1 /*
2 * linux/mm/allocpercpu.c
3 *
4 * Separated from slab.c August 11, 2006 Christoph Lameter
5 */
6 #include <linux/mm.h>
7 #include <linux/module.h>
8
9 #ifndef cache_line_size
10 #define cache_line_size() L1_CACHE_BYTES
11 #endif
12
13 /**
14 * percpu_depopulate - depopulate per-cpu data for given cpu
15 * @__pdata: per-cpu data to depopulate
16 * @cpu: depopulate per-cpu data for this cpu
17 *
18 * Depopulating per-cpu data for a cpu going offline would be a typical
19 * use case. You need to register a cpu hotplug handler for that purpose.
20 */
21 static void percpu_depopulate(void *__pdata, int cpu)
22 {
23 struct percpu_data *pdata = __percpu_disguise(__pdata);
24
25 kfree(pdata->ptrs[cpu]);
26 pdata->ptrs[cpu] = NULL;
27 }
28
29 /**
30 * percpu_depopulate_mask - depopulate per-cpu data for some cpu's
31 * @__pdata: per-cpu data to depopulate
32 * @mask: depopulate per-cpu data for cpu's selected through mask bits
33 */
34 static void __percpu_depopulate_mask(void *__pdata, const cpumask_t *mask)
35 {
36 int cpu;
37 for_each_cpu_mask_nr(cpu, *mask)
38 percpu_depopulate(__pdata, cpu);
39 }
40
41 #define percpu_depopulate_mask(__pdata, mask) \
42 __percpu_depopulate_mask((__pdata), &(mask))
43
44 /**
45 * percpu_populate - populate per-cpu data for given cpu
46 * @__pdata: per-cpu data to populate further
47 * @size: size of per-cpu object
48 * @gfp: may sleep or not etc.
49 * @cpu: populate per-data for this cpu
50 *
51 * Populating per-cpu data for a cpu coming online would be a typical
52 * use case. You need to register a cpu hotplug handler for that purpose.
53 * Per-cpu object is populated with zeroed buffer.
54 */
55 static void *percpu_populate(void *__pdata, size_t size, gfp_t gfp, int cpu)
56 {
57 struct percpu_data *pdata = __percpu_disguise(__pdata);
58 int node = cpu_to_node(cpu);
59
60 /*
61 * We should make sure each CPU gets private memory.
62 */
63 size = roundup(size, cache_line_size());
64
65 BUG_ON(pdata->ptrs[cpu]);
66 if (node_online(node))
67 pdata->ptrs[cpu] = kmalloc_node(size, gfp|__GFP_ZERO, node);
68 else
69 pdata->ptrs[cpu] = kzalloc(size, gfp);
70 return pdata->ptrs[cpu];
71 }
72
73 /**
74 * percpu_populate_mask - populate per-cpu data for more cpu's
75 * @__pdata: per-cpu data to populate further
76 * @size: size of per-cpu object
77 * @gfp: may sleep or not etc.
78 * @mask: populate per-cpu data for cpu's selected through mask bits
79 *
80 * Per-cpu objects are populated with zeroed buffers.
81 */
82 static int __percpu_populate_mask(void *__pdata, size_t size, gfp_t gfp,
83 cpumask_t *mask)
84 {
85 cpumask_t populated;
86 int cpu;
87
88 cpus_clear(populated);
89 for_each_cpu_mask_nr(cpu, *mask)
90 if (unlikely(!percpu_populate(__pdata, size, gfp, cpu))) {
91 __percpu_depopulate_mask(__pdata, &populated);
92 return -ENOMEM;
93 } else
94 cpu_set(cpu, populated);
95 return 0;
96 }
97
98 #define percpu_populate_mask(__pdata, size, gfp, mask) \
99 __percpu_populate_mask((__pdata), (size), (gfp), &(mask))
100
101 /**
102 * alloc_percpu - initial setup of per-cpu data
103 * @size: size of per-cpu object
104 * @align: alignment
105 *
106 * Allocate dynamic percpu area. Percpu objects are populated with
107 * zeroed buffers.
108 */
109 void *__alloc_percpu(size_t size, size_t align)
110 {
111 /*
112 * We allocate whole cache lines to avoid false sharing
113 */
114 size_t sz = roundup(nr_cpu_ids * sizeof(void *), cache_line_size());
115 void *pdata = kzalloc(sz, GFP_KERNEL);
116 void *__pdata = __percpu_disguise(pdata);
117
118 /*
119 * Can't easily make larger alignment work with kmalloc. WARN
120 * on it. Larger alignment should only be used for module
121 * percpu sections on SMP for which this path isn't used.
122 */
123 WARN_ON_ONCE(align > SMP_CACHE_BYTES);
124
125 if (unlikely(!pdata))
126 return NULL;
127 if (likely(!__percpu_populate_mask(__pdata, size, GFP_KERNEL,
128 &cpu_possible_map)))
129 return __pdata;
130 kfree(pdata);
131 return NULL;
132 }
133 EXPORT_SYMBOL_GPL(__alloc_percpu);
134
135 /**
136 * free_percpu - final cleanup of per-cpu data
137 * @__pdata: object to clean up
138 *
139 * We simply clean up any per-cpu object left. No need for the client to
140 * track and specify through a bis mask which per-cpu objects are to free.
141 */
142 void free_percpu(void *__pdata)
143 {
144 if (unlikely(!__pdata))
145 return;
146 __percpu_depopulate_mask(__pdata, cpu_possible_mask);
147 kfree(__percpu_disguise(__pdata));
148 }
149 EXPORT_SYMBOL_GPL(free_percpu);
150
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