Root/mm/list_lru.c

1/*
2 * Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved.
3 * Authors: David Chinner and Glauber Costa
4 *
5 * Generic LRU infrastructure
6 */
7#include <linux/kernel.h>
8#include <linux/module.h>
9#include <linux/mm.h>
10#include <linux/list_lru.h>
11#include <linux/slab.h>
12
13bool list_lru_add(struct list_lru *lru, struct list_head *item)
14{
15    int nid = page_to_nid(virt_to_page(item));
16    struct list_lru_node *nlru = &lru->node[nid];
17
18    spin_lock(&nlru->lock);
19    WARN_ON_ONCE(nlru->nr_items < 0);
20    if (list_empty(item)) {
21        list_add_tail(item, &nlru->list);
22        if (nlru->nr_items++ == 0)
23            node_set(nid, lru->active_nodes);
24        spin_unlock(&nlru->lock);
25        return true;
26    }
27    spin_unlock(&nlru->lock);
28    return false;
29}
30EXPORT_SYMBOL_GPL(list_lru_add);
31
32bool list_lru_del(struct list_lru *lru, struct list_head *item)
33{
34    int nid = page_to_nid(virt_to_page(item));
35    struct list_lru_node *nlru = &lru->node[nid];
36
37    spin_lock(&nlru->lock);
38    if (!list_empty(item)) {
39        list_del_init(item);
40        if (--nlru->nr_items == 0)
41            node_clear(nid, lru->active_nodes);
42        WARN_ON_ONCE(nlru->nr_items < 0);
43        spin_unlock(&nlru->lock);
44        return true;
45    }
46    spin_unlock(&nlru->lock);
47    return false;
48}
49EXPORT_SYMBOL_GPL(list_lru_del);
50
51unsigned long
52list_lru_count_node(struct list_lru *lru, int nid)
53{
54    unsigned long count = 0;
55    struct list_lru_node *nlru = &lru->node[nid];
56
57    spin_lock(&nlru->lock);
58    WARN_ON_ONCE(nlru->nr_items < 0);
59    count += nlru->nr_items;
60    spin_unlock(&nlru->lock);
61
62    return count;
63}
64EXPORT_SYMBOL_GPL(list_lru_count_node);
65
66unsigned long
67list_lru_walk_node(struct list_lru *lru, int nid, list_lru_walk_cb isolate,
68           void *cb_arg, unsigned long *nr_to_walk)
69{
70
71    struct list_lru_node *nlru = &lru->node[nid];
72    struct list_head *item, *n;
73    unsigned long isolated = 0;
74
75    spin_lock(&nlru->lock);
76restart:
77    list_for_each_safe(item, n, &nlru->list) {
78        enum lru_status ret;
79
80        /*
81         * decrement nr_to_walk first so that we don't livelock if we
82         * get stuck on large numbesr of LRU_RETRY items
83         */
84        if (!*nr_to_walk)
85            break;
86        --*nr_to_walk;
87
88        ret = isolate(item, &nlru->lock, cb_arg);
89        switch (ret) {
90        case LRU_REMOVED:
91            if (--nlru->nr_items == 0)
92                node_clear(nid, lru->active_nodes);
93            WARN_ON_ONCE(nlru->nr_items < 0);
94            isolated++;
95            break;
96        case LRU_ROTATE:
97            list_move_tail(item, &nlru->list);
98            break;
99        case LRU_SKIP:
100            break;
101        case LRU_RETRY:
102            /*
103             * The lru lock has been dropped, our list traversal is
104             * now invalid and so we have to restart from scratch.
105             */
106            goto restart;
107        default:
108            BUG();
109        }
110    }
111
112    spin_unlock(&nlru->lock);
113    return isolated;
114}
115EXPORT_SYMBOL_GPL(list_lru_walk_node);
116
117int list_lru_init(struct list_lru *lru)
118{
119    int i;
120    size_t size = sizeof(*lru->node) * nr_node_ids;
121
122    lru->node = kzalloc(size, GFP_KERNEL);
123    if (!lru->node)
124        return -ENOMEM;
125
126    nodes_clear(lru->active_nodes);
127    for (i = 0; i < nr_node_ids; i++) {
128        spin_lock_init(&lru->node[i].lock);
129        INIT_LIST_HEAD(&lru->node[i].list);
130        lru->node[i].nr_items = 0;
131    }
132    return 0;
133}
134EXPORT_SYMBOL_GPL(list_lru_init);
135
136void list_lru_destroy(struct list_lru *lru)
137{
138    kfree(lru->node);
139}
140EXPORT_SYMBOL_GPL(list_lru_destroy);
141

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