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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 YZ |
14 | autogroup_default.tg = &root_task_group; |
15 | root_task_group.autogroup = &autogroup_default; | |
5091faa4 MG |
16 | kref_init(&autogroup_default.kref); |
17 | init_rwsem(&autogroup_default.lock); | |
18 | init_task->signal->autogroup = &autogroup_default; | |
19 | } | |
20 | ||
21 | static inline void autogroup_free(struct task_group *tg) | |
22 | { | |
23 | kfree(tg->autogroup); | |
24 | } | |
25 | ||
26 | static inline void autogroup_destroy(struct kref *kref) | |
27 | { | |
28 | struct autogroup *ag = container_of(kref, struct autogroup, kref); | |
29 | ||
f4493771 MG |
30 | #ifdef CONFIG_RT_GROUP_SCHED |
31 | /* We've redirected RT tasks to the root task group... */ | |
32 | ag->tg->rt_se = NULL; | |
33 | ag->tg->rt_rq = NULL; | |
34 | #endif | |
5091faa4 MG |
35 | sched_destroy_group(ag->tg); |
36 | } | |
37 | ||
38 | static inline void autogroup_kref_put(struct autogroup *ag) | |
39 | { | |
40 | kref_put(&ag->kref, autogroup_destroy); | |
41 | } | |
42 | ||
43 | static inline struct autogroup *autogroup_kref_get(struct autogroup *ag) | |
44 | { | |
45 | kref_get(&ag->kref); | |
46 | return ag; | |
47 | } | |
48 | ||
4f821987 MG |
49 | static inline struct autogroup *autogroup_task_get(struct task_struct *p) |
50 | { | |
51 | struct autogroup *ag; | |
52 | unsigned long flags; | |
53 | ||
54 | if (!lock_task_sighand(p, &flags)) | |
55 | return autogroup_kref_get(&autogroup_default); | |
56 | ||
57 | ag = autogroup_kref_get(p->signal->autogroup); | |
58 | unlock_task_sighand(p, &flags); | |
59 | ||
60 | return ag; | |
61 | } | |
62 | ||
f4493771 MG |
63 | #ifdef CONFIG_RT_GROUP_SCHED |
64 | static void free_rt_sched_group(struct task_group *tg); | |
65 | #endif | |
66 | ||
5091faa4 MG |
67 | static inline struct autogroup *autogroup_create(void) |
68 | { | |
69 | struct autogroup *ag = kzalloc(sizeof(*ag), GFP_KERNEL); | |
70 | struct task_group *tg; | |
71 | ||
72 | if (!ag) | |
73 | goto out_fail; | |
74 | ||
07e06b01 | 75 | tg = sched_create_group(&root_task_group); |
5091faa4 MG |
76 | |
77 | if (IS_ERR(tg)) | |
78 | goto out_free; | |
79 | ||
80 | kref_init(&ag->kref); | |
81 | init_rwsem(&ag->lock); | |
82 | ag->id = atomic_inc_return(&autogroup_seq_nr); | |
83 | ag->tg = tg; | |
f4493771 MG |
84 | #ifdef CONFIG_RT_GROUP_SCHED |
85 | /* | |
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. | |
92 | */ | |
93 | free_rt_sched_group(tg); | |
94 | tg->rt_se = root_task_group.rt_se; | |
95 | tg->rt_rq = root_task_group.rt_rq; | |
96 | #endif | |
5091faa4 MG |
97 | tg->autogroup = ag; |
98 | ||
99 | return ag; | |
100 | ||
101 | out_free: | |
102 | kfree(ag); | |
103 | out_fail: | |
104 | if (printk_ratelimit()) { | |
105 | printk(KERN_WARNING "autogroup_create: %s failure.\n", | |
106 | ag ? "sched_create_group()" : "kmalloc()"); | |
107 | } | |
108 | ||
109 | return autogroup_kref_get(&autogroup_default); | |
110 | } | |
111 | ||
112 | static inline bool | |
113 | task_wants_autogroup(struct task_struct *p, struct task_group *tg) | |
114 | { | |
115 | if (tg != &root_task_group) | |
116 | return false; | |
117 | ||
118 | if (p->sched_class != &fair_sched_class) | |
119 | return false; | |
120 | ||
121 | /* | |
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. | |
124 | */ | |
125 | if (p->flags & PF_EXITING) | |
126 | return false; | |
127 | ||
128 | return true; | |
129 | } | |
130 | ||
f4493771 MG |
131 | static inline bool task_group_is_autogroup(struct task_group *tg) |
132 | { | |
133 | return tg != &root_task_group && tg->autogroup; | |
134 | } | |
135 | ||
5091faa4 MG |
136 | static inline struct task_group * |
137 | autogroup_task_group(struct task_struct *p, struct task_group *tg) | |
