1 /* $NetBSD: linux_stop_machine.c,v 1.1 2021/12/19 01:34:57 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 1.1 2021/12/19 01:34:57 riastradh Exp $"); 34 35 #include <sys/atomic.h> 36 #include <sys/intr.h> 37 #include <sys/lock.h> 38 #include <sys/systm.h> 39 #include <sys/xcall.h> 40 41 #include <linux/stop_machine.h> 42 43 struct stop_machine { 44 int (*callback)(void *); 45 void *cookie; 46 volatile unsigned ncpu; 47 volatile bool done; 48 }; 49 50 static void 51 stop_machine_xcall(void *a, void *b) 52 { 53 struct stop_machine *S = a; 54 int s; 55 56 /* Block all activity on this CPU. */ 57 s = splhigh(); 58 59 /* Note that we're ready, and see whether we're the chosen one. */ 60 if (atomic_dec_uint_nv(&S->ncpu) != 0) { 61 /* Not the chosen one. Wait until done. */ 62 while (!S->done) 63 SPINLOCK_BACKOFF_HOOK; 64 goto out; 65 } 66 67 /* It's time. Call the callback. */ 68 S->callback(S->cookie); 69 70 /* Notify everyone else that we're done. */ 71 S->done = true; 72 73 /* Allow activity again. */ 74 out: splx(s); 75 } 76 77 void 78 stop_machine(int (*callback)(void *), void *cookie, const struct kcpuset *cpus) 79 { 80 struct stop_machine stop, *S = &stop; 81 82 KASSERT(cpus == NULL); /* not implemented */ 83 84 S->callback = callback; 85 S->cookie = cookie; 86 S->ncpu = ncpu; /* XXX cpu hotplug */ 87 S->done = false; 88 89 xc_wait(xc_broadcast(0, stop_machine_xcall, &S, NULL)); 90 } 91