]>
Commit | Line | Data |
---|---|---|
b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
029632fb PZ |
2 | #include "sched.h" |
3 | ||
34f971f6 PZ |
4 | /* |
5 | * stop-task scheduling class. | |
6 | * | |
7 | * The stop task is the highest priority task in the system, it preempts | |
8 | * everything and will be preempted by nothing. | |
9 | * | |
10 | * See kernel/stop_machine.c | |
11 | */ | |
12 | ||
13 | #ifdef CONFIG_SMP | |
14 | static int | |
ac66f547 | 15 | select_task_rq_stop(struct task_struct *p, int cpu, int sd_flag, int flags) |
34f971f6 PZ |
16 | { |
17 | return task_cpu(p); /* stop tasks as never migrate */ | |
18 | } | |
19 | #endif /* CONFIG_SMP */ | |
20 | ||
21 | static void | |
22 | check_preempt_curr_stop(struct rq *rq, struct task_struct *p, int flags) | |
23 | { | |
1e5a7405 | 24 | /* we're never preempted */ |
34f971f6 PZ |
25 | } |
26 | ||
606dba2e | 27 | static struct task_struct * |
d8ac8971 | 28 | pick_next_task_stop(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) |
34f971f6 PZ |
29 | { |
30 | struct task_struct *stop = rq->stop; | |
31 | ||
da0c1e65 | 32 | if (!stop || !task_on_rq_queued(stop)) |
606dba2e | 33 | return NULL; |
34f971f6 | 34 | |
3f1d2a31 | 35 | put_prev_task(rq, prev); |
606dba2e PZ |
36 | |
37 | stop->se.exec_start = rq_clock_task(rq); | |
38 | ||
39 | return stop; | |
34f971f6 PZ |
40 | } |
41 | ||
42 | static void | |
43 | enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags) | |
44 | { | |
72465447 | 45 | add_nr_running(rq, 1); |
34f971f6 PZ |
46 | } |
47 | ||
48 | static void | |
49 | dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags) | |
50 | { | |
72465447 | 51 | sub_nr_running(rq, 1); |
34f971f6 PZ |
52 | } |
53 | ||
54 | static void yield_task_stop(struct rq *rq) | |
55 | { | |
56 | BUG(); /* the stop task should never yield, its pointless. */ | |
57 | } | |
58 | ||
59 | static void put_prev_task_stop(struct rq *rq, struct task_struct *prev) | |
60 | { | |
8f618968 MG |
61 | struct task_struct *curr = rq->curr; |
62 | u64 delta_exec; | |
63 | ||
78becc27 | 64 | delta_exec = rq_clock_task(rq) - curr->se.exec_start; |
8f618968 MG |
65 | if (unlikely((s64)delta_exec < 0)) |
66 | delta_exec = 0; | |
67 | ||
68 | schedstat_set(curr->se.statistics.exec_max, | |
69 | max(curr->se.statistics.exec_max, delta_exec)); | |
70 | ||
71 | curr->se.sum_exec_runtime += delta_exec; | |
72 | account_group_exec_runtime(curr, delta_exec); | |
73 | ||
78becc27 | 74 | curr->se.exec_start = rq_clock_task(rq); |
d2cc5ed6 | 75 | cgroup_account_cputime(curr, delta_exec); |
34f971f6 PZ |
76 | } |
77 | ||
78 | static void task_tick_stop(struct rq *rq, struct task_struct *curr, int queued) | |
79 | { | |
80 | } | |
81 | ||
82 | static void set_curr_task_stop(struct rq *rq) | |
83 | { | |
8f618968 MG |
84 | struct task_struct *stop = rq->stop; |
85 | ||
78becc27 | 86 | stop->se.exec_start = rq_clock_task(rq); |
34f971f6 PZ |
87 | } |
88 | ||
da7a735e | 89 | static void switched_to_stop(struct rq *rq, struct task_struct *p) |
34f971f6 PZ |
90 | { |
91 | BUG(); /* its impossible to change to this class */ | |
92 | } | |
93 | ||
da7a735e PZ |
94 | static void |
95 | prio_changed_stop(struct rq *rq, struct task_struct *p, int oldprio) | |
34f971f6 PZ |
96 | { |
97 | BUG(); /* how!?, what priority? */ | |
98 | } | |
99 | ||
100 | static unsigned int | |
101 | get_rr_interval_stop(struct rq *rq, struct task_struct *task) | |
102 | { | |
103 | return 0; | |
104 | } | |
105 | ||
90e362f4 TG |
106 | static void update_curr_stop(struct rq *rq) |
107 | { | |
108 | } | |
109 | ||
34f971f6 PZ |
110 | /* |
111 | * Simple, special scheduling class for the per-CPU stop tasks: | |
112 | */ | |
029632fb | 113 | const struct sched_class stop_sched_class = { |
aab03e05 | 114 | .next = &dl_sched_class, |
34f971f6 PZ |
115 | |
116 | .enqueue_task = enqueue_task_stop, | |
117 | .dequeue_task = dequeue_task_stop, | |
118 | .yield_task = yield_task_stop, | |
119 | ||
120 | .check_preempt_curr = check_preempt_curr_stop, | |
121 | ||
122 | .pick_next_task = pick_next_task_stop, | |
123 | .put_prev_task = put_prev_task_stop, | |
124 | ||
125 | #ifdef CONFIG_SMP | |
126 | .select_task_rq = select_task_rq_stop, | |
c5b28038 | 127 | .set_cpus_allowed = set_cpus_allowed_common, |
34f971f6 PZ |
128 | #endif |
129 | ||
130 | .set_curr_task = set_curr_task_stop, | |
131 | .task_tick = task_tick_stop, | |
132 | ||
133 | .get_rr_interval = get_rr_interval_stop, | |
134 | ||
135 | .prio_changed = prio_changed_stop, | |
136 | .switched_to = switched_to_stop, | |
90e362f4 | 137 | .update_curr = update_curr_stop, |
34f971f6 | 138 | }; |