad41f1 IM |
199 | return -EINVAL; |
200 | ||
201 | err = security_task_setnice(current, nice); | |
202 | if (err) | |
203 | return err; | |
204 | ||
205 | if (nice < 0 && !can_nice(current, nice)) | |
206 | return -EPERM; | |
207 | ||
208 | /* this is a heavy operation taking global locks.. */ | |
209 | if (!capable(CAP_SYS_ADMIN) && time_before(jiffies, next)) | |
210 | return -EAGAIN; | |
211 | ||
212 | next = HZ / 10 + jiffies; | |
213 | ag = autogroup_task_get(p); | |
214 | ||
215 | down_write(&ag->lock); | |
ed82b8a1 | 216 | err = sched_group_set_shares(ag->tg, sched_prio_to_weight[nice + 20]); |
c1ad41f1 IM |
217 | if (!err) |
218 | ag->nice = nice; | |
219 | up_write(&ag->lock); | |
220 | ||
221 | autogroup_kref_put(ag); | |
222 | ||
223 | return err; | |
224 | } | |
225 | ||
226 | void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m) | |
227 | { | |
228 | struct autogroup *ag = autogroup_task_get(p); | |
229 | ||
230 | if (!task_group_is_autogroup(ag->tg)) | |
231 | goto out; | |
232 | ||
233 | down_read(&ag->lock); | |
234 | seq_printf(m, "/autogroup-%ld nice %d\n", ag->id, ag->nice); | |
235 | up_read(&ag->lock); | |
236 | ||
237 | out: | |
238 | autogroup_kref_put(ag); | |
239 | } | |
240 | #endif /* CONFIG_PROC_FS */ | |
241 | ||
5091faa4 | 242 | #ifdef CONFIG_SCHED_DEBUG |
029632fb | 243 | int autogroup_path(struct task_group *tg, char *buf, int buflen) |
5091faa4 | 244 | { |
511f67a5 | 245 | if (!task_group_is_autogroup(tg)) |
8ecedd7a BR |
246 | return 0; |
247 | ||
5091faa4 MG |
248 | return snprintf(buf, buflen, "%s-%ld", "/autogroup", tg->autogroup->id); |
249 | } | |
250 | #endif /* CONFIG_SCHED_DEBUG */ |