3 files changed, 25 insertions, 4 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 8821b9a..5f520f5 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -123,7 +123,10 @@ struct bpf_prog_aux {
 	const struct bpf_verifier_ops *ops;
 	struct bpf_map **used_maps;
 	struct bpf_prog *prog;
-	struct work_struct work;
+	union {
+		struct work_struct work;
+		struct rcu_head	rcu;
+	};
 };
 
 struct bpf_array {
@@ -153,6 +156,7 @@ void bpf_register_map_type(struct bpf_map_type_list *tl);
 
 struct bpf_prog *bpf_prog_get(u32 ufd);
 void bpf_prog_put(struct bpf_prog *prog);
+void bpf_prog_put_rcu(struct bpf_prog *prog);
 
 struct bpf_map *bpf_map_get(struct fd f);
 void bpf_map_put(struct bpf_map *map);
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 614bcd4..cb31229 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -202,7 +202,7 @@ static int prog_array_map_update_elem(struct bpf_map *map, void *key,
 
 	old_prog = xchg(array->prog + index, prog);
 	if (old_prog)
-		bpf_prog_put(old_prog);
+		bpf_prog_put_rcu(old_prog);
 
 	return 0;
 }
@@ -218,7 +218,7 @@ static int prog_array_map_delete_elem(struct bpf_map *map, void *key)
 
 	old_prog = xchg(array->prog + index, NULL);
 	if (old_prog) {
-		bpf_prog_put(old_prog);
+		bpf_prog_put_rcu(old_prog);
 		return 0;
 	} else {
 		return -ENOENT;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 98a69bd..a1b14d1 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -432,6 +432,23 @@ static void free_used_maps(struct bpf_prog_aux *aux)
 	kfree(aux->used_maps);
 }
 
+static void __prog_put_rcu(struct rcu_head *rcu)
+{
+	struct bpf_prog_aux *aux = container_of(rcu, struct bpf_prog_aux, rcu);
+
+	free_used_maps(aux);
+	bpf_prog_free(aux->prog);
+}
+
+/* version of bpf_prog_put() that is called after a grace period */
+void bpf_prog_put_rcu(struct bpf_prog *prog)
+{
+	if (atomic_dec_and_test(&prog->aux->refcnt)) {
+		prog->aux->prog = prog;
+		call_rcu(&prog->aux->rcu, __prog_put_rcu);
+	}
+}
+
 void bpf_prog_put(struct bpf_prog *prog)
 {
 	if (atomic_dec_and_test(&prog->aux->refcnt)) {
@@ -445,7 +462,7 @@ static int bpf_prog_release(struct inode *inode, struct file *filp)
 {
 	struct bpf_prog *prog = filp->private_data;
 
-	bpf_prog_put(prog);
+	bpf_prog_put_rcu(prog);
 	return 0;
 }