1 /* $NetBSD: busypage.c,v 1.8 2020/03/17 18:31:39 ad Exp $ */
2
3 /*-
4 * Copyright (c) 2010 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND
17 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
18 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
23 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
24 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
25 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
26 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
27 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30 #include <sys/cdefs.h>
31 #if !defined(lint)
32 __RCSID("$NetBSD: busypage.c,v 1.8 2020/03/17 18:31:39 ad Exp $");
33 #endif /* !lint */
34
35 #include <sys/param.h>
36 #include <sys/condvar.h>
37 #include <sys/kthread.h>
38 #include <sys/mutex.h>
39 #include <sys/proc.h>
40
41 #include <uvm/uvm.h>
42
43 #include "kernspace.h"
44
45 static struct uvm_object *uobj;
46 static struct vm_page *testpg;
47 static kcondvar_t tcv;
48
49 static bool threadrun = false;
50
51 static void
thread(void * arg)52 thread(void *arg)
53 {
54
55 mutex_enter(&testpg->interlock);
56 threadrun = true;
57 cv_signal(&tcv);
58 mutex_exit(&testpg->interlock);
59
60 rw_enter(uobj->vmobjlock, RW_READER);
61 uvm_pagewait(testpg, uobj->vmobjlock, "tw");
62
63 kthread_exit(0);
64 }
65
66 void
rumptest_busypage()67 rumptest_busypage()
68 {
69 struct lwp *newl;
70 int rv;
71
72 cv_init(&tcv, "napina");
73
74 uobj = uao_create(1, 0);
75 rw_enter(uobj->vmobjlock, RW_WRITER);
76 testpg = uvm_pagealloc(uobj, 0, NULL, 0);
77 rw_exit(uobj->vmobjlock);
78 if (testpg == NULL)
79 panic("couldn't create vm page");
80
81 rv = kthread_create(PRI_NONE, KTHREAD_MUSTJOIN | KTHREAD_MPSAFE, NULL,
82 thread, NULL, &newl, "jointest");
83 if (rv)
84 panic("thread creation failed: %d", rv);
85
86 kpause("lolgic", false, mstohz(100), NULL);
87
88 mutex_enter(&testpg->interlock);
89 while (!threadrun)
90 cv_wait(&tcv, &testpg->interlock);
91 mutex_exit(&testpg->interlock);
92
93 rw_enter(uobj->vmobjlock, RW_WRITER);
94 uvm_page_unbusy(&testpg, 1);
95 rw_exit(uobj->vmobjlock);
96
97 rv = kthread_join(newl);
98 if (rv)
99 panic("thread join failed: %d", rv);
100
101 }
102