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1// SPDX-License-Identifier: GPL-2.0-only
2/* Copyright (c) 2016 Facebook
3 */
4#include "percpu_freelist.h"
5
6int pcpu_freelist_init(struct pcpu_freelist *s)
7{
8 int cpu;
9
10 s->freelist = alloc_percpu(struct pcpu_freelist_head);
11 if (!s->freelist)
12 return -ENOMEM;
13
14 for_each_possible_cpu(cpu) {
15 struct pcpu_freelist_head *head = per_cpu_ptr(s->freelist, cpu);
16
17 raw_spin_lock_init(&head->lock);
18 head->first = NULL;
19 }
20 raw_spin_lock_init(&s->extralist.lock);
21 s->extralist.first = NULL;
22 return 0;
23}
24
25void pcpu_freelist_destroy(struct pcpu_freelist *s)
26{
27 free_percpu(s->freelist);
28}
29
30static inline void pcpu_freelist_push_node(struct pcpu_freelist_head *head,
31 struct pcpu_freelist_node *node)
32{
33 node->next = head->first;
34 WRITE_ONCE(head->first, node);
35}
36
37static inline void ___pcpu_freelist_push(struct pcpu_freelist_head *head,
38 struct pcpu_freelist_node *node)
39{
40 raw_spin_lock(&head->lock);
41 pcpu_freelist_push_node(head, node);
42 raw_spin_unlock(&head->lock);
43}
44
45static inline bool pcpu_freelist_try_push_extra(struct pcpu_freelist *s,
46 struct pcpu_freelist_node *node)
47{
48 if (!raw_spin_trylock(&s->extralist.lock))
49 return false;
50
51 pcpu_freelist_push_node(&s->extralist, node);
52 raw_spin_unlock(&s->extralist.lock);
53 return true;
54}
55
56static inline void ___pcpu_freelist_push_nmi(struct pcpu_freelist *s,
57 struct pcpu_freelist_node *node)
58{
59 int cpu, orig_cpu;
60
61 orig_cpu = raw_smp_processor_id();
62 while (1) {
63 for_each_cpu_wrap(cpu, cpu_possible_mask, orig_cpu) {
64 struct pcpu_freelist_head *head;
65
66 head = per_cpu_ptr(s->freelist, cpu);
67 if (raw_spin_trylock(&head->lock)) {
68 pcpu_freelist_push_node(head, node);
69 raw_spin_unlock(&head->lock);
70 return;
71 }
72 }
73
74 /* cannot lock any per cpu lock, try extralist */
75 if (pcpu_freelist_try_push_extra(s, node))
76 return;
77 }
78}
79
80void __pcpu_freelist_push(struct pcpu_freelist *s,
81 struct pcpu_freelist_node *node)
82{
83 if (in_nmi())
84 ___pcpu_freelist_push_nmi(s, node);
85 else
86 ___pcpu_freelist_push(this_cpu_ptr(s->freelist), node);
87}
88
89void pcpu_freelist_push(struct pcpu_freelist *s,
90 struct pcpu_freelist_node *node)
91{
92 unsigned long flags;
93
94 local_irq_save(flags);
95 __pcpu_freelist_push(s, node);
96 local_irq_restore(flags);
97}
98
99void pcpu_freelist_populate(struct pcpu_freelist *s, void *buf, u32 elem_size,
100 u32 nr_elems)
101{
102 struct pcpu_freelist_head *head;
103 unsigned int cpu, cpu_idx, i, j, n, m;
104
105 n = nr_elems / num_possible_cpus();
106 m = nr_elems % num_possible_cpus();
107
108 cpu_idx = 0;
109 for_each_possible_cpu(cpu) {
110 head = per_cpu_ptr(s->freelist, cpu);
111 j = n + (cpu_idx < m ? 1 : 0);
112 for (i = 0; i < j; i++) {
113 /* No locking required as this is not visible yet. */
114 pcpu_freelist_push_node(head, buf);
115 buf += elem_size;
116 }
117 cpu_idx++;
118 }
119}
120
121static struct pcpu_freelist_node *___pcpu_freelist_pop(struct pcpu_freelist *s)
122{
123 struct pcpu_freelist_head *head;
124 struct pcpu_freelist_node *node;
125 int cpu;
126
127 for_each_cpu_wrap(cpu, cpu_possible_mask, raw_smp_processor_id()) {
128 head = per_cpu_ptr(s->freelist, cpu);
129 if (!READ_ONCE(head->first))
130 continue;
131 raw_spin_lock(&head->lock);
132 node = head->first;
133 if (node) {
134 WRITE_ONCE(head->first, node->next);
