1 /*
2 * Copyright (c) 2019 François Tigeot <ftigeot@wolfpond.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice unmodified, this list of conditions, and the following
10 * disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 #include <linux/kthread.h>
28 #include <linux/sched.h>
29 #include <linux/slab.h>
30
31 #include <sys/kthread.h>
32
33 /*
34 All Linux threads/processes have an associated task_struct
35 a kthread is a pure kernel thread without userland context
36 */
37
38 static void
linux_ktfn_wrapper(void * arg)39 linux_ktfn_wrapper(void *arg)
40 {
41 struct task_struct *task = arg;
42
43 task->kt_exitvalue = task->kt_fn(task->kt_fndata);
44 }
45
46 struct task_struct *
kthread_run(int (* lfn)(void *),void * data,const char * namefmt,...)47 kthread_run(int (*lfn)(void *), void *data, const char *namefmt, ...)
48 {
49 struct task_struct *task;
50 struct thread *td;
51 __va_list args;
52 int ret;
53
54 task = kzalloc(sizeof(*task), GFP_KERNEL);
55
56 __va_start(args, namefmt);
57 ret = kthread_alloc(linux_ktfn_wrapper, task, &td, namefmt, args);
58 __va_end(args);
59 if (ret) {
60 kfree(task);
61 return ERR_PTR(-ENOMEM);
62 }
63
64 task->dfly_td = td;
65 td->td_linux_task = task;
66
67 task->mm = NULL; /* kthreads have no userland address space */
68
69 task->kt_fn = lfn;
70 task->kt_fndata = data;
71 spin_init(&task->kt_spin, "tspin1");
72
73 /* Start the thread here */
74 lwkt_schedule(td);
75
76 return task;
77 }
78
79 #define KTHREAD_SHOULD_STOP 1
80 #define KTHREAD_SHOULD_PARK 2
81
82 bool
kthread_should_stop(void)83 kthread_should_stop(void)
84 {
85 return test_bit(KTHREAD_SHOULD_STOP, ¤t->kt_flags);
86 }
87
88 int
kthread_stop(struct task_struct * ts)89 kthread_stop(struct task_struct *ts)
90 {
91 set_bit(KTHREAD_SHOULD_STOP, &ts->kt_flags);
92
93 kthread_unpark(ts);
94 wake_up_process(ts);
95
96 /* XXX use a better mechanism to wait for the thread to finish running */
97 tsleep(kthread_stop, 0, "kstop", hz);
98 lwkt_free_thread(ts->dfly_td);
99
100 return ts->kt_exitvalue;
101 }
102
103 int
kthread_park(struct task_struct * ts)104 kthread_park(struct task_struct *ts)
105 {
106 set_bit(KTHREAD_SHOULD_PARK, &ts->kt_flags);
107 wake_up_process(ts);
108
109 return ts->kt_exitvalue;
110 }
111
112 void
kthread_unpark(struct task_struct * ts)113 kthread_unpark(struct task_struct *ts)
114 {
115 clear_bit(KTHREAD_SHOULD_PARK, &ts->kt_flags);
116 lwkt_schedule(ts->dfly_td);
117 wake_up_process(ts);
118 }
119
120 bool
kthread_should_park(void)121 kthread_should_park(void)
122 {
123 return test_bit(KTHREAD_SHOULD_PARK, ¤t->kt_flags);
124 }
125
126 void
kthread_parkme(void)127 kthread_parkme(void)
128 {
129 if (test_bit(KTHREAD_SHOULD_PARK, ¤t->kt_flags) == 0)
130 return;
131
132 lwkt_deschedule_self(curthread);
133 }
134