// SPDX-License-Identifier: GPL-2.0-only
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/* Copyright (c) 2016 Facebook
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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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raw_spin_lock_init(&s->extralist.lock);
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s->extralist.first = NULL;
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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_node(struct pcpu_freelist_head *head,
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struct pcpu_freelist_node *node)
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{
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node->next = head->first;
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head->first = node;
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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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pcpu_freelist_push_node(head, node);
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raw_spin_unlock(&head->lock);
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}
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static inline bool pcpu_freelist_try_push_extra(struct pcpu_freelist *s,
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struct pcpu_freelist_node *node)
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{
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if (!raw_spin_trylock(&s->extralist.lock))
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return false;
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pcpu_freelist_push_node(&s->extralist, node);
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raw_spin_unlock(&s->extralist.lock);
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return true;
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}
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static inline void ___pcpu_freelist_push_nmi(struct pcpu_freelist *s,
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struct pcpu_freelist_node *node)
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{
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int cpu, orig_cpu;
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orig_cpu = cpu = raw_smp_processor_id();
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while (1) {
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struct pcpu_freelist_head *head;
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head = per_cpu_ptr(s->freelist, cpu);
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if (raw_spin_trylock(&head->lock)) {
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pcpu_freelist_push_node(head, node);
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raw_spin_unlock(&head->lock);
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return;
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}
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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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/* cannot lock any per cpu lock, try extralist */
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if (cpu == orig_cpu &&
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pcpu_freelist_try_push_extra(s, node))
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return;
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}
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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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if (in_nmi())
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___pcpu_freelist_push_nmi(s, node);
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else
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___pcpu_freelist_push(this_cpu_ptr(s->freelist), node);
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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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unsigned long flags;
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local_irq_save(flags);
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__pcpu_freelist_push(s, node);
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local_irq_restore(flags);
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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 int cpu, cpu_idx, i, j, n, m;
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n = nr_elems / num_possible_cpus();
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m = nr_elems % num_possible_cpus();
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cpu_idx = 0;
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for_each_possible_cpu(cpu) {
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head = per_cpu_ptr(s->freelist, cpu);
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j = n + (cpu_idx < m ? 1 : 0);
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for (i = 0; i < j; i++) {
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/* No locking required as this is not visible yet. */
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pcpu_freelist_push_node(head, buf);
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buf += elem_size;
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}
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cpu_idx++;
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}
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}
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static 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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int orig_cpu, cpu;
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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(&head->lock);
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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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break;
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}
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/* per cpu lists are all empty, try extralist */
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raw_spin_lock(&s->extralist.lock);
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node = s->extralist.first;
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if (node)
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s->extralist.first = node->next;
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raw_spin_unlock(&s->extralist.lock);
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return node;
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}
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static struct pcpu_freelist_node *
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___pcpu_freelist_pop_nmi(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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int orig_cpu, cpu;
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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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if (raw_spin_trylock(&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(&head->lock);
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return node;
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}
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raw_spin_unlock(&head->lock);
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}
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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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break;
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}
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/* cannot pop from per cpu lists, try extralist */
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if (!raw_spin_trylock(&s->extralist.lock))
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return NULL;
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node = s->extralist.first;
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if (node)
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s->extralist.first = node->next;
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raw_spin_unlock(&s->extralist.lock);
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return node;
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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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if (in_nmi())
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return ___pcpu_freelist_pop_nmi(s);
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return ___pcpu_freelist_pop(s);
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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_node *ret;
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unsigned long flags;
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local_irq_save(flags);
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ret = __pcpu_freelist_pop(s);
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local_irq_restore(flags);
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return ret;
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}
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