Re: [PATCH net-next 3/4] ynl: replace print with NlError

[Jakub Kicinski <kuba@kernel.org>]

On Fri, 17 Mar 2023 17:23:39 -0700 Stanislav Fomichev wrote:
> Instead of dumping the error on the stdout, make the callee and
> opportunity to decide what to do with it. This is mostly for the
> ethtool testing.

> diff --git a/tools/net/ynl/lib/ynl.py b/tools/net/ynl/lib/ynl.py
> index 21c015911803..6c1a59cef957 100644
> --- a/tools/net/ynl/lib/ynl.py
> +++ b/tools/net/ynl/lib/ynl.py
> @@ -67,6 +67,13 @@ from .nlspec import SpecFamily
>      NLMSGERR_ATTR_MISS_NEST = 6
>  
>  
> +class NlError(Exception):
> +  def __init__(self, nl_msg):
> +    self.nl_msg = nl_msg
> +
> +  def __str__(self):

Why not __repr__ ?

> +    return f"Netlink error: {os.strerror(-self.nl_msg.error)}\n{self.nl_msg}"
> +

nit: double new line here

>  class NlAttr:
>      def __init__(self, raw, offset):
>          self._len, self._type = struct.unpack("HH", raw[offset:offset + 4])
> @@ -495,9 +502,7 @@ genl_family_name_to_id = None
>                      self._decode_extack(msg, op.attr_set, nl_msg.extack)
>  
>                  if nl_msg.error:
> -                    print("Netlink error:", os.strerror(-nl_msg.error))
> -                    print(nl_msg)
> -                    return
> +                    raise NlError(nl_msg)
>                  if nl_msg.done:
>                      if nl_msg.extack:
>                          print("Netlink warning:")