[RFC PATCH bpf-next 2/6] bpf: Factor out a common helper free_llist()

[Hou Tao <houtao@xxxxxxxxxxxxxxx>]

From: Hou Tao <houtao1@xxxxxxxxxx>

Factor out a common helper free_llist() to free normal elements or
per-cpu elements on a lock-less list.

Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
 kernel/bpf/memalloc.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c
index ac5b92fece14..3ad2e25946b5 100644
--- a/kernel/bpf/memalloc.c
+++ b/kernel/bpf/memalloc.c
@@ -217,9 +217,9 @@ static void alloc_bulk(struct bpf_mem_cache *c, int cnt, int node)
 	mem_cgroup_put(memcg);
 }
 
-static void free_one(struct bpf_mem_cache *c, void *obj)
+static void free_one(void *obj, bool percpu)
 {
-	if (c->percpu_size) {
+	if (percpu) {
 		free_percpu(((void **)obj)[1]);
 		kfree(obj);
 		return;
@@ -228,14 +228,19 @@ static void free_one(struct bpf_mem_cache *c, void *obj)
 	kfree(obj);
 }
 
-static void __free_rcu(struct rcu_head *head)
+static void free_llist(struct llist_node *llnode, bool percpu)
 {
-	struct bpf_mem_cache *c = container_of(head, struct bpf_mem_cache, rcu);
-	struct llist_node *llnode = llist_del_all(&c->waiting_for_gp);
 	struct llist_node *pos, *t;
 
 	llist_for_each_safe(pos, t, llnode)
-		free_one(c, pos);
+		free_one(pos, percpu);
+}
+
+static void __free_rcu(struct rcu_head *head)
+{
+	struct bpf_mem_cache *c = container_of(head, struct bpf_mem_cache, rcu);
+
+	free_llist(llist_del_all(&c->waiting_for_gp), !!c->percpu_size);
 	atomic_set(&c->call_rcu_in_progress, 0);
 }
 
@@ -441,7 +446,7 @@ int bpf_mem_alloc_init(struct bpf_mem_alloc *ma, int size, bool percpu,
 
 static void drain_mem_cache(struct bpf_mem_cache *c)
 {
-	struct llist_node *llnode, *t;
+	bool percpu = !!c->percpu_size;
 
 	/* No progs are using this bpf_mem_cache, but htab_map_free() called
 	 * bpf_mem_cache_free() for all remaining elements and they can be in
@@ -450,14 +455,10 @@ static void drain_mem_cache(struct bpf_mem_cache *c)
 	 * Except for waiting_for_gp list, there are no concurrent operations
 	 * on these lists, so it is safe to use __llist_del_all().
 	 */
-	llist_for_each_safe(llnode, t, __llist_del_all(&c->free_by_rcu))
-		free_one(c, llnode);
-	llist_for_each_safe(llnode, t, llist_del_all(&c->waiting_for_gp))
-		free_one(c, llnode);
-	llist_for_each_safe(llnode, t, __llist_del_all(&c->free_llist))
-		free_one(c, llnode);
-	llist_for_each_safe(llnode, t, __llist_del_all(&c->free_llist_extra))
-		free_one(c, llnode);
+	free_llist(__llist_del_all(&c->free_by_rcu), percpu);
+	free_llist(llist_del_all(&c->waiting_for_gp), percpu);
+	free_llist(__llist_del_all(&c->free_llist), percpu);
+	free_llist(__llist_del_all(&c->free_llist_extra), percpu);
 }
 
 static void free_mem_alloc_no_barrier(struct bpf_mem_alloc *ma)
-- 
2.29.2