1 files changed, 26 insertions, 34 deletions

diff --git a/kernel/bpf/percpu_freelist.c b/kernel/bpf/percpu_freelist.c
index 3d897de89061..b6e7f5c5b9ab 100644
--- a/kernel/bpf/percpu_freelist.c
+++ b/kernel/bpf/percpu_freelist.c
@@ -31,7 +31,7 @@ static inline void pcpu_freelist_push_node(struct pcpu_freelist_head *head,
 					   struct pcpu_freelist_node *node)
 {
 	node->next = head->first;
-	head->first = node;
+	WRITE_ONCE(head->first, node);
 }
 
 static inline void ___pcpu_freelist_push(struct pcpu_freelist_head *head,
@@ -58,23 +58,21 @@ static inline void ___pcpu_freelist_push_nmi(struct pcpu_freelist *s,
 {
 	int cpu, orig_cpu;
 
-	orig_cpu = cpu = raw_smp_processor_id();
+	orig_cpu = raw_smp_processor_id();
 	while (1) {
-		struct pcpu_freelist_head *head;
+		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;
+			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))
+		if (pcpu_freelist_try_push_extra(s, node))
 			return;
 	}
 }
@@ -125,31 +123,29 @@ 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;
+	int cpu;
 
-	orig_cpu = cpu = raw_smp_processor_id();
-	while (1) {
+	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) {
-			head->first = node->next;
+			WRITE_ONCE(head->first, node->next);
 			raw_spin_unlock(&head->lock);
 			return node;
 		}
 		raw_spin_unlock(&head->lock);
-		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)
-		s->extralist.first = node->next;
+		WRITE_ONCE(s->extralist.first, node->next);
 	raw_spin_unlock(&s->extralist.lock);
 	return node;
 }
@@ -159,33 +155,29 @@ ___pcpu_freelist_pop_nmi(struct pcpu_freelist *s)
 {
 	struct pcpu_freelist_head *head;
 	struct pcpu_freelist_node *node;
-	int orig_cpu, cpu;
+	int cpu;
 
-	orig_cpu = cpu = raw_smp_processor_id();
-	while (1) {
+	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) {
-				head->first = node->next;
+				WRITE_ONCE(head->first, node->next);
 				raw_spin_unlock(&head->lock);
 				return node;
 			}
 			raw_spin_unlock(&head->lock);
 		}
-		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 (!raw_spin_trylock(&s->extralist.lock))
+	if (!READ_ONCE(s->extralist.first) || !raw_spin_trylock(&s->extralist.lock))
 		return NULL;
 	node = s->extralist.first;
 	if (node)
-		s->extralist.first = node->next;
+		WRITE_ONCE(s->extralist.first, node->next);
 	raw_spin_unlock(&s->extralist.lock);
 	return node;
 }