bpf: Use rcu_read_lock_dont_migrate in bpf_sk_storage.c

Use rcu_read_lock_dont_migrate() and rcu_read_unlock_migrate() in
bpf_sk_storage.c to obtain better performance when PREEMPT_RCU is
not enabled.

Signed-off-by: Fushuai Wang <[email protected]>
Signed-off-by: Martin KaFai Lau <[email protected]>
Link: https://patch.msgid.link/[email protected]

Author: Fushuai Wang

net/core/bpf_sk_storage.c

@@ -50,16 +50,14 @@ void bpf_sk_storage_free(struct sock *sk)
 {
 	struct bpf_local_storage *sk_storage;
 
-	migrate_disable();
-	rcu_read_lock();
+	rcu_read_lock_dont_migrate();
 	sk_storage = rcu_dereference(sk->sk_bpf_storage);
 	if (!sk_storage)
 		goto out;
 
 	bpf_local_storage_destroy(sk_storage);
 out:
-	rcu_read_unlock();
-	migrate_enable();
+	rcu_read_unlock_migrate();
 }
 
 static void bpf_sk_storage_map_free(struct bpf_map *map)
@@ -161,8 +159,7 @@ int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk)
 
 	RCU_INIT_POINTER(newsk->sk_bpf_storage, NULL);
 
-	migrate_disable();
-	rcu_read_lock();
+	rcu_read_lock_dont_migrate();
 	sk_storage = rcu_dereference(sk->sk_bpf_storage);
 
 	if (!sk_storage || hlist_empty(&sk_storage->list))
@@ -213,8 +210,7 @@ int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk)
 	}
 
 out:
-	rcu_read_unlock();
-	migrate_enable();
+	rcu_read_unlock_migrate();
 
 	/* In case of an error, don't free anything explicitly here, the
 	 * caller is responsible to call bpf_sk_storage_free.