135 raw_spin_unlock(&head->lock);
136 return node;
137 }
138 raw_spin_unlock(&head->lock);
139 }
140
141 /* per cpu lists are all empty, try extralist */
142 if (!READ_ONCE(s->extralist.first))
143 return NULL;
144 raw_spin_lock(&s->extralist.lock);
145 node = s->extralist.first;
146 if (node)
147 WRITE_ONCE(s->extralist.first, node->next);
148 raw_spin_unlock(&s->extralist.lock);
149 return node;
150}
151
152static struct pcpu_freelist_node *
153___pcpu_freelist_pop_nmi(struct pcpu_freelist *s)
154{
155 struct pcpu_freelist_head *head;
156 struct pcpu_freelist_node *node;
157 int cpu;
158
159 for_each_cpu_wrap(cpu, cpu_possible_mask, raw_smp_processor_id()) {
160 head = per_cpu_ptr(s->freelist, cpu);
161 if (!READ_ONCE(head->first))
162 continue;
163 if (raw_spin_trylock(&head->lock)) {
164 node = head->first;
165 if (node) {
166 WRITE_ONCE(head->first, node->next);
167 raw_spin_unlock(&head->lock);
168 return node;
169 }
170 raw_spin_unlock(&head->lock);
171 }
172 }
173
174 /* cannot pop from per cpu lists, try extralist */
175 if (!READ_ONCE(s->extralist.first) || !raw_spin_trylock(&s->extralist.lock))
176 return NULL;
177 node = s->extralist.first;
178 if (node)
179 WRITE_ONCE(s->extralist.first, node->next);
180 raw_spin_unlock(&s->extralist.lock);
181 return node;
182}
183
184struct pcpu_freelist_node *__pcpu_freelist_pop(struct pcpu_freelist *s)
185{
186 if (in_nmi())
187 return ___pcpu_freelist_pop_nmi(s);
188 return ___pcpu_freelist_pop(s);
189}
190
191struct pcpu_freelist_node *pcpu_freelist_pop(struct pcpu_freelist *s)
192{
193 struct pcpu_freelist_node *ret;
194 unsigned long flags;
195
196 local_irq_save(flags);
197 ret = __pcpu_freelist_pop(s);
198 local_irq_restore(flags);
199 return ret;
200}
1// SPDX-License-Identifier: GPL-2.0-only
2/* Copyright (c) 2016 Facebook
3 */
4#include "percpu_freelist.h"
5
6int pcpu_freelist_init(struct pcpu_freelist *s)
7{
8 int cpu;
9
10 s->freelist = alloc_percpu(struct pcpu_freelist_head);
11 if (!s->freelist)
12 return -ENOMEM;
13
14 for_each_possible_cpu(cpu) {
15 struct pcpu_freelist_head *head = per_cpu_ptr(s->freelist, cpu);
16
17 raw_spin_lock_init(&head->lock);
18 head->first = NULL;
19 }
20 raw_spin_lock_init(&s->extralist.lock);
21 s->extralist.first = NULL;
22 return 0;
23}
24
25void pcpu_freelist_destroy(struct pcpu_freelist *s)
26{
27 free_percpu(s->freelist);
28}
29
30static inline void pcpu_freelist_push_node(struct pcpu_freelist_head *head,
31 struct pcpu_freelist_node *node)
32{
33 node->next = head->first;
34 head->first = node;
35}
36
37static inline void ___pcpu_freelist_push(struct pcpu_freelist_head *head,
38 struct pcpu_freelist_node *node)
39{
40 raw_spin_lock(&head->lock);
41 pcpu_freelist_push_node(head, node);
42 raw_spin_unlock(&head->lock);
43}
44
45static inline bool pcpu_freelist_try_push_extra(struct pcpu_freelist *s,
46 struct pcpu_freelist_node *node)
47{
48 if (!raw_spin_trylock(&s->extralist.lock))
49 return false;
50
51 pcpu_freelist_push_node(&s->extralist, node);
52 raw_spin_unlock(&s->extralist.lock);
53 return true;
54}
55
56static inline void ___pcpu_freelist_push_nmi(struct pcpu_freelist *s,
57 struct pcpu_freelist_node *node)
58{
59 int cpu, orig_cpu;
60
61 orig_cpu = cpu = raw_smp_processor_id();
62 while (1) {
63 struct pcpu_freelist_head *head;
64
65 head = per_cpu_ptr(s->freelist, cpu);
66 if (raw_spin_trylock(&head->lock)) {
67 pcpu_freelist_push_node(head, node);
68 raw_spin_unlock(&head->lock);
