1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2016 Facebook
3 */
4 #include "percpu_freelist.h"
5
pcpu_freelist_init(struct pcpu_freelist * s)6 int 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
pcpu_freelist_destroy(struct pcpu_freelist * s)25 void pcpu_freelist_destroy(struct pcpu_freelist *s)
26 {
27 free_percpu(s->freelist);
28 }
29
pcpu_freelist_push_node(struct pcpu_freelist_head * head,struct pcpu_freelist_node * node)30 static 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
___pcpu_freelist_push(struct pcpu_freelist_head * head,struct pcpu_freelist_node * node)37 static 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
pcpu_freelist_try_push_extra(struct pcpu_freelist * s,struct pcpu_freelist_node * node)45 static 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
___pcpu_freelist_push_nmi(struct pcpu_freelist * s,struct pcpu_freelist_node * node)56 static 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
__pcpu_freelist_push(struct pcpu_freelist * s,struct pcpu_freelist_node * node)82 void __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
pcpu_freelist_push(struct pcpu_freelist * s,struct pcpu_freelist_node * node)91 void 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
pcpu_freelist_populate(struct pcpu_freelist * s,void * buf,u32 elem_size,u32 nr_elems)101 void 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) {
111 again:
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
___pcpu_freelist_pop(struct pcpu_freelist * s)124 static 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
157 static struct pcpu_freelist_node *
___pcpu_freelist_pop_nmi(struct pcpu_freelist * s)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
__pcpu_freelist_pop(struct pcpu_freelist * s)193 struct 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
pcpu_freelist_pop(struct pcpu_freelist * s)200 struct 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 }
210
