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// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2016 Facebook
*/
#include "percpu_freelist.h"
int pcpu_freelist_init(struct pcpu_freelist *s)
{
int cpu;
s->freelist = alloc_percpu(struct pcpu_freelist_head);
if (!s->freelist)
return -ENOMEM;
for_each_possible_cpu(cpu) {
struct pcpu_freelist_head *head = per_cpu_ptr(s->freelist, cpu);
raw_spin_lock_init(&head->lock);
head->first = NULL;
}
raw_spin_lock_init(&s->extralist.lock);
s->extralist.first = NULL;
return 0;
}
void pcpu_freelist_destroy(struct pcpu_freelist *s)
{
free_percpu(s->freelist);
}
static inline void pcpu_freelist_push_node(struct pcpu_freelist_head *head,
struct pcpu_freelist_node *node)
{
node->next = head->first;
WRITE_ONCE(head->first, node);
}
static inline void ___pcpu_freelist_push(struct pcpu_freelist_head *head,
struct pcpu_freelist_node *node)
{
raw_spin_lock(&head->lock);
pcpu_freelist_push_node(head, node);
raw_spin_unlock(&head->lock);
}
static inline bool pcpu_freelist_try_push_extra(struct pcpu_freelist *s,
struct pcpu_freelist_node *node)
{
if (!raw_spin_trylock(&s->extralist.lock))
return false;
pcpu_freelist_push_node(&s->extralist, node);
raw_spin_unlock(&s->extralist.lock);
return true;
}
static inline void ___pcpu_freelist_push_nmi(struct pcpu_freelist *s,
struct pcpu_freelist_node *node)
{
int cpu, orig_cpu;
orig_cpu = cpu = raw_smp_processor_id();
while (1) {
struct pcpu_freelist_head *head;
head = per_cpu_ptr(s->freelist, cpu);
if (raw_spin_trylock(&head->lock)) {
pcpu_freelist_push_node(head, node);
raw_spin_unlock(&head->lock);
return;
}
cpu = cpumask_next(cpu, cpu_possible_mask);
if (cpu >= nr_cpu_ids)
cpu = 0;
/* cannot lock any per cpu lock, try extralist */
if (cpu == orig_cpu &&
pcpu_freelist_try_push_extra(s, node))
return;
}
}
void __pcpu_freelist_push(struct pcpu_freelist *s,
struct pcpu_freelist_node *node)
{
if (in_nmi())
___pcpu_freelist_push_nmi(s, node);
else
___pcpu_freelist_push(this_cpu_ptr(s->freelist), node);
}
void pcpu_freelist_push(struct pcpu_freelist *s,
struct pcpu_freelist_node *node)
{
unsigned long flags;
local_irq_save(flags);
__pcpu_freelist_push(s, node);
local_irq_restore(flags);
}
void pcpu_freelist_populate(struct pcpu_freelist *s, void *buf, u32 elem_size,
u32 nr_elems)
{
struct pcpu_freelist_head *head;
int i, cpu, pcpu_entries;
pcpu_entries = nr_elems / num_possible_cpus() + 1;
i = 0;
for_each_possible_cpu(cpu) {
again:
head = per_cpu_ptr(s->freelist, cpu);
/* No locking required as this is not visible yet. */
pcpu_freelist_push_node(head, buf);
i++;
buf += elem_size;
if (i == nr_elems)
break;
if (i % pcpu_entries)
goto again;
}
}
static struct pcpu_freelist_node *___pcpu_freelist_pop(struct pcpu_freelist *s)
{
struct pcpu_freelist_head *head;
struct pcpu_freelist_node *node;
int orig_cpu, cpu;
orig_cpu = cpu = raw_smp_processor_id();
while (1) {
head = per_cpu_ptr(s->freelist, cpu);
if (!READ_ONCE(head->first))
goto next_cpu;
raw_spin_lock(&head->lock);
node = head->first;
if (node) {
WRITE_ONCE(head->first, node->next);
raw_spin_unlock(&head->lock);
return node;
}
raw_spin_unlock(&head->lock);
next_cpu:
cpu = cpumask_next(cpu, cpu_possible_mask);
if (cpu >= nr_cpu_ids)
cpu = 0;
if (cpu == orig_cpu)
break;
}
/* per cpu lists are all empty, try extralist */
if (!READ_ONCE(s->extralist.first))
return NULL;
raw_spin_lock(&s->extralist.lock);
node = s->extralist.first;
if (node)
WRITE_ONCE(s->extralist.first, node->next);
raw_spin_unlock(&s->extralist.lock);
return node;
}
static struct pcpu_freelist_node *
___pcpu_freelist_pop_nmi(struct pcpu_freelist *s)
{
struct pcpu_freelist_head *head;
struct pcpu_freelist_node *node;
int orig_cpu, cpu;
orig_cpu = cpu = raw_smp_processor_id();
while (1) {
head = per_cpu_ptr(s->freelist, cpu);
if (!READ_ONCE(head->first))
goto next_cpu;
if (raw_spin_trylock(&head->lock)) {
node = head->first;
if (node) {
WRITE_ONCE(head->first, node->next);
raw_spin_unlock(&head->lock);
return node;
}
raw_spin_unlock(&head->lock);
}
next_cpu:
cpu = cpumask_next(cpu, cpu_possible_mask);
if (cpu >= nr_cpu_ids)
cpu = 0;
if (cpu == orig_cpu)
break;
}
/* cannot pop from per cpu lists, try extralist */
if (!READ_ONCE(s->extralist.first) || !raw_spin_trylock(&s->extralist.lock))
return NULL;
node = s->extralist.first;
if (node)
WRITE_ONCE(s->extralist.first, node->next);
raw_spin_unlock(&s->extralist.lock);
return node;
}
struct pcpu_freelist_node *__pcpu_freelist_pop(struct pcpu_freelist *s)
{
if (in_nmi())
return ___pcpu_freelist_pop_nmi(s);
return ___pcpu_freelist_pop(s);
}
struct pcpu_freelist_node *pcpu_freelist_pop(struct pcpu_freelist *s)
{
struct pcpu_freelist_node *ret;
unsigned long flags;
local_irq_save(flags);
ret = __pcpu_freelist_pop(s);
local_irq_restore(flags);
return ret;
}
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