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/* $NetBSD: linux_stop_machine.c,v 1.4 2022/04/09 23:38:33 riastradh Exp $ */
/*-
* Copyright (c) 2018 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Taylor R. Campbell.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: linux_stop_machine.c,v 1.4 2022/04/09 23:38:33 riastradh Exp $");
#include <sys/mutex.h> /* XXX work around cycle x86/mutex.h<->x86/intr.h */
#include <sys/atomic.h>
#include <sys/intr.h>
#include <sys/lock.h>
#include <sys/systm.h>
#include <sys/xcall.h>
#include <linux/stop_machine.h>
struct stop_machine {
int (*callback)(void *);
void *cookie;
volatile unsigned ncpu;
volatile bool done;
};
static void
stop_machine_xcall(void *a, void *b)
{
struct stop_machine *S = a;
int s;
/* Block all activity on this CPU. */
s = splhigh();
/* Note that we're ready, and see whether we're the chosen one. */
membar_release();
if (atomic_dec_uint_nv(&S->ncpu) != 0) {
while (!atomic_load_acquire(&S->done))
SPINLOCK_BACKOFF_HOOK;
goto out;
}
membar_acquire();
/* It's time. Call the callback. */
S->callback(S->cookie);
/* Notify everyone else that we're done. */
atomic_store_release(&S->done, true);
/* Allow activity again. */
out: splx(s);
}
void
stop_machine(int (*callback)(void *), void *cookie, const struct kcpuset *cpus)
{
struct stop_machine stop, *S = &stop;
KASSERT(cpus == NULL); /* not implemented */
S->callback = callback;
S->cookie = cookie;
S->ncpu = ncpu; /* XXX cpu hotplug */
S->done = false;
xc_wait(xc_broadcast(0, stop_machine_xcall, &S, NULL));
}
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