kern_kthread.c revision 1.27 
1/*	$NetBSD: kern_kthread.c,v 1.27 2009/10/21 21:12:06 rmind Exp $	*/
2
3/*-
4 * Copyright (c) 1998, 1999, 2007, 2009 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
9 * NASA Ames Research Center, and by Andrew Doran.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32
33#include <sys/cdefs.h>
34__KERNEL_RCSID(0, "$NetBSD: kern_kthread.c,v 1.27 2009/10/21 21:12:06 rmind Exp $");
35
36#include <sys/param.h>
37#include <sys/systm.h>
38#include <sys/kernel.h>
39#include <sys/kthread.h>
40#include <sys/proc.h>
41#include <sys/sched.h>
42#include <sys/kmem.h>
43
44#include <uvm/uvm_extern.h>
45
46/*
47 * note that stdarg.h and the ansi style va_start macro is used for both
48 * ansi and traditional c complers.
49 * XXX: this requires that stdarg.h define: va_alist and va_dcl
50 */
51#include <machine/stdarg.h>
52
53/*
54 * Fork a kernel thread.  Any process can request this to be done.
55 */
56int
57kthread_create(pri_t pri, int flag, struct cpu_info *ci,
58	       void (*func)(void *), void *arg,
59	       lwp_t **lp, const char *fmt, ...)
60{
61	lwp_t *l;
62	vaddr_t uaddr;
63	int error;
64	va_list ap;
65	int lc;
66
67	uaddr = uvm_uarea_alloc();
68	if (uaddr == 0) {
69		return ENOMEM;
70	}
71	if ((flag & KTHREAD_TS) != 0) {
72		lc = SCHED_OTHER;
73	} else {
74		lc = SCHED_RR;
75	}
76	error = lwp_create(&lwp0, &proc0, uaddr, LWP_DETACHED, NULL,
77	    0, func, arg, &l, lc);
78	if (error) {
79		uvm_uarea_free(uaddr);
80		return error;
81	}
82	if (fmt != NULL) {
83		l->l_name = kmem_alloc(MAXCOMLEN, KM_SLEEP);
84		if (l->l_name == NULL) {
85			lwp_exit(l);
86			return ENOMEM;
87		}
88		va_start(ap, fmt);
89		vsnprintf(l->l_name, MAXCOMLEN, fmt, ap);
90		va_end(ap);
91	}
92
93	/*
94	 * Set parameters.
95	 */
96	if ((flag & KTHREAD_INTR) != 0) {
97		KASSERT((flag & KTHREAD_MPSAFE) != 0);
98	}
99
100	if (pri == PRI_NONE) {
101		if ((flag & KTHREAD_TS) != 0) {
102			/* Maximum user priority level. */
103			pri = MAXPRI_USER;
104		} else {
105			/* Minimum kernel priority level. */
106			pri = PRI_KTHREAD;
107		}
108	}
109	mutex_enter(proc0.p_lock);
110	lwp_lock(l);
111	l->l_priority = pri;
112	if (ci != NULL) {
113		if (ci != l->l_cpu) {
114			lwp_unlock_to(l, ci->ci_schedstate.spc_mutex);
115			lwp_lock(l);
116		}
117		l->l_pflag |= LP_BOUND;
118		l->l_cpu = ci;
119	}
120	if ((flag & KTHREAD_INTR) != 0)
121		l->l_pflag |= LP_INTR;
122	if ((flag & KTHREAD_MPSAFE) == 0)
123		l->l_pflag &= ~LP_MPSAFE;
124
125	/*
126	 * Set the new LWP running, unless the caller has requested
127	 * otherwise.
128	 */
129	if ((flag & KTHREAD_IDLE) == 0) {
130		l->l_stat = LSRUN;
131		sched_enqueue(l, false);
132		lwp_unlock(l);
133	} else
134		lwp_unlock_to(l, ci->ci_schedstate.spc_lwplock);
135
136	/*
137	 * The LWP is not created suspended or stopped and cannot be set
138	 * into those states later, so must be considered runnable.
139	 */
140	proc0.p_nrlwps++;
141	mutex_exit(proc0.p_lock);
142
143	/* All done! */
144	if (lp != NULL)
145		*lp = l;
146
147	return (0);
148}
149
150/*
151 * Cause a kernel thread to exit.  Assumes the exiting thread is the
152 * current context.
153 */
154void
155kthread_exit(int ecode)
156{
157	const char *name;
158	lwp_t *l = curlwp;
159
160	/* We can't do much with the exit code, so just report it. */
161	if (ecode != 0) {
162		if ((name = l->l_name) == NULL)
163			name = "unnamed";
164		printf("WARNING: kthread `%s' (%d) exits with status %d\n",
165		    name, l->l_lid, ecode);
166	}
167
168	/* And exit.. */
169	lwp_exit(l);
170
171	/*
172	 * XXX Fool the compiler.  Making exit1() __noreturn__ is a can
173	 * XXX of worms right now.
174	 */
175	for (;;)
176		;
177}
178
179/*
180 * Destroy an inactive kthread.  The kthread must be in the LSIDL state.
181 */
182void
183kthread_destroy(lwp_t *l)
184{
185
186	KASSERT((l->l_flag & LW_SYSTEM) != 0);
187	KASSERT(l->l_stat == LSIDL);
188
189	lwp_exit(l);
190}
191