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5091faa4 MG |
1 | #ifdef CONFIG_SCHED_AUTOGROUP |
2 | ||
3 | #include <linux/proc_fs.h> | |
4 | #include <linux/seq_file.h> | |
5 | #include <linux/kallsyms.h> | |
6 | #include <linux/utsname.h> | |
7 | ||
8 | unsigned int __read_mostly sysctl_sched_autogroup_enabled = 1; | |
9 | static struct autogroup autogroup_default; | |
10 | static atomic_t autogroup_seq_nr; | |
11 | ||
0ca08735 | 12 | static void __init autogroup_init(struct task_struct *init_task) |
5091faa4 | 13 | { |
07e06b01 | 14 | autogroup_default.tg = &root_task_group; |
5091faa4 MG |
15 | kref_init(&autogroup_default.kref); |
16 | init_rwsem(&autogroup_default.lock); | |
17 | init_task->signal->autogroup = &autogroup_default; | |
18 | } | |
19 | ||
20 | static inline void autogroup_free(struct task_group *tg) | |
21 | { | |
22 | kfree(tg->autogroup); | |
23 | } | |
24 | ||
25 | static inline void autogroup_destroy(struct kref *kref) | |
26 | { | |
27 | struct autogroup *ag = container_of(kref, struct autogroup, kref); | |
28 | ||
f4493771 MG |
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 | |
5091faa4 MG |
34 | sched_destroy_group(ag->tg); |
35 | } | |
36 | ||
37 | static inline void autogroup_kref_put(struct autogroup *ag) | |
38 | { | |
39 | kref_put(&ag->kref, autogroup_destroy); | |
40 | } | |
41 | ||
42 | static inline struct autogroup *autogroup_kref_get(struct autogroup *ag) | |
43 | { | |
44 | kref_get(&ag->kref); | |
45 | return ag; | |
46 | } | |
47 | ||
4f821987 MG |
48 | static inline struct autogroup *autogroup_task_get(struct task_struct *p) |
49 | { | |
50 | struct autogroup *ag; | |
51 | unsigned long flags; | |
52 | ||
53 | if (!lock_task_sighand(p, &flags)) | |
54 | return autogroup_kref_get(&autogroup_default); | |
55 | ||
56 | ag = autogroup_kref_get(p->signal->autogroup); | |
57 | unlock_task_sighand(p, &flags); | |
58 | ||
59 | return ag; | |
60 | } | |
61 | ||
f4493771 MG |
62 | #ifdef CONFIG_RT_GROUP_SCHED |
63 | static void free_rt_sched_group(struct task_group *tg); | |
64 | #endif | |
65 | ||
5091faa4 MG |
66 | static inline struct autogroup *autogroup_create(void) |
67 | { | |
68 | struct autogroup *ag = kzalloc(sizeof(*ag), GFP_KERNEL); | |
69 | struct task_group *tg; | |
70 | ||
71 | if (!ag) | |
72 | goto out_fail; | |
73 | ||
07e06b01 | 74 | tg = sched_create_group(&root_task_group); |
5091faa4 MG |
75 | |
76 | if (IS_ERR(tg)) | |
77 | goto out_free; | |
78 | ||
79 | kref_init(&ag->kref); | |
80 | init_rwsem(&ag->lock); | |
81 | ag->id = atomic_inc_return(&autogroup_seq_nr); | |
82 | ag->tg = tg; | |
f4493771 MG |
83 | #ifdef CONFIG_RT_GROUP_SCHED |
84 | /* | |
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. | |
91 | */ | |
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 | |
5091faa4 MG |
96 | tg->autogroup = ag; |
97 | ||
98 | return ag; | |
99 | ||
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()"); | |
106 | } | |
107 | ||
108 | return autogroup_kref_get(&autogroup_default); | |
109 | } | |
110 | ||
111 | static inline bool | |
112 | task_wants_autogroup(struct task_struct *p, struct task_group *tg) | |
113 | { | |
114 | if (tg != &root_task_group) | |
115 | return false; | |
116 | ||
117 | if (p->sched_class != &fair_sched_class) | |
118 | return false; | |
119 | ||
120 | /* | |
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. | |
123 | */ | |
124 | if (p->flags & PF_EXITING) | |
125 | return false; | |
126 | ||
127 | return true; | |
128 | } | |
129 | ||
f4493771 MG |
130 | static inline bool task_group_is_autogroup(struct task_group *tg) |
131 | { | |
511f67a5 | 132 | return !!tg->autogroup; |
f4493771 MG |
133 | } |
134 | ||
5091faa4 MG |
135 | static inline struct task_group * |
136 | autogroup_task_group(struct task_struct *p, struct task_group *tg) | |
137 | { | |
138 | int enabled = ACCESS_ONCE(sysctl_sched_autogroup_enabled); | |
139 | ||
140 | if (enabled && task_wants_autogroup(p, tg)) | |
141 | return p->signal->autogroup->tg; | |
142 | ||
143 | return tg; | |
144 | } | |
145 | ||
146 | static void | |
147 | autogroup_move_group(struct task_struct *p, struct autogroup *ag) | |
148 | { | |
149 | struct autogroup *prev; | |
150 | struct task_struct *t; | |
151 | unsigned long flags; | |
152 | ||
153 | BUG_ON(!lock_task_sighand(p, &flags)); | |
154 | ||
155 | prev = p->signal->autogroup; | |
156 | if (prev == ag) { | |
157 | unlock_task_sighand(p, &flags); | |
158 | return; | |
159 | } | |
160 | ||
161 | p->signal->autogroup = autogroup_kref_get(ag); | |
162 | ||
800d4d30 YZ |
163 | if (!ACCESS_ONCE(sysctl_sched_autogroup_enabled)) |
164 | goto out; | |
165 | ||
5091faa4 MG |
166 | t = p; |
167 | do { | |
168 | sched_move_task(t); | |
169 | } while_each_thread(p, t); | |
170 | ||
800d4d30 | 171 | out: |
5091faa4 MG |
172 | unlock_task_sighand(p, &flags); |
173 | autogroup_kref_put(prev); | |
174 | } | |
175 | ||
176 | /* Allocates GFP_KERNEL, cannot be called under any spinlock */ | |
177 | void sched_autogroup_create_attach(struct task_struct *p) | |
178 | { | |
179 | struct autogroup *ag = autogroup_create(); | |
180 | ||
181 | autogroup_move_group(p, ag); | |
182 | /* drop extra refrence added by autogroup_create() */ | |
183 | autogroup_kref_put(ag); | |
184 | } | |
185 | EXPORT_SYMBOL(sched_autogroup_create_attach); | |
186 | ||
187 | /* Cannot be called under siglock. Currently has no users */ | |
188 | void sched_autogroup_detach(struct task_struct *p) | |
189 | { | |
190 | autogroup_move_group(p, &autogroup_default); | |
191 | } | |
192 | EXPORT_SYMBOL(sched_autogroup_detach); | |
193 | ||
194 | void sched_autogroup_fork(struct signal_struct *sig) | |
195 | { | |
4f821987 | 196 | sig->autogroup = autogroup_task_get(current); |
5091faa4 MG |
197 | } |
198 | ||
199 | void sched_autogroup_exit(struct signal_struct *sig) | |
200 | { | |
201 | autogroup_kref_put(sig->autogroup); | |
202 | } | |
203 | ||
204 | static int __init setup_autogroup(char *str) | |
205 | { | |
206 | sysctl_sched_autogroup_enabled = 0; | |
207 | ||
208 | return 1; | |
209 | } | |
210 | ||
211 | __setup("noautogroup", setup_autogroup); | |
212 | ||
213 | #ifdef CONFIG_PROC_FS | |
214 | ||
5091faa4 MG |
215 | int proc_sched_autogroup_set_nice(struct task_struct *p, int *nice) |
216 | { | |
217 | static unsigned long next = INITIAL_JIFFIES; | |
218 | struct autogroup *ag; | |
219 | int err; | |
220 | ||
221 | if (*nice < -20 || *nice > 19) | |
222 | return -EINVAL; | |
223 | ||
224 | err = security_task_setnice(current, *nice); | |
225 | if (err) | |
226 | return err; | |
227 | ||
228 | if (*nice < 0 && !can_nice(current, *nice)) | |
229 | return -EPERM; | |
230 | ||
231 | /* this is a heavy operation taking global locks.. */ | |
232 | if (!capable(CAP_SYS_ADMIN) && time_before(jiffies, next)) | |
233 | return -EAGAIN; | |
234 | ||
235 | next = HZ / 10 + jiffies; | |
4f821987 | 236 | ag = autogroup_task_get(p); |
5091faa4 MG |
237 | |
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); | |
243 | ||
244 | autogroup_kref_put(ag); | |
245 | ||
246 | return err; | |
247 | } | |
248 | ||
249 | void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m) | |
250 | { | |
4f821987 | 251 | struct autogroup *ag = autogroup_task_get(p); |
5091faa4 | 252 | |
511f67a5 MG |
253 | if (!task_group_is_autogroup(ag->tg)) |
254 | goto out; | |
255 | ||
5091faa4 MG |
256 | down_read(&ag->lock); |
257 | seq_printf(m, "/autogroup-%ld nice %d\n", ag->id, ag->nice); | |
258 | up_read(&ag->lock); | |
259 | ||
511f67a5 | 260 | out: |
5091faa4 MG |
261 | autogroup_kref_put(ag); |
262 | } | |
263 | #endif /* CONFIG_PROC_FS */ | |
264 | ||
265 | #ifdef CONFIG_SCHED_DEBUG | |
266 | static inline int autogroup_path(struct task_group *tg, char *buf, int buflen) | |
267 | { | |
511f67a5 | 268 | if (!task_group_is_autogroup(tg)) |
8ecedd7a BR |
269 | return 0; |
270 | ||
5091faa4 MG |
271 | return snprintf(buf, buflen, "%s-%ld", "/autogroup", tg->autogroup->id); |
272 | } | |
273 | #endif /* CONFIG_SCHED_DEBUG */ | |
274 | ||
275 | #endif /* CONFIG_SCHED_AUTOGROUP */ |