linux_stop_machine.c revision 1.2 
1/*	$NetBSD: linux_stop_machine.c,v 1.2 2021/12/19 11:22:22 riastradh Exp $	*/
2
3/*-
4 * Copyright (c) 2018 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Taylor R. Campbell.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33__KERNEL_RCSID(0, "$NetBSD: linux_stop_machine.c,v 1.2 2021/12/19 11:22:22 riastradh Exp $");
34
35#include <sys/mutex.h> /* XXX work around cycle x86/mutex.h<->x86/intr.h */
36
37#include <sys/atomic.h>
38#include <sys/intr.h>
39#include <sys/lock.h>
40#include <sys/systm.h>
41#include <sys/xcall.h>
42
43#include <linux/stop_machine.h>
44
45struct stop_machine {
46	int			(*callback)(void *);
47	void			*cookie;
48	volatile unsigned	ncpu;
49	volatile bool		done;
50};
51
52static void
53stop_machine_xcall(void *a, void *b)
54{
55	struct stop_machine *S = a;
56	int s;
57
58	/* Block all activity on this CPU.  */
59	s = splhigh();
60
61	/* Note that we're ready, and see whether we're the chosen one.  */
62	if (atomic_dec_uint_nv(&S->ncpu) != 0) {
63		/* Not the chosen one.  Wait until done.  */
64		while (!S->done)
65			SPINLOCK_BACKOFF_HOOK;
66		goto out;
67	}
68
69	/* It's time.  Call the callback.  */
70	S->callback(S->cookie);
71
72	/* Notify everyone else that we're done.  */
73	S->done = true;
74
75	/* Allow activity again.  */
76out:	splx(s);
77}
78
79void
80stop_machine(int (*callback)(void *), void *cookie, const struct kcpuset *cpus)
81{
82	struct stop_machine stop, *S = &stop;
83
84	KASSERT(cpus == NULL);	/* not implemented */
85
86	S->callback = callback;
87	S->cookie = cookie;
88	S->ncpu = ncpu;		/* XXX cpu hotplug */
89	S->done = false;
90
91	xc_wait(xc_broadcast(0, stop_machine_xcall, &S, NULL));
92}
93