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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 | { | |
953bfcd1 | 37 | inc_nr_running(rq); |
34f971f6 PZ |
38 | } |
39 | ||
40 | static void | |
41 | dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags) | |
42 | { | |
953bfcd1 | 43 | dec_nr_running(rq); |
34f971f6 PZ |
44 | } |
45 | ||
46 | static void yield_task_stop(struct rq *rq) | |
47 | { | |
48 | BUG(); /* the stop task should never yield, its pointless. */ | |
49 | } | |
50 | ||
51 | static void put_prev_task_stop(struct rq *rq, struct task_struct *prev) | |
52 | { | |
53 | } | |
54 | ||
55 | static void task_tick_stop(struct rq *rq, struct task_struct *curr, int queued) | |
56 | { | |
57 | } | |
58 | ||
59 | static void set_curr_task_stop(struct rq *rq) | |
60 | { | |
61 | } | |
62 | ||
da7a735e | 63 | static void switched_to_stop(struct rq *rq, struct task_struct *p) |
34f971f6 PZ |
64 | { |
65 | BUG(); /* its impossible to change to this class */ | |
66 | } | |
67 | ||
da7a735e PZ |
68 | static void |
69 | prio_changed_stop(struct rq *rq, struct task_struct *p, int oldprio) | |
34f971f6 PZ |
70 | { |
71 | BUG(); /* how!?, what priority? */ | |
72 | } | |
73 | ||
74 | static unsigned int | |
75 | get_rr_interval_stop(struct rq *rq, struct task_struct *task) | |
76 | { | |
77 | return 0; | |
78 | } | |
79 | ||
80 | /* | |
81 | * Simple, special scheduling class for the per-CPU stop tasks: | |
82 | */ | |
83 | static const struct sched_class stop_sched_class = { | |
84 | .next = &rt_sched_class, | |
85 | ||
86 | .enqueue_task = enqueue_task_stop, | |
87 | .dequeue_task = dequeue_task_stop, | |
88 | .yield_task = yield_task_stop, | |
89 | ||
90 | .check_preempt_curr = check_preempt_curr_stop, | |
91 | ||
92 | .pick_next_task = pick_next_task_stop, | |
93 | .put_prev_task = put_prev_task_stop, | |
94 | ||
95 | #ifdef CONFIG_SMP | |
96 | .select_task_rq = select_task_rq_stop, | |
97 | #endif | |
98 | ||
99 | .set_curr_task = set_curr_task_stop, | |
100 | .task_tick = task_tick_stop, | |
101 | ||
102 | .get_rr_interval = get_rr_interval_stop, | |
103 | ||
104 | .prio_changed = prio_changed_stop, | |
105 | .switched_to = switched_to_stop, | |
34f971f6 | 106 | }; |