1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
|
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Sat, 27 May 2017 19:02:06 +0200
Subject: kernel/sched/core: add migrate_disable()
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.2/older/patches-5.2.9-rt3.tar.xz
---
include/linux/preempt.h | 23 ++++++++
include/linux/sched.h | 7 ++
include/linux/smp.h | 3 +
kernel/sched/core.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++-
kernel/sched/debug.c | 4 +
5 files changed, 164 insertions(+), 2 deletions(-)
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -191,6 +191,22 @@ do { \
#define preemptible() (preempt_count() == 0 && !irqs_disabled())
+#ifdef CONFIG_SMP
+
+extern void migrate_disable(void);
+extern void migrate_enable(void);
+
+int __migrate_disabled(struct task_struct *p);
+
+#else
+#define migrate_disable() barrier()
+#define migrate_enable() barrier()
+static inline int __migrate_disabled(struct task_struct *p)
+{
+ return 0;
+}
+#endif
+
#ifdef CONFIG_PREEMPT
#define preempt_enable() \
do { \
@@ -259,6 +275,13 @@ do { \
#define preempt_enable_notrace() barrier()
#define preemptible() 0
+#define migrate_disable() barrier()
+#define migrate_enable() barrier()
+
+static inline int __migrate_disabled(struct task_struct *p)
+{
+ return 0;
+}
#endif /* CONFIG_PREEMPT_COUNT */
#ifdef MODULE
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -653,6 +653,13 @@ struct task_struct {
int nr_cpus_allowed;
const cpumask_t *cpus_ptr;
cpumask_t cpus_mask;
+#if defined(CONFIG_PREEMPT_COUNT) && defined(CONFIG_SMP)
+ int migrate_disable;
+ int migrate_disable_update;
+# ifdef CONFIG_SCHED_DEBUG
+ int migrate_disable_atomic;
+# endif
+#endif
#ifdef CONFIG_PREEMPT_RCU
int rcu_read_lock_nesting;
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -206,6 +206,9 @@ static inline int get_boot_cpu_id(void)
#define get_cpu() ({ preempt_disable(); smp_processor_id(); })
#define put_cpu() preempt_enable()
+#define get_cpu_light() ({ migrate_disable(); smp_processor_id(); })
+#define put_cpu_light() migrate_enable()
+
/*
* Callback to arch code if there's nosmp or maxcpus=0 on the
* boot command line:
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1060,7 +1060,15 @@ void set_cpus_allowed_common(struct task
p->nr_cpus_allowed = cpumask_weight(new_mask);
}
-void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
+#if defined(CONFIG_PREEMPT_COUNT) && defined(CONFIG_SMP)
+int __migrate_disabled(struct task_struct *p)
+{
+ return p->migrate_disable;
+}
+#endif
+
+static void __do_set_cpus_allowed_tail(struct task_struct *p,
+ const struct cpumask *new_mask)
{
struct rq *rq = task_rq(p);
bool queued, running;
@@ -1089,6 +1097,20 @@ void do_set_cpus_allowed(struct task_str
set_curr_task(rq, p);
}
+void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
+{
+#if defined(CONFIG_PREEMPT_COUNT) && defined(CONFIG_SMP)
+ if (__migrate_disabled(p)) {
+ lockdep_assert_held(&p->pi_lock);
+
+ cpumask_copy(&p->cpus_mask, new_mask);
+ p->migrate_disable_update = 1;
+ return;
+ }
+#endif
+ __do_set_cpus_allowed_tail(p, new_mask);
+}
+
/*
* Change a given task's CPU affinity. Migrate the thread to a
* proper CPU and schedule it away if the CPU it's executing on
@@ -1147,9 +1169,16 @@ static int __set_cpus_allowed_ptr(struct
}
/* Can the task run on the task's current CPU? If so, we're done */
- if (cpumask_test_cpu(task_cpu(p), new_mask))
+ if (cpumask_test_cpu(task_cpu(p), new_mask) || __migrate_disabled(p))
goto out;
+#if defined(CONFIG_PREEMPT_COUNT) && defined(CONFIG_SMP)
+ if (__migrate_disabled(p)) {
+ p->migrate_disable_update = 1;
+ goto out;
+ }
+#endif
+
dest_cpu = cpumask_any_and(cpu_valid_mask, new_mask);
if (task_running(rq, p) || p->state == TASK_WAKING) {
struct migration_arg arg = { p, dest_cpu };
@@ -7086,3 +7115,99 @@ const u32 sched_prio_to_wmult[40] = {
};
#undef CREATE_TRACE_POINTS
+
+#if defined(CONFIG_PREEMPT_COUNT) && defined(CONFIG_SMP)
+
+void migrate_disable(void)
+{
+ struct task_struct *p = current;
+
+ if (in_atomic() || irqs_disabled()) {
+#ifdef CONFIG_SCHED_DEBUG
+ p->migrate_disable_atomic++;
+#endif
+ return;
+ }
+#ifdef CONFIG_SCHED_DEBUG
+ WARN_ON_ONCE(p->migrate_disable_atomic);
+#endif
+
+ if (p->migrate_disable) {
+ p->migrate_disable++;
+ return;
+ }
+
+ preempt_disable();
+ p->migrate_disable = 1;
+
+ p->cpus_ptr = cpumask_of(smp_processor_id());
+ p->nr_cpus_allowed = 1;
+
+ preempt_enable();
+}
+EXPORT_SYMBOL(migrate_disable);
+
+void migrate_enable(void)
+{
+ struct task_struct *p = current;
+
+ if (in_atomic() || irqs_disabled()) {
+#ifdef CONFIG_SCHED_DEBUG
+ p->migrate_disable_atomic--;
+#endif
+ return;
+ }
+
+#ifdef CONFIG_SCHED_DEBUG
+ WARN_ON_ONCE(p->migrate_disable_atomic);
+#endif
+
+ WARN_ON_ONCE(p->migrate_disable <= 0);
+ if (p->migrate_disable > 1) {
+ p->migrate_disable--;
+ return;
+ }
+
+ preempt_disable();
+
+ p->cpus_ptr = &p->cpus_mask;
+ p->nr_cpus_allowed = cpumask_weight(&p->cpus_mask);
+ p->migrate_disable = 0;
+
+ if (p->migrate_disable_update) {
+ struct rq *rq;
+ struct rq_flags rf;
+
+ rq = task_rq_lock(p, &rf);
+ update_rq_clock(rq);
+
+ __do_set_cpus_allowed_tail(p, &p->cpus_mask);
+ task_rq_unlock(rq, p, &rf);
+
+ p->migrate_disable_update = 0;
+
+ WARN_ON(smp_processor_id() != task_cpu(p));
+ if (!cpumask_test_cpu(task_cpu(p), &p->cpus_mask)) {
+ const struct cpumask *cpu_valid_mask = cpu_active_mask;
+ struct migration_arg arg;
+ unsigned int dest_cpu;
+
+ if (p->flags & PF_KTHREAD) {
+ /*
+ * Kernel threads are allowed on online && !active CPUs
+ */
+ cpu_valid_mask = cpu_online_mask;
+ }
+ dest_cpu = cpumask_any_and(cpu_valid_mask, &p->cpus_mask);
+ arg.task = p;
+ arg.dest_cpu = dest_cpu;
+
+ preempt_enable();
+ stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
+ return;
+ }
+ }
+ preempt_enable();
+}
+EXPORT_SYMBOL(migrate_enable);
+#endif
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -979,6 +979,10 @@ void proc_sched_show_task(struct task_st
P(dl.runtime);
P(dl.deadline);
}
+#if defined(CONFIG_PREEMPT_COUNT) && defined(CONFIG_SMP)
+ P(migrate_disable);
+#endif
+ P(nr_cpus_allowed);
#undef PN_SCHEDSTAT
#undef PN
#undef __PN
|
