Commit | Line | Data |
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34f971f6 PZ |
1 | /* |
2 | * stop-task scheduling class. | |
3 | * | |
4 | * The stop task is the highest priority task in the system, it preempts | |
5 | * everything and will be preempted by nothing. | |
6 | * | |
7 | * See kernel/stop_machine.c | |
8 | */ | |
9 | ||
10 | #ifdef CONFIG_SMP | |
11 | static int | |
7608dec2 | 12 | select_task_rq_stop(struct task_struct *p, int sd_flag, int flags) |
34f971f6 PZ |
13 | { |
14 | return task_cpu(p); /* stop tasks as never migrate */ | |
15 | } | |
16 | #endif /* CONFIG_SMP */ | |
17 | ||
18 | static void | |
19 | check_preempt_curr_stop(struct rq *rq, struct task_struct *p, int flags) | |
20 | { | |
1e5a7405 | 21 | /* we're never preempted */ |
34f971f6 PZ |
22 | } |
23 | ||
24 | static struct task_struct *pick_next_task_stop(struct rq *rq) | |
25 | { | |
26 | struct task_struct *stop = rq->stop; | |
27 | ||
fd2f4419 | 28 | if (stop && stop->on_rq) |
34f971f6 PZ |
29 | return stop; |
30 | ||
31 | return NULL; | |
32 | } | |
33 | ||
34 | static void | |
35 | enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags) | |
36 | { | |
37 | } | |
38 | ||
39 | static void | |
40 | dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags) | |
41 | { | |
42 | } | |
43 | ||
44 | static void yield_task_stop(struct rq *rq) | |
45 | { | |
46 | BUG(); /* the stop task should never yield, its pointless. */ | |
47 | } | |
48 | ||
49 | static void put_prev_task_stop(struct rq *rq, struct task_struct *prev) | |
50 | { | |
51 | } | |
52 | ||
53 | static void task_tick_stop(struct rq *rq, struct task_struct *curr, int queued) | |
54 | { | |
55 | } | |
56 | ||
57 | static void set_curr_task_stop(struct rq *rq) | |
58 | { | |
59 | } | |
60 | ||
da7a735e | 61 | static void switched_to_stop(struct rq *rq, struct task_struct *p) |
34f971f6 PZ |
62 | { |
63 | BUG(); /* its impossible to change to this class */ | |
64 | } | |
65 | ||
da7a735e PZ |
66 | static void |
67 | prio_changed_stop(struct rq *rq, struct task_struct *p, int oldprio) | |
34f971f6 PZ |
68 | { |
69 | BUG(); /* how!?, what priority? */ | |
70 | } | |
71 | ||
72 | static unsigned int | |
73 | get_rr_interval_stop(struct rq *rq, struct task_struct *task) | |
74 | { | |
75 | return 0; | |
76 | } | |
77 | ||
78 | /* | |
79 | * Simple, special scheduling class for the per-CPU stop tasks: | |
80 | */ | |
81 | static const struct sched_class stop_sched_class = { | |
82 | .next = &rt_sched_class, | |
83 | ||
84 | .enqueue_task = enqueue_task_stop, | |
85 | .dequeue_task = dequeue_task_stop, | |
86 | .yield_task = yield_task_stop, | |
87 | ||
88 | .check_preempt_curr = check_preempt_curr_stop, | |
89 | ||
90 | .pick_next_task = pick_next_task_stop, | |
91 | .put_prev_task = put_prev_task_stop, | |
92 | ||
93 | #ifdef CONFIG_SMP | |
94 | .select_task_rq = select_task_rq_stop, | |
95 | #endif | |
96 | ||
97 | .set_curr_task = set_curr_task_stop, | |
98 | .task_tick = task_tick_stop, | |
99 | ||
100 | .get_rr_interval = get_rr_interval_stop, | |
101 | ||
102 | .prio_changed = prio_changed_stop, | |
103 | .switched_to = switched_to_stop, | |
34f971f6 | 104 | }; |