Re: [Patch, v2, 1/2] BCC: Python: Support 'fmod_ret' method for eBPF

[Matthieu Baerts <matttbe@kernel.org>]

Hi Gang,

On 09/04/2025 09:17, Gang Yan wrote:
> In kernel, there exists a lot of 'fmod_ret' functions, such as
> 'update_socket_protocol'. But it cannot attached in BCC-python directly,
> so this patch provides an interface for python to use 'fmod_ret'
> attaching method.
> 
> But there exists a question about how to check 'fmod_ret' support in
> kernel, do you have any suggestion? I already considered checking the
> kernel version which seems not suitable.
> 
> Signed-off-by: Gang Yan <yangang@kylinos.cn>
> ---
>  src/python/bcc/__init__.py | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/src/python/bcc/__init__.py b/src/python/bcc/__init__.py
> index 8bc85516..12ce3ef6 100644
> --- a/src/python/bcc/__init__.py
> +++ b/src/python/bcc/__init__.py

(...)

> @@ -1189,6 +1205,22 @@ class BPF(object):
>          self.kfunc_entry_fds[fn_name] = fd
>          return self
>  
> +    def attach_fmod_ret(self, fn_name=b""):
> +        fn_name = _assert_is_bytes(fn_name)
> +        fn_name = BPF.add_prefix(b"kmod_ret__", fn_name)
> +
> +        if fn_name in self.fmod_ret_fds:
> +            raise Exception("Fmod_ret func %s has been attached" % fn_name)
Detail: maybe clearer with this:

  "Fmod_ret func %s is already attached"

(...)

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.