bpf: Call maybe_wait_bpf_programs() only once from generic_map_delete_batch()

As stated in the comment found in maybe_wait_bpf_programs(),
the synchronize_rcu() barrier is only needed before returning
to userspace, not after each deletion in the batch.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20220218181801.2971275-1-eric.dumazet@gmail.com

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index a72f63d..9c7a72b 100644 (file)
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1352,7 +1352,6 @@ int generic_map_delete_batch(struct bpf_map *map,
                err = map->ops->map_delete_elem(map, key);
                rcu_read_unlock();
                bpf_enable_instrumentation();
-               maybe_wait_bpf_programs(map);
                if (err)
                        break;
                cond_resched();
@@ -1361,6 +1360,8 @@ int generic_map_delete_batch(struct bpf_map *map,
                err = -EFAULT;
 
        kvfree(key);
+
+       maybe_wait_bpf_programs(map);
        return err;
 }