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sys/compat/linuxkpi/common/src/linux_shrinker.c
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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"); | |||||
bz: I always wonder if we should document that fields are initialised by at least adding KASSERT()s? | |||||
Done Inline Actionsyou mean adding something like KASSERT(s->count_objects == NULL, ...) ? manu: you mean adding something like KASSERT(s->count_objects == NULL, ...) ?
Anyway yeah I think… | |||||
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; | |||||
Done Inline Actionsbatch is not needed until line 79; can it be initialised after the initial return? bz: batch is not needed until line 79; can it be initialised after the initial return? | |||||
Done Inline ActionsWill change. manu: Will change. | |||||
unsigned long can_free; | |||||
unsigned long batch; | |||||
unsigned long freeed = 0; | |||||
unsigned long ret; | |||||
can_free = s->count_objects(s, &sc); | |||||
if (can_free <= 0) | |||||
Done Inline ActionsNo { } needed. bz: No { } needed. | |||||
Done Inline Actionsprintf debugging leftover :) manu: printf debugging leftover :)
I'll change that. | |||||
return; | |||||
batch = s->batch ? s->batch : SHRINKER_BATCH; | |||||
while (freeed <= can_free) { | |||||
sc.nr_to_scan = batch; | |||||
ret = s->scan_objects(s, &sc); | |||||
if (ret == SHRINK_STOP) | |||||
break; | |||||
freeed += ret; | |||||
} | |||||
} | |||||
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) | |||||
{ | |||||
Done Inline ActionsLong line. bz: Long line. | |||||
Done Inline ActionsWill change. manu: Will change. | |||||
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); |
I always wonder if we should document that fields are initialised by at least adding KASSERT()s?
I guess I've been calling too many NULL function pointers lately elsewhere which were never initialised or checked on registration.