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/*-
* Copyright (c) 2020 Emmanuel Vadot <manu@FreeBSD.org>
*
* 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 AUTHOR 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 AUTHOR 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.
*
* $FreeBSD$
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/queue.h>
#include <sys/eventhandler.h>
#include <sys/mutex.h>
#include <linux/shrinker.h>
TAILQ_HEAD(, shrinker) lkpi_shrinkers = TAILQ_HEAD_INITIALIZER(lkpi_shrinkers);
static struct mtx mtx_shrinker;
int
linuxkpi_register_shrinker(struct shrinker *s)
{
KASSERT(s != NULL, ("NULL shrinker"));
KASSERT(s->count_objects != NULL, ("NULL shrinker"));
KASSERT(s->scan_objects != NULL, ("NULL shrinker"));
mtx_lock(&mtx_shrinker);
TAILQ_INSERT_TAIL(&lkpi_shrinkers, s, next);
mtx_unlock(&mtx_shrinker);
return (0);
}
void
linuxkpi_unregister_shrinker(struct shrinker *s)
{
mtx_lock(&mtx_shrinker);
TAILQ_REMOVE(&lkpi_shrinkers, s, next);
mtx_unlock(&mtx_shrinker);
}
#define SHRINKER_BATCH 512
static void
shrinker_shrink(struct shrinker *s)
{
struct shrink_control sc;
unsigned long can_free;
unsigned long batch;
unsigned long scanned = 0;
unsigned long ret;
can_free = s->count_objects(s, &sc);
if (can_free <= 0)
return;
batch = s->batch ? s->batch : SHRINKER_BATCH;
while (scanned <= can_free) {
sc.nr_to_scan = batch;
ret = s->scan_objects(s, &sc);
if (ret == SHRINK_STOP)
break;
scanned += batch;
}
}
static void
linuxkpi_vm_lowmem(void *arg __unused)
{
struct shrinker *s;
mtx_lock(&mtx_shrinker);
TAILQ_FOREACH(s, &lkpi_shrinkers, next) {
shrinker_shrink(s);
}
mtx_unlock(&mtx_shrinker);
}
static eventhandler_tag lowmem_tag;
static void
linuxkpi_sysinit_shrinker(void *arg __unused)
{
mtx_init(&mtx_shrinker, "lkpi-shrinker", NULL, MTX_DEF);
lowmem_tag = EVENTHANDLER_REGISTER(vm_lowmem, linuxkpi_vm_lowmem,
NULL, EVENTHANDLER_PRI_FIRST);
}
static void
linuxkpi_sysuninit_shrinker(void *arg __unused)
{
mtx_destroy(&mtx_shrinker);
EVENTHANDLER_DEREGISTER(vm_lowmem, lowmem_tag);
}
SYSINIT(linuxkpi_shrinker, SI_SUB_DRIVERS, SI_ORDER_ANY,
linuxkpi_sysinit_shrinker, NULL);
SYSUNINIT(linuxkpi_shrinker, SI_SUB_DRIVERS, SI_ORDER_ANY,
linuxkpi_sysuninit_shrinker, NULL);
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