blob: 1330d279f48ac8a3a5f8fcbe4ae79ade8ffee6d3 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* Deferred dmabuf freeing helper
*
* Copyright (C) 2020 Linaro, Ltd.
*
* Based on the ION page pool code
* Copyright (C) 2011 Google, Inc.
*/
#include <linux/freezer.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/sched/signal.h>
#include "deferred-free-helper.h"
static LIST_HEAD(free_list);
static size_t list_nr_pages;
wait_queue_head_t freelist_waitqueue;
struct task_struct *freelist_task;
static DEFINE_SPINLOCK(free_list_lock);
void deferred_free(struct deferred_freelist_item *item,
void (*free)(struct deferred_freelist_item*,
enum df_reason),
size_t nr_pages)
{
unsigned long flags;
INIT_LIST_HEAD(&item->list);
item->nr_pages = nr_pages;
item->free = free;
spin_lock_irqsave(&free_list_lock, flags);
list_add(&item->list, &free_list);
list_nr_pages += nr_pages;
spin_unlock_irqrestore(&free_list_lock, flags);
wake_up(&freelist_waitqueue);
}
EXPORT_SYMBOL_GPL(deferred_free);
static size_t free_one_item(enum df_reason reason)
{
unsigned long flags;
size_t nr_pages;
struct deferred_freelist_item *item;
spin_lock_irqsave(&free_list_lock, flags);
if (list_empty(&free_list)) {
spin_unlock_irqrestore(&free_list_lock, flags);
return 0;
}
item = list_first_entry(&free_list, struct deferred_freelist_item, list);
list_del(&item->list);
nr_pages = item->nr_pages;
list_nr_pages -= nr_pages;
spin_unlock_irqrestore(&free_list_lock, flags);
item->free(item, reason);
return nr_pages;
}
unsigned long get_freelist_nr_pages(void)
{
unsigned long nr_pages;
unsigned long flags;
spin_lock_irqsave(&free_list_lock, flags);
nr_pages = list_nr_pages;
spin_unlock_irqrestore(&free_list_lock, flags);
return nr_pages;
}
EXPORT_SYMBOL_GPL(get_freelist_nr_pages);
static unsigned long freelist_shrink_count(struct shrinker *shrinker,
struct shrink_control *sc)
{
return get_freelist_nr_pages();
}
static unsigned long freelist_shrink_scan(struct shrinker *shrinker,
struct shrink_control *sc)
{
unsigned long total_freed = 0;
if (sc->nr_to_scan == 0)
return 0;
while (total_freed < sc->nr_to_scan) {
size_t pages_freed = free_one_item(DF_UNDER_PRESSURE);
if (!pages_freed)
break;
total_freed += pages_freed;
}
return total_freed;
}
static struct shrinker freelist_shrinker = {
.count_objects = freelist_shrink_count,
.scan_objects = freelist_shrink_scan,
.seeks = DEFAULT_SEEKS,
.batch = 0,
};
static int deferred_free_thread(void *data)
{
while (true) {
wait_event_freezable(freelist_waitqueue,
get_freelist_nr_pages() > 0);
free_one_item(DF_NORMAL);
}
return 0;
}
static int deferred_freelist_init(void)
{
list_nr_pages = 0;
init_waitqueue_head(&freelist_waitqueue);
freelist_task = kthread_run(deferred_free_thread, NULL,
"%s", "dmabuf-deferred-free-worker");
if (IS_ERR(freelist_task)) {
pr_err("Creating thread for deferred free failed\n");
return -1;
}
sched_set_normal(freelist_task, 19);
return register_shrinker(&freelist_shrinker);
}
module_init(deferred_freelist_init);
MODULE_LICENSE("GPL v2");