treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 206
[muen/linux.git] / kernel / bpf / percpu_freelist.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2016 Facebook
3  */
4 #include "percpu_freelist.h"
5
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         return 0;
21 }
22
23 void pcpu_freelist_destroy(struct pcpu_freelist *s)
24 {
25         free_percpu(s->freelist);
26 }
27
28 static inline void ___pcpu_freelist_push(struct pcpu_freelist_head *head,
29                                          struct pcpu_freelist_node *node)
30 {
31         raw_spin_lock(&head->lock);
32         node->next = head->first;
33         head->first = node;
34         raw_spin_unlock(&head->lock);
35 }
36
37 void __pcpu_freelist_push(struct pcpu_freelist *s,
38                         struct pcpu_freelist_node *node)
39 {
40         struct pcpu_freelist_head *head = this_cpu_ptr(s->freelist);
41
42         ___pcpu_freelist_push(head, node);
43 }
44
45 void pcpu_freelist_push(struct pcpu_freelist *s,
46                         struct pcpu_freelist_node *node)
47 {
48         unsigned long flags;
49
50         local_irq_save(flags);
51         __pcpu_freelist_push(s, node);
52         local_irq_restore(flags);
53 }
54
55 void pcpu_freelist_populate(struct pcpu_freelist *s, void *buf, u32 elem_size,
56                             u32 nr_elems)
57 {
58         struct pcpu_freelist_head *head;
59         unsigned long flags;
60         int i, cpu, pcpu_entries;
61
62         pcpu_entries = nr_elems / num_possible_cpus() + 1;
63         i = 0;
64
65         /* disable irq to workaround lockdep false positive
66          * in bpf usage pcpu_freelist_populate() will never race
67          * with pcpu_freelist_push()
68          */
69         local_irq_save(flags);
70         for_each_possible_cpu(cpu) {
71 again:
72                 head = per_cpu_ptr(s->freelist, cpu);
73                 ___pcpu_freelist_push(head, buf);
74                 i++;
75                 buf += elem_size;
76                 if (i == nr_elems)
77                         break;
78                 if (i % pcpu_entries)
79                         goto again;
80         }
81         local_irq_restore(flags);
82 }
83
84 struct pcpu_freelist_node *__pcpu_freelist_pop(struct pcpu_freelist *s)
85 {
86         struct pcpu_freelist_head *head;
87         struct pcpu_freelist_node *node;
88         int orig_cpu, cpu;
89
90         orig_cpu = cpu = raw_smp_processor_id();
91         while (1) {
92                 head = per_cpu_ptr(s->freelist, cpu);
93                 raw_spin_lock(&head->lock);
94                 node = head->first;
95                 if (node) {
96                         head->first = node->next;
97                         raw_spin_unlock(&head->lock);
98                         return node;
99                 }
100                 raw_spin_unlock(&head->lock);
101                 cpu = cpumask_next(cpu, cpu_possible_mask);
102                 if (cpu >= nr_cpu_ids)
103                         cpu = 0;
104                 if (cpu == orig_cpu)
105                         return NULL;
106         }
107 }
108
109 struct pcpu_freelist_node *pcpu_freelist_pop(struct pcpu_freelist *s)
110 {
111         struct pcpu_freelist_node *ret;
112         unsigned long flags;
113
114         local_irq_save(flags);
115         ret = __pcpu_freelist_pop(s);
116         local_irq_restore(flags);
117         return ret;
118 }