// 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 = raw_smp_processor_id();	while (1) {		for_each_cpu_wrap(cpu, cpu_possible_mask, orig_cpu) {			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;			}		} 		/* cannot lock any per cpu lock, try extralist */		if (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;	unsigned int cpu, cpu_idx, i, j, n, m; 	n = nr_elems / num_possible_cpus();	m = nr_elems % num_possible_cpus(); 	cpu_idx = 0;	for_each_possible_cpu(cpu) {		head = per_cpu_ptr(s->freelist, cpu);		j = n + (cpu_idx < m ? 1 : 0);		for (i = 0; i < j; i++) {			/* No locking required as this is not visible yet. */			pcpu_freelist_push_node(head, buf);			buf += elem_size;		}		cpu_idx++;	}} static struct pcpu_freelist_node *___pcpu_freelist_pop(struct pcpu_freelist *s){	struct pcpu_freelist_head *head;	struct pcpu_freelist_node *node;	int cpu; 	for_each_cpu_wrap(cpu, cpu_possible_mask, raw_smp_processor_id()) {		head = per_cpu_ptr(s->freelist, cpu);		if (!READ_ONCE(head->first))			continue;		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);	} 	/* 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 cpu; 	for_each_cpu_wrap(cpu, cpu_possible_mask, raw_smp_processor_id()) {		head = per_cpu_ptr(s->freelist, cpu);		if (!READ_ONCE(head->first))			continue;		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);		}	} 	/* 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;}