1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
|
/*
* Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved.
* Authors: David Chinner and Glauber Costa
*
* Generic LRU infrastructure
*/
#ifndef _LRU_LIST_H
#define _LRU_LIST_H
#include <linux/list.h>
#include <linux/nodemask.h>
/* list_lru_walk_cb has to always return one of those */
enum lru_status {
LRU_REMOVED, /* item removed from list */
LRU_ROTATE, /* item referenced, give another pass */
LRU_SKIP, /* item cannot be locked, skip */
LRU_RETRY, /* item not freeable. May drop the lock
internally, but has to return locked. */
};
struct list_lru_node {
spinlock_t lock;
struct list_head list;
/* kept as signed so we can catch imbalance bugs */
long nr_items;
} ____cacheline_aligned_in_smp;
struct list_lru {
/*
* Because we use a fixed-size array, this struct can be very big if
* MAX_NUMNODES is big. If this becomes a problem this is fixable by
* turning this into a pointer and dynamically allocating this to
* nr_node_ids. This quantity is firwmare-provided, and still would
* provide room for all nodes at the cost of a pointer lookup and an
* extra allocation. Because that allocation will most likely come from
* a different slab cache than the main structure holding this
* structure, we may very well fail.
*/
struct list_lru_node node[MAX_NUMNODES];
nodemask_t active_nodes;
};
int list_lru_init(struct list_lru *lru);
/**
* list_lru_add: add an element to the lru list's tail
* @list_lru: the lru pointer
* @item: the item to be added.
*
* If the element is already part of a list, this function returns doing
* nothing. Therefore the caller does not need to keep state about whether or
* not the element already belongs in the list and is allowed to lazy update
* it. Note however that this is valid for *a* list, not *this* list. If
* the caller organize itself in a way that elements can be in more than
* one type of list, it is up to the caller to fully remove the item from
* the previous list (with list_lru_del() for instance) before moving it
* to @list_lru
*
* Return value: true if the list was updated, false otherwise
*/
bool list_lru_add(struct list_lru *lru, struct list_head *item);
/**
* list_lru_del: delete an element to the lru list
* @list_lru: the lru pointer
* @item: the item to be deleted.
*
* This function works analogously as list_lru_add in terms of list
* manipulation. The comments about an element already pertaining to
* a list are also valid for list_lru_del.
*
* Return value: true if the list was updated, false otherwise
*/
bool list_lru_del(struct list_lru *lru, struct list_head *item);
/**
* list_lru_count_node: return the number of objects currently held by @lru
* @lru: the lru pointer.
* @nid: the node id to count from.
*
* Always return a non-negative number, 0 for empty lists. There is no
* guarantee that the list is not updated while the count is being computed.
* Callers that want such a guarantee need to provide an outer lock.
*/
unsigned long list_lru_count_node(struct list_lru *lru, int nid);
static inline unsigned long list_lru_count(struct list_lru *lru)
{
long count = 0;
int nid;
for_each_node_mask(nid, lru->active_nodes)
count += list_lru_count_node(lru, nid);
return count;
}
typedef enum lru_status
(*list_lru_walk_cb)(struct list_head *item, spinlock_t *lock, void *cb_arg);
/**
* list_lru_walk_node: walk a list_lru, isolating and disposing freeable items.
* @lru: the lru pointer.
* @nid: the node id to scan from.
* @isolate: callback function that is resposible for deciding what to do with
* the item currently being scanned
* @cb_arg: opaque type that will be passed to @isolate
* @nr_to_walk: how many items to scan.
*
* This function will scan all elements in a particular list_lru, calling the
* @isolate callback for each of those items, along with the current list
* spinlock and a caller-provided opaque. The @isolate callback can choose to
* drop the lock internally, but *must* return with the lock held. The callback
* will return an enum lru_status telling the list_lru infrastructure what to
* do with the object being scanned.
*
* Please note that nr_to_walk does not mean how many objects will be freed,
* just how many objects will be scanned.
*
* Return value: the number of objects effectively removed from the LRU.
*/
unsigned long list_lru_walk_node(struct list_lru *lru, int nid,
list_lru_walk_cb isolate, void *cb_arg,
unsigned long *nr_to_walk);
static inline unsigned long
list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate,
void *cb_arg, unsigned long nr_to_walk)
{
long isolated = 0;
int nid;
for_each_node_mask(nid, lru->active_nodes) {
isolated += list_lru_walk_node(lru, nid, isolate,
cb_arg, &nr_to_walk);
if (nr_to_walk <= 0)
break;
}
return isolated;
}
#endif /* _LRU_LIST_H */
|
