1 #ifdef CONFIG_SCHED_AUTOGROUP
2
3 #include "sched.h"
4
5 #include <linux/proc_fs.h>
6 #include <linux/seq_file.h>
7 #include <linux/kallsyms.h>
8 #include <linux/utsname.h>
9 #include <linux/security.h>
10 #include <linux/export.h>
11
12 unsigned int __read_mostly sysctl_sched_autogroup_enabled = 1;
13 static struct autogroup autogroup_default;
14 static atomic_t autogroup_seq_nr;
15
autogroup_init(struct task_struct * init_task)16 void __init autogroup_init(struct task_struct *init_task)
17 {
18 autogroup_default.tg = &root_task_group;
19 kref_init(&autogroup_default.kref);
20 init_rwsem(&autogroup_default.lock);
21 init_task->signal->autogroup = &autogroup_default;
22 }
23
autogroup_free(struct task_group * tg)24 void autogroup_free(struct task_group *tg)
25 {
26 kfree(tg->autogroup);
27 }
28
autogroup_destroy(struct kref * kref)29 static inline void autogroup_destroy(struct kref *kref)
30 {
31 struct autogroup *ag = container_of(kref, struct autogroup, kref);
32
33 #ifdef CONFIG_RT_GROUP_SCHED
34 /* We've redirected RT tasks to the root task group... */
35 ag->tg->rt_se = NULL;
36 ag->tg->rt_rq = NULL;
37 #endif
38 sched_offline_group(ag->tg);
39 sched_destroy_group(ag->tg);
40 }
41
autogroup_kref_put(struct autogroup * ag)42 static inline void autogroup_kref_put(struct autogroup *ag)
43 {
44 kref_put(&ag->kref, autogroup_destroy);
45 }
46
autogroup_kref_get(struct autogroup * ag)47 static inline struct autogroup *autogroup_kref_get(struct autogroup *ag)
48 {
49 kref_get(&ag->kref);
50 return ag;
51 }
52
autogroup_task_get(struct task_struct * p)53 static inline struct autogroup *autogroup_task_get(struct task_struct *p)
54 {
55 struct autogroup *ag;
56 unsigned long flags;
57
58 if (!lock_task_sighand(p, &flags))
59 return autogroup_kref_get(&autogroup_default);
60
61 ag = autogroup_kref_get(p->signal->autogroup);
62 unlock_task_sighand(p, &flags);
63
64 return ag;
65 }
66
autogroup_create(void)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
75 tg = sched_create_group(&root_task_group);
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;
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.
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
96 tg->autogroup = ag;
97
98 sched_online_group(tg, &root_task_group);
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
task_wants_autogroup(struct task_struct * p,struct task_group * tg)112 bool task_wants_autogroup(struct task_struct *p, struct task_group *tg)
113 {
114 if (tg != &root_task_group)
115 return false;
116
117 /*
118 * We can only assume the task group can't go away on us if
119 * autogroup_move_group() can see us on ->thread_group list.
120 */
121 if (p->flags & PF_EXITING)
122 return false;
123
124 return true;
125 }
126
127 static void
autogroup_move_group(struct task_struct * p,struct autogroup * ag)128 autogroup_move_group(struct task_struct *p, struct autogroup *ag)
129 {
130 struct autogroup *prev;
131 struct task_struct *t;
132 unsigned long flags;
133
134 BUG_ON(!lock_task_sighand(p, &flags));
135
136 prev = p->signal->autogroup;
137 if (prev == ag) {
138 unlock_task_sighand(p, &flags);
139 return;
140 }
141
142 p->signal->autogroup = autogroup_kref_get(ag);
143
144 if (!READ_ONCE(sysctl_sched_autogroup_enabled))
145 goto out;
146
147 for_each_thread(p, t)
148 sched_move_task(t);
149 out:
150 unlock_task_sighand(p, &flags);
151 autogroup_kref_put(prev);
152 }
153
154 /* Allocates GFP_KERNEL, cannot be called under any spinlock */
sched_autogroup_create_attach(struct task_struct * p)155 void sched_autogroup_create_attach(struct task_struct *p)
156 {
157 struct autogroup *ag = autogroup_create();
158
159 autogroup_move_group(p, ag);
160 /* drop extra reference added by autogroup_create() */
161 autogroup_kref_put(ag);
162 }
163 EXPORT_SYMBOL(sched_autogroup_create_attach);
164
165 /* Cannot be called under siglock. Currently has no users */
sched_autogroup_detach(struct task_struct * p)166 void sched_autogroup_detach(struct task_struct *p)
167 {
168 autogroup_move_group(p, &autogroup_default);
169 }
170 EXPORT_SYMBOL(sched_autogroup_detach);
171
sched_autogroup_fork(struct signal_struct * sig)172 void sched_autogroup_fork(struct signal_struct *sig)
173 {
174 sig->autogroup = autogroup_task_get(current);
175 }
176
sched_autogroup_exit(struct signal_struct * sig)177 void sched_autogroup_exit(struct signal_struct *sig)
178 {
179 autogroup_kref_put(sig->autogroup);
180 }
181
setup_autogroup(char * str)182 static int __init setup_autogroup(char *str)
183 {
184 sysctl_sched_autogroup_enabled = 0;
185
186 return 1;
187 }
188
189 __setup("noautogroup", setup_autogroup);
190
191 #ifdef CONFIG_PROC_FS
192
proc_sched_autogroup_set_nice(struct task_struct * p,int nice)193 int proc_sched_autogroup_set_nice(struct task_struct *p, int nice)
194 {
195 static unsigned long next = INITIAL_JIFFIES;
196 struct autogroup *ag;
197 int err;
198
199 if (nice < MIN_NICE || nice > MAX_NICE)
200 return -EINVAL;
201
202 err = security_task_setnice(current, nice);
203 if (err)
204 return err;
205
206 if (nice < 0 && !can_nice(current, nice))
207 return -EPERM;
208
209 /* this is a heavy operation taking global locks.. */
210 if (!capable(CAP_SYS_ADMIN) && time_before(jiffies, next))
211 return -EAGAIN;
212
213 next = HZ / 10 + jiffies;
214 ag = autogroup_task_get(p);
215
216 down_write(&ag->lock);
217 err = sched_group_set_shares(ag->tg, prio_to_weight[nice + 20]);
218 if (!err)
219 ag->nice = nice;
220 up_write(&ag->lock);
221
222 autogroup_kref_put(ag);
223
224 return err;
225 }
226
proc_sched_autogroup_show_task(struct task_struct * p,struct seq_file * m)227 void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m)
228 {
229 struct autogroup *ag = autogroup_task_get(p);
230
231 if (!task_group_is_autogroup(ag->tg))
232 goto out;
233
234 down_read(&ag->lock);
235 seq_printf(m, "/autogroup-%ld nice %d\n", ag->id, ag->nice);
236 up_read(&ag->lock);
237
238 out:
239 autogroup_kref_put(ag);
240 }
241 #endif /* CONFIG_PROC_FS */
242
243 #ifdef CONFIG_SCHED_DEBUG
autogroup_path(struct task_group * tg,char * buf,int buflen)244 int autogroup_path(struct task_group *tg, char *buf, int buflen)
245 {
246 if (!task_group_is_autogroup(tg))
247 return 0;
248
249 return snprintf(buf, buflen, "%s-%ld", "/autogroup", tg->autogroup->id);
250 }
251 #endif /* CONFIG_SCHED_DEBUG */
252
253 #endif /* CONFIG_SCHED_AUTOGROUP */
254