1 files changed, 200 insertions, 0 deletions
diff --git a/kernel/bpf/percpu_freelist.c b/kernel/bpf/percpu_freelist.c
new file mode 100644
index 000000000..034cf87b5
--- /dev/null
+++ b/kernel/bpf/percpu_freelist.c
@@ -0,0 +1,200 @@
+// 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;
+}