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
|
/* litmus/sync.c - Support for synchronous and asynchronous task system releases.
*
*
*/
#include <asm/atomic.h>
#include <asm/uaccess.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/sched.h>
#include <linux/completion.h>
#include <litmus/litmus.h>
#include <litmus/sched_plugin.h>
#include <litmus/jobs.h>
#include <litmus/sched_trace.h>
struct ts_release_wait {
struct list_head list;
struct completion completion;
lt_t ts_release_time;
};
#define DECLARE_TS_RELEASE_WAIT(symb) \
struct ts_release_wait symb = \
{ \
LIST_HEAD_INIT(symb.list), \
COMPLETION_INITIALIZER_ONSTACK(symb.completion), \
0 \
}
static LIST_HEAD(task_release_list);
static DEFINE_MUTEX(task_release_lock);
static long do_wait_for_ts_release(void)
{
DECLARE_TS_RELEASE_WAIT(wait);
long ret = -ERESTARTSYS;
if (mutex_lock_interruptible(&task_release_lock))
goto out;
list_add(&wait.list, &task_release_list);
mutex_unlock(&task_release_lock);
/* We are enqueued, now we wait for someone to wake us up. */
ret = wait_for_completion_interruptible(&wait.completion);
if (!ret) {
/* Setting this flag before releasing ensures that this CPU
* will be the next CPU to requeue the task on a ready or
* release queue. Cleared by prepare_for_next_period()
*/
tsk_rt(current)->dont_requeue = 1;
/* Completion succeeded, setup release time. complete_job()
* will indirectly cause the period to be added to the next
* release time, so subtract it here. */
litmus->release_at(current, wait.ts_release_time
+ current->rt_param.task_params.phase
- current->rt_param.task_params.period);
/* Advance to next job --- when complete_job() returns, the
* first job has been released. Since we patched up the release
* time, this occurs when all tasks synchronously release their
* first job.*/
ret = complete_job();
} else {
/* We were interrupted, must cleanup list. */
mutex_lock(&task_release_lock);
if (!wait.completion.done)
list_del(&wait.list);
mutex_unlock(&task_release_lock);
}
out:
return ret;
}
int count_tasks_waiting_for_release(void)
{
int task_count = 0;
struct list_head *pos;
mutex_lock(&task_release_lock);
list_for_each(pos, &task_release_list) {
task_count++;
}
mutex_unlock(&task_release_lock);
return task_count;
}
static long do_release_ts(lt_t start)
{
long task_count = 0;
struct list_head *pos, *safe;
struct ts_release_wait *wait;
if (mutex_lock_interruptible(&task_release_lock)) {
task_count = -ERESTARTSYS;
goto out;
}
TRACE("<<<<<< synchronous task system release >>>>>>\n");
sched_trace_sys_release(&start);
task_count = 0;
list_for_each_safe(pos, safe, &task_release_list) {
wait = (struct ts_release_wait*)
list_entry(pos, struct ts_release_wait, list);
task_count++;
wait->ts_release_time = start;
complete(&wait->completion);
}
/* clear stale list */
INIT_LIST_HEAD(&task_release_list);
mutex_unlock(&task_release_lock);
out:
return task_count;
}
asmlinkage long sys_wait_for_ts_release(void)
{
long ret = -EPERM;
struct task_struct *t = current;
if (is_realtime(t))
ret = do_wait_for_ts_release();
return ret;
}
#define ONE_MS 1000000
asmlinkage long sys_release_ts(lt_t __user *__delay)
{
long ret;
lt_t delay;
lt_t start_time;
/* FIXME: check capabilities... */
ret = copy_from_user(&delay, __delay, sizeof(delay));
if (ret == 0) {
/* round up to next larger integral millisecond */
start_time = litmus_clock();
do_div(start_time, ONE_MS);
start_time *= ONE_MS;
ret = do_release_ts(start_time + delay);
}
return ret;
}
|