69 return;
70 }
71 cpu = cpumask_next(cpu, cpu_possible_mask);
72 if (cpu >= nr_cpu_ids)
73 cpu = 0;
74
75 /* cannot lock any per cpu lock, try extralist */
76 if (cpu == orig_cpu &&
77 pcpu_freelist_try_push_extra(s, node))
78 return;
79 }
80}
81
82void __pcpu_freelist_push(struct pcpu_freelist *s,
83 struct pcpu_freelist_node *node)
84{
85 if (in_nmi())
86 ___pcpu_freelist_push_nmi(s, node);
87 else
88 ___pcpu_freelist_push(this_cpu_ptr(s->freelist), node);
89}
90
91void pcpu_freelist_push(struct pcpu_freelist *s,
92 struct pcpu_freelist_node *node)
93{
94 unsigned long flags;
95
96 local_irq_save(flags);
97 __pcpu_freelist_push(s, node);
98 local_irq_restore(flags);
99}
100
101void pcpu_freelist_populate(struct pcpu_freelist *s, void *buf, u32 elem_size,
102 u32 nr_elems)
103{
104 struct pcpu_freelist_head *head;
105 int i, cpu, pcpu_entries;
106
107 pcpu_entries = nr_elems / num_possible_cpus() + 1;
108 i = 0;
109
110 for_each_possible_cpu(cpu) {
111again:
112 head = per_cpu_ptr(s->freelist, cpu);
113 /* No locking required as this is not visible yet. */
114 pcpu_freelist_push_node(head, buf);
115 i++;
116 buf += elem_size;
117 if (i == nr_elems)
118 break;
119 if (i % pcpu_entries)
120 goto again;
121 }
122}
123
124static struct pcpu_freelist_node *___pcpu_freelist_pop(struct pcpu_freelist *s)
125{
126 struct pcpu_freelist_head *head;
127 struct pcpu_freelist_node *node;
128 int orig_cpu, cpu;
129
130 orig_cpu = cpu = raw_smp_processor_id();
131 while (1) {
132 head = per_cpu_ptr(s->freelist, cpu);
133 raw_spin_lock(&head->lock);
134 node = head->first;
135 if (node) {
136 head->first = node->next;
137 raw_spin_unlock(&head->lock);
138 return node;
139 }
140 raw_spin_unlock(&head->lock);
141 cpu = cpumask_next(cpu, cpu_possible_mask);
142 if (cpu >= nr_cpu_ids)
143 cpu = 0;
144 if (cpu == orig_cpu)
145 break;
146 }
147
148 /* per cpu lists are all empty, try extralist */
149 raw_spin_lock(&s->extralist.lock);
150 node = s->extralist.first;
151 if (node)
152 s->extralist.first = node->next;
153 raw_spin_unlock(&s->extralist.lock);
154 return node;
155}
156
157static struct pcpu_freelist_node *
158___pcpu_freelist_pop_nmi(struct pcpu_freelist *s)
159{
160 struct pcpu_freelist_head *head;
161 struct pcpu_freelist_node *node;
162 int orig_cpu, cpu;
163
164 orig_cpu = cpu = raw_smp_processor_id();
165 while (1) {
166 head = per_cpu_ptr(s->freelist, cpu);
167 if (raw_spin_trylock(&head->lock)) {
168 node = head->first;
169 if (node) {
170 head->first = node->next;
171 raw_spin_unlock(&head->lock);
172 return node;
173 }
174 raw_spin_unlock(&head->lock);
175 }
176 cpu = cpumask_next(cpu, cpu_possible_mask);
177 if (cpu >= nr_cpu_ids)
178 cpu = 0;
179 if (cpu == orig_cpu)
180 break;
181 }
182
183 /* cannot pop from per cpu lists, try extralist */
184 if (!raw_spin_trylock(&s->extralist.lock))
185 return NULL;
186 node = s->extralist.first;
187 if (node)
188 s->extralist.first = node->next;
189 raw_spin_unlock(&s->extralist.lock);
190 return node;
191}
192
193struct pcpu_freelist_node *__pcpu_freelist_pop(struct pcpu_freelist *s)
194{
195 if (in_nmi())
196 return ___pcpu_freelist_pop_nmi(s);
197 return ___pcpu_freelist_pop(s);
198}
199
200struct pcpu_freelist_node *pcpu_freelist_pop(struct pcpu_freelist *s)
201{
202 struct pcpu_freelist_node *ret;
203 unsigned long flags;
204
205 local_irq_save(flags);
206 ret = __pcpu_freelist_pop(s);
207 local_irq_restore(flags);
208 return ret;
209}