mirror of https://gitee.com/openkylin/linux.git
105 lines
2.3 KiB
C
105 lines
2.3 KiB
C
/* Copyright (c) 2016 Facebook
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#include "percpu_freelist.h"
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int pcpu_freelist_init(struct pcpu_freelist *s)
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{
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int cpu;
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s->freelist = alloc_percpu(struct pcpu_freelist_head);
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if (!s->freelist)
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return -ENOMEM;
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for_each_possible_cpu(cpu) {
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struct pcpu_freelist_head *head = per_cpu_ptr(s->freelist, cpu);
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raw_spin_lock_init(&head->lock);
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head->first = NULL;
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}
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return 0;
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}
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void pcpu_freelist_destroy(struct pcpu_freelist *s)
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{
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free_percpu(s->freelist);
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}
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static inline void __pcpu_freelist_push(struct pcpu_freelist_head *head,
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struct pcpu_freelist_node *node)
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{
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raw_spin_lock(&head->lock);
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node->next = head->first;
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head->first = node;
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raw_spin_unlock(&head->lock);
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}
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void pcpu_freelist_push(struct pcpu_freelist *s,
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struct pcpu_freelist_node *node)
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{
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struct pcpu_freelist_head *head = this_cpu_ptr(s->freelist);
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__pcpu_freelist_push(head, node);
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}
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void pcpu_freelist_populate(struct pcpu_freelist *s, void *buf, u32 elem_size,
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u32 nr_elems)
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{
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struct pcpu_freelist_head *head;
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unsigned long flags;
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int i, cpu, pcpu_entries;
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pcpu_entries = nr_elems / num_possible_cpus() + 1;
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i = 0;
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/* disable irq to workaround lockdep false positive
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* in bpf usage pcpu_freelist_populate() will never race
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* with pcpu_freelist_push()
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*/
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local_irq_save(flags);
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for_each_possible_cpu(cpu) {
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again:
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head = per_cpu_ptr(s->freelist, cpu);
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__pcpu_freelist_push(head, buf);
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i++;
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buf += elem_size;
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if (i == nr_elems)
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break;
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if (i % pcpu_entries)
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goto again;
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}
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local_irq_restore(flags);
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}
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struct pcpu_freelist_node *pcpu_freelist_pop(struct pcpu_freelist *s)
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{
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struct pcpu_freelist_head *head;
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struct pcpu_freelist_node *node;
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unsigned long flags;
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int orig_cpu, cpu;
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local_irq_save(flags);
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orig_cpu = cpu = raw_smp_processor_id();
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while (1) {
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head = per_cpu_ptr(s->freelist, cpu);
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raw_spin_lock(&head->lock);
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node = head->first;
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if (node) {
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head->first = node->next;
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raw_spin_unlock_irqrestore(&head->lock, flags);
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return node;
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}
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raw_spin_unlock(&head->lock);
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cpu = cpumask_next(cpu, cpu_possible_mask);
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if (cpu >= nr_cpu_ids)
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cpu = 0;
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if (cpu == orig_cpu) {
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local_irq_restore(flags);
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return NULL;
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}
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}
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}
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