138 | { | |
139 | int enabled = ACCESS_ONCE(sysctl_sched_autogroup_enabled); | |
140 | ||
141 | if (enabled && task_wants_autogroup(p, tg)) | |
142 | return p->signal->autogroup->tg; | |
143 | ||
144 | return tg; | |
145 | } | |
146 | ||
147 | static void | |
148 | autogroup_move_group(struct task_struct *p, struct autogroup *ag) | |
149 | { | |
150 | struct autogroup *prev; | |
151 | struct task_struct *t; | |
152 | unsigned long flags; | |
153 | ||
154 | BUG_ON(!lock_task_sighand(p, &flags)); | |
155 | ||
156 | prev = p->signal->autogroup; | |
157 | if (prev == ag) { | |
158 | unlock_task_sighand(p, &flags); | |
159 | return; | |
160 | } | |
161 | ||
162 | p->signal->autogroup = autogroup_kref_get(ag); | |
163 | ||
164 | t = p; | |
165 | do { | |
166 | sched_move_task(t); | |
167 | } while_each_thread(p, t); | |
168 | ||
169 | unlock_task_sighand(p, &flags); | |
170 | autogroup_kref_put(prev); | |
171 | } | |
172 | ||
173 | /* Allocates GFP_KERNEL, cannot be called under any spinlock */ | |
174 | void sched_autogroup_create_attach(struct task_struct *p) | |
175 | { | |
176 | struct autogroup *ag = autogroup_create(); | |
177 | ||
178 | autogroup_move_group(p, ag); | |
179 | /* drop extra refrence added by autogroup_create() */ | |
180 | autogroup_kref_put(ag); | |
181 | } | |
182 | EXPORT_SYMBOL(sched_autogroup_create_attach); | |
183 | ||
184 | /* Cannot be called under siglock. Currently has no users */ | |
185 | void sched_autogroup_detach(struct task_struct *p) | |
186 | { | |
187 | autogroup_move_group(p, &autogroup_default); | |
188 | } | |
189 | EXPORT_SYMBOL(sched_autogroup_detach); | |
190 | ||
191 | void sched_autogroup_fork(struct signal_struct *sig) | |
192 | { | |
4f821987 | 193 | sig->autogroup = autogroup_task_get(current); |
5091faa4 MG |
194 | } |
195 | ||
196 | void sched_autogroup_exit(struct signal_struct *sig) | |
197 | { | |
198 | autogroup_kref_put(sig->autogroup); | |
199 | } | |
200 | ||
201 | static int __init setup_autogroup(char *str) | |
202 | { | |
203 | sysctl_sched_autogroup_enabled = 0; | |
204 | ||
205 | return 1; | |
206 | } | |
207 | ||
208 | __setup("noautogroup", setup_autogroup); | |
209 | ||
210 | #ifdef CONFIG_PROC_FS | |
211 | ||
5091faa4 MG |
212 | int proc_sched_autogroup_set_nice(struct task_struct *p, int *nice) |
213 | { | |
214 | static unsigned long next = INITIAL_JIFFIES; | |
215 | struct autogroup *ag; | |
216 | int err; | |
217 | ||
218 | if (*nice < -20 || *nice > 19) | |
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; | |
4f821987 | 233 | ag = autogroup_task_get(p); |
5091faa4 MG |
234 | |
235 | down_write(&ag->lock); | |
236 | err = sched_group_set_shares(ag->tg, prio_to_weight[*nice + 20]); | |
237 | if (!err) | |
238 | ag->nice = *nice; | |
239 | up_write(&ag->lock); | |
240 | ||
241 | autogroup_kref_put(ag); | |
242 | ||
243 | return err; | |
244 | } | |
245 | ||
246 | void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m) | |
247 | { | |
4f821987 | 248 | struct autogroup *ag = autogroup_task_get(p); |
5091faa4 MG |
249 | |
250 | down_read(&ag->lock); | |
251 | seq_printf(m, "/autogroup-%ld nice %d\n", ag->id, ag->nice); | |
252 | up_read(&ag->lock); | |
253 | ||
254 | autogroup_kref_put(ag); | |
255 | } | |
256 | #endif /* CONFIG_PROC_FS */ | |
257 | ||
258 | #ifdef CONFIG_SCHED_DEBUG | |
259 | static inline int autogroup_path(struct task_group *tg, char *buf, int buflen) | |
260 | { | |
8ecedd7a BR |
261 | int enabled = ACCESS_ONCE(sysctl_sched_autogroup_enabled); |
262 | ||
263 | if (!enabled || !tg->autogroup) | |
264 | return 0; | |
265 | ||
5091faa4 MG |
266 | return snprintf(buf, buflen, "%s-%ld", "/autogroup", tg->autogroup->id); |
267 | } | |
268 | #endif /* CONFIG_SCHED_DEBUG */ | |
269 | ||
270 | #endif /* CONFIG_SCHED_AUTOGROUP */ |