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5091faa4 MG |
1 | #ifdef CONFIG_SCHED_AUTOGROUP |
2 | ||
029632fb PZ |
3 | #include "sched.h" |
4 | ||
5091faa4 MG |
5 | #include <linux/proc_fs.h> |
6 | #include <linux/seq_file.h> | |
7 | #include <linux/kallsyms.h> | |
8 | #include <linux/utsname.h> | |
029632fb PZ |
9 | #include <linux/security.h> |
10 | #include <linux/export.h> | |
5091faa4 MG |
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 | ||
029632fb | 16 | void __init autogroup_init(struct task_struct *init_task) |
5091faa4 | 17 | { |
07e06b01 | 18 | autogroup_default.tg = &root_task_group; |
5091faa4 MG |
19 | kref_init(&autogroup_default.kref); |
20 | init_rwsem(&autogroup_default.lock); | |
21 | init_task->signal->autogroup = &autogroup_default; | |
22 | } | |
23 | ||
029632fb | 24 | void autogroup_free(struct task_group *tg) |
5091faa4 MG |
25 | { |
26 | kfree(tg->autogroup); | |
27 | } | |
28 | ||
29 | static inline void autogroup_destroy(struct kref *kref) | |
30 | { | |
31 | struct autogroup *ag = container_of(kref, struct autogroup, kref); | |
32 | ||
f4493771 MG |
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 | |
5091faa4 MG |
38 | sched_destroy_group(ag->tg); |
39 | } | |
40 | ||
41 | static inline void autogroup_kref_put(struct autogroup *ag) | |
42 | { | |
43 | kref_put(&ag->kref, autogroup_destroy); | |
44 | } | |
45 | ||
46 | static inline struct autogroup *autogroup_kref_get(struct autogroup *ag) | |
47 | { | |
48 | kref_get(&ag->kref); | |
49 | return ag; | |
50 | } | |
51 | ||
4f821987 MG |
52 | static inline struct autogroup *autogroup_task_get(struct task_struct *p) |
53 | { | |
54 | struct autogroup *ag; | |
55 | unsigned long flags; | |
56 | ||
57 | if (!lock_task_sighand(p, &flags)) | |
58 | return autogroup_kref_get(&autogroup_default); | |
59 | ||
60 | ag = autogroup_kref_get(p->signal->autogroup); | |
61 | unlock_task_sighand(p, &flags); | |
62 | ||
63 | return ag; | |
64 | } | |
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 | ||
029632fb | 111 | bool task_wants_autogroup(struct task_struct *p, struct task_group *tg) |
5091faa4 | 112 | { |
5258f386 MG |
113 | if (!sysctl_sched_autogroup_enabled) |
114 | return false; | |
115 | ||
5091faa4 MG |
116 | if (tg != &root_task_group) |
117 | return false; | |
118 | ||
119 | if (p->sched_class != &fair_sched_class) | |
120 | return false; | |
121 | ||
122 | /* | |
123 | * We can only assume the task group can't go away on us if | |
124 | * autogroup_move_group() can see us on ->thread_group list. | |
125 | */ | |
126 | if (p->flags & PF_EXITING) | |
127 | return false; | |
128 | ||
129 | return true; | |
130 | } | |
131 | ||
5091faa4 MG |
132 | static void |
133 | autogroup_move_group(struct task_struct *p, struct autogroup *ag) | |
134 | { | |
135 | struct autogroup *prev; | |
136 | struct task_struct *t; | |
137 | unsigned long flags; | |
138 | ||
139 | BUG_ON(!lock_task_sighand(p, &flags)); | |
140 | ||
141 | prev = p->signal->autogroup; | |
142 | if (prev == ag) { | |
143 | unlock_task_sighand(p, &flags); | |
144 | return; | |
145 | } | |
146 | ||
147 | p->signal->autogroup = autogroup_kref_get(ag); | |
148 | ||
149 | t = p; | |
150 | do { | |
151 | sched_move_task(t); | |
152 | } while_each_thread(p, t); | |
153 | ||
154 | unlock_task_sighand(p, &flags); | |
155 | autogroup_kref_put(prev); | |
156 | } | |
157 | ||
158 | /* Allocates GFP_KERNEL, cannot be called under any spinlock */ | |
159 | void sched_autogroup_create_attach(struct task_struct *p) | |
160 | { | |
5258f386 | 161 | struct autogroup *ag; |
5091faa4 | 162 | |
5258f386 MG |
163 | if (!sysctl_sched_autogroup_enabled) |
164 | return; | |
165 | ag = autogroup_create(); | |
5091faa4 | 166 | autogroup_move_group(p, ag); |
25985edc | 167 | /* drop extra reference added by autogroup_create() */ |
5091faa4 MG |
168 | autogroup_kref_put(ag); |
169 | } | |
170 | EXPORT_SYMBOL(sched_autogroup_create_attach); | |
171 | ||
172 | /* Cannot be called under siglock. Currently has no users */ | |
173 | void sched_autogroup_detach(struct task_struct *p) | |
174 | { | |
175 | autogroup_move_group(p, &autogroup_default); | |
176 | } | |
177 | EXPORT_SYMBOL(sched_autogroup_detach); | |
178 | ||
179 | void sched_autogroup_fork(struct signal_struct *sig) | |
180 | { | |
5258f386 MG |
181 | if (!sysctl_sched_autogroup_enabled) |
182 | return; | |
4f821987 | 183 | sig->autogroup = autogroup_task_get(current); |
5091faa4 MG |
184 | } |
185 | ||
186 | void sched_autogroup_exit(struct signal_struct *sig) | |
187 | { | |
5258f386 MG |
188 | if (!sysctl_sched_autogroup_enabled) |
189 | return; | |
5091faa4 MG |
190 | autogroup_kref_put(sig->autogroup); |
191 | } | |
192 | ||
193 | static int __init setup_autogroup(char *str) | |
194 | { | |
195 | sysctl_sched_autogroup_enabled = 0; | |
196 | ||
197 | return 1; | |
198 | } | |
199 | ||
200 | __setup("noautogroup", setup_autogroup); | |
201 | ||
5091faa4 | 202 | #ifdef CONFIG_SCHED_DEBUG |
029632fb | 203 | int autogroup_path(struct task_group *tg, char *buf, int buflen) |
5091faa4 | 204 | { |
511f67a5 | 205 | if (!task_group_is_autogroup(tg)) |
8ecedd7a BR |
206 | return 0; |
207 | ||
5091faa4 MG |
208 | return snprintf(buf, buflen, "%s-%ld", "/autogroup", tg->autogroup->id); |
209 | } | |
210 | #endif /* CONFIG_SCHED_DEBUG */ | |
211 | ||
212 | #endif /* CONFIG_SCHED_AUTOGROUP */